####018010252#### FXUS62 KCHS 160820 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 420 AM EDT Fri May 16 2025 .SYNOPSIS... Broad high pressure will remain across the area through the remainder of the week. A weak cold front may push over the region early next week, remaining generally stationary through Tuesday. A stronger cold front is timed to sweep across the region Wednesday into Wednesday night. && .NEAR TERM /THROUGH TONIGHT/... Today: On water vapor this morning a vertically stacked low pressure was noted across the eastern Dakotas. Over the southeastern United States this has allowed for mid-level heights to rise with a ridge axis extending through eastern Georgia and South Carolina. 1000/ 850 mb thicknesses have responded to this with values now forecast to approach 1425- 1430 m during peak heating. 850 mb temperatures are also forecast to be around 18/ 19 degrees C. Both of the values above would support high temperatures in the upper 90s. However, given the wet ground from recent precipitation and periodic high clouds (which should hold back high temperatures a degree or two) high temperatures will likely range in the 94 to 97 F range. A sea breeze will also take shape this afternoon and begin to push inland late afternoon. The records at Charleston and Savannah Intl Airports today will likely be challenged, while the Downtown Charleston/ Waterfront Park record will be safe due to development of the sea breeze. More information can be found in the climate section below. No precipitation is expected today given capping around 750 mb and a relatively dry PBL. In fact, even the Cu field looks rather paltry for today. Heat index values are forecast to be in the 98 to 104 F range as dewpoints will likely mix out some this afternoon. The experimental Heat Risk level remains in the level 2/ moderate risk category (orange) which indicates that this level of heat will affect most individuals who are sensitive to heat. Tonight: No precipitation is expected as mid-level ridging persists. Expect low temperatures in the upper 60s to lower 70s. && .SHORT TERM /SATURDAY THROUGH MONDAY/... Saturday: The vertically stacked low that was over the Dakotas on Friday will move east and cross the Great Lakes region early Saturday morning with widespread convection over the Ohio River Valley diving southeast. Convection will likely reach the Appalachians by late Friday evening/ early Saturday morning. Even though mid-level ridging is forecast to weaken Saturday, capping looks rather potent Saturday morning. As such, high res guidance is rapidly decaying the MCS to where nothing is left across the Midlands and Lowcountry of South Carolina. Given the capping and the forecast displacement of the MCS from the parent upper level forcing, this makes sense. The GFS deterministic and some of its ensemble members still show some hints of convection on Saturday, but the EPS and GEPS are rather dry. Thicknesses on Saturday do fall to around 1420 - 1425 m so high temperatures will likely be in the lower to mid 90s. Low temperatures will again be in the upper 60s to lower 70s (mid 70s at area beaches). Sunday: Short term guidance indicates that a wavy stationary front will linger over the forecast area during the daylight hours Sunday. NAM and ECMWF indicate that a MCS sourced from the Mid-Mississippi River Valley will track along the stationary front, passing just south of the Appalachians, reaching SE GA/SC during the afternoon hours. Although this scenario is possible, it would be largely dependent on the placement of the stationary front, which remain uncertain. However, the GFS shows a more plausible setup for afternoon convection. The GFS indicates that a mid-level disturbance, possibly an MCV, rippling over the forecast area during the afternoon. The passage of the disturbance may coincide with a sea breeze Sunday afternoon. Given afternoon temperatures in the low to mid 90s over dewpoints around 70 degrees may yield a field of 1000-1500 J/kg with little to no CIN. This setup should result in at least isolated to scattered showers and thunderstorms. Coverage could be greater near the intersection of the sea breeze and stationary front. Convection should track off the coast or dissipate around sunset Sunday evening. Sunday night, low temperatures are forecast to range from the upper 60s inland to the low 70s along the coast. Patchy fog is possible over areas of rainfall from the Sunday afternoon storms. Due to high uncertainty, the forecast will not indicate fog at this time. Monday: H5 ridge centered over the Gulf will build across the Deep South through the day, with heights gradually increasing from the west. Given partly sunny conditions and increasing llvl thicknesses, temperatures are forecast to peak in the low to mid 90s. As temperatures warm, a sea breeze should advance inland through the afternoon hours. Slight steeper lapse rates over the SC Lowcountry should support at least isolated showers and thunderstorms along and ahead of the sea breeze. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... The axis of H5 ridge centered over the Gulf should ripple over the forecast area by Tuesday. Temperatures should begin the day around 70 degrees, then warming quickly through mid-day. High temperatures are forecast to range in the mid 90s, with upper 90s possible across extreme SE GA. It possible that record temperatures could be challenged, see climate section below. Given the ridge aloft, the environment across the forecast should remain capped. Hot and dry conditions expected for Tuesday. Tuesday night, temperatures will remain mild, with lows around 70 degrees. Wednesday: Guidance indicates a strong area of low pressure deepening across the Ohio River Valley through the day. The associated cold front should sweep quickly east, timed to push across the forecast area during the heat of the afternoon. Forecast soundings indicate strong llvl wind fields, with 6 km shear exceeding 50 kts during the afternoon. Afternoon temperatures around 90 degrees and dewpoints around 70 degrees is forecast to yield CAPE between 1000-1500 kts. Interestingly, the forecast soundings indicate mixing above 5 kft, supporting afternoon gusts around 25 mph. In addition, the inverted V sounding may yield DCAPE values around 1000 J/kg. Given the favorable timing of the cold front and forecast environment, severe thunderstorms are possible on Wednesday, with damaging wind gusts the primary hazard. Thursday into Friday, closed mid-level low will track over the NE CONUS, with the trough axis swinging over the forecast area Thursday into Thursday night. In the wake of the cold front, cooler thicknesses will build across the region on Thursday, lingering into Friday. Conditions will remain generally dry with temperatures returning to around normal. Thursday highs should range in the low to mid 80s, with Friday highs around 80 across the SC Lowcountry to mid 80s across SE GA. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... Today/ Friday: VFR/ no precipitation forecast. Light southwest winds through the early morning hours then slowly veering from the west after daybreak. By the afternoon, a sea breeze will begin to form along the SC/ GA coast and start to move inland. Winds at KJZI will back from the south/ southwest first followed by KCHS and KSAV. Tonight: VFR. Extended Aviation Outlook: Generally VFR. The risk for showers/tstms Sunday afternoon. && .MARINE... Today: High pressure located across south/ central Florida will favor southwest flow over the waters with winds 10 to 15 kt. During the afternoon, winds will back from the south and increase in speed as a sea breeze circulation becomes established. Winds will gust up to 20 kt at times, but remain below advisory criteria. Seas 2-4 ft. Tonight: A sea breeze will be moving inland with southerly winds over the waters beginning to veer from the southwest as the circulation begins to lose cohesion. Seas 2-4 ft. Saturday: A weak cold front will remain just north of the waters on Saturday, but still be close enough to allow wind gusts to approach 25 kt. For now, no Small Craft Advisory is anticipated for Saturday. Sunday through Wednesday: For the period between Sunday through Tuesday, the marine zones will remain between high pressure centered over the western Atlantic and Low pressure tracking across the middle of the US. This pattern should support south winds around 10 kts with seas around 2 ft. On Wednesday, a strong cold front will approach from the west during the morning, reaching the marine waters by the afternoon. A squall line of thunderstorms may develop along and ahead of the front, pushing across waters during the afternoon. It possible these storms will produce gusts in excess of 34 kts. In addition, a steep pressure gradient should support southwest winds between 15 to 20 kts with gusts around 25 kts. Seas should build to 3-4 ft. Small Craft Advisories could be posted to highlight the wind conditions on Wednesday. && .CLIMATE... Record High Temperatures: May 16: KCHS: 94/1941 KSAV: 95/1915 May 19: KSAV: 97/1996 May 20: KSAV: 96/2006 Record High Minimum Temperatures: May 16: KCHS: 71/2018 KSAV: 74/1915 May 17: KCHS: 74/1995 KCXM: 75/1998 KSAV: 74/1995 May 18: KCHS: 75/1995 KCXM: 77/1991 KSAV: 74/1899 May 19: KSAV: 74/1930 May 20: KCHS: 72/2022 KCXM: 76/2022 KSAV: 73/1896 May 21: KCHS: 74/2022 KSAV: 74/2017 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...Haines SHORT TERM...Haines/NED LONG TERM...NED AVIATION...Haines/NED MARINE...Haines/NED ####018012184#### FXUS61 KBOX 160821 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 421 AM EDT Fri May 16 2025 .SYNOPSIS... Weakening low pressure will bring scattered showers or thunderstorms at times through the end of the week as it reaches New England, but a majority of the time will be dry. A cold front moves through Saturday night behind the storms, drying and cooling the region. Even with mostly dry conditions, scattered showers remain possible Sunday with a cold pool aloft, then the pattern turns unsettled again toward midweek. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Key Messages: * Fog and stratus disperses around mid to late morning, but lingers over the Cape and Islands most of the day. * Scattered t-storms possible late in the day (after 3 PM) in western New England, but severe weather is not expected. Details: Mild and moist early-morning across Southern New England, with an extensive field of stratus blanketing a large portion of the Northeast. Fog has developed in most locations as well, but so far visibilities have been lowest along the coast, at times as low as one-quarter mile but they've generally been at or around half a mile. Coordinated with NWS New York City on special weather statement for fog through 13z along the South Coast/South Shore, Cape and Islands. Otherwise temps were in the low 60s with similar dewpoints. On the larger scale, we're in a period of midlevel subsidence/weak geopotential height rises, though that stands to change later this afternoon as we start to feel increasing height falls associated with a seasonably strong upper low over the Gt Lakes region. Probably won't see substantial improvement/scattering of fog and stratus until mid-morning at earliest in western and northern MA into CT, and around late morning to noontime for the Boston to Providence corridor. Given the marine boundary layer, stratus may linger for much of the day along the South Coast, Cape and Islands. Should be generally dry for most given the subsidence aloft; however some threat for scattered showers and thunderstorms still looks to materialize late in the day (probably not earlier than 3 PM and tending to down-trend by sundown) and mainly west of Fitchburg to Worcester to Willimantic with the onset of geopotential height falls. In what still is best characterized as a weakly-forced setup, the suite of convective-permitting guidance has been all over the place as far as placement goes, but looks like the greatest coverage of storms will be more to our north and west, and we'll have to watch to see if storms can make it over the Berkshires/southern VT. Some instability (around 1000-1200 J/kg) from diurnal heating should be present in western portions of the CWA, but low to midlevel flow is pretty weak and that limits shear magnitudes to less than 30 kt. Given this, probably not seeing much in the way of severe weather potential with this activity but lightning and brief downpours are still threats. Since this activity would stem from last night's round of severe weather in the Gt Lakes region, any smaller- scale impulse from that activity could modify that thinking, and that's something to watch as we move through today, but currently don't see indication of that in obs upstream. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... Key Messages: * Fog and stratus develop again tonight, and it may linger for quite a while into Saturday. * Possible round of scattered t-storms Saturday morning in most areas. * Better chance at t-storms between 2-8 PM west of Worcester. Some could become strong. Details: Tonight and Saturday: Any showers or storms in western New England should weaken/dissipate early tonight. We will end up seeing stratus and fog return northward from the waters again tonight. What will also be taking place in mid and upper levels late tonight and into Saturday is the potent upper low over the Great Lakes will continue to make eastward progress into the eastern part of Michigan. This will induce greater height falls and diffluent flow aloft to overspread much of the Northeast. Given the moist airmass in place, it won't take much heating or much of a shortwave triggering mechanism at all to get showers and t-storms going. What is also unclear is how today's severe weather setup in the Ohio Valley may influence shower/t-storm coverage or development. There are unfortunately quite a bit of uncertainties as it pertains to thunderstorm potential as we move into Saturday, which is problematic given the number of outdoor events happening, and makes it a difficult call as far as timing and strength of storms goes. The potential exists for a couple rounds of storms, possibly as early as the pre- dawn/early-morning Saturday period in some model solutions; and although this would not likely become strong, it could still be capable of some lightning. There is some loose consensus on a second round of scattered storms during the midafternoon to early evening hours, and it's this second round that may have the better potential for severe weather mainly for interior Southern New England near/west of Worcester. With this second round, low and midlevel flow increases to the point where forecast hodographs become pretty curved in a low-LCL setting, As indicated in the machine-learning progs, potential for locally strong winds and/or a tornado could develop in western MA/CT if storms can root themselves at the surface. That leads to the next source of uncertainty, in that we may still be dealing with quite a bit of stratus and low clouds from the overnight lingering even into the afternoon. The longer those low clouds stick around, the less likely we'll destabilize enough. Took the approach of keeping thunder probs low in the morning hours, with an isolated mention of thunderstorms. Although I still carry an isolated thunder mention in eastern MA and RI, I opted to instead increase probs for thunder in western MA and CT with the second round of possible storms. Felt uncertainties that I described were too much to include any enhanced wording but that might need to be considered later. Those with outdoor plans on Saturday will want to keep a close eye to the forecast and monitor for changes. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Key Messages: * Cold front moves through Saturday night, drying and cooling the region * Unsettled weather makes a return later in the week Details... Any lingering showers or storms will clear out Saturday night as a cold front passes through southern New England. Generally, the timing for the end of these storms is still somewhat uncertain. Some CAMs are hinting at a line moving through the region after 8 PM, which will be something to monitor. This would depend on how much energy and general instability is left following what moves through in the afternoon/evening, though. Behind the front, drier and cooler conditions with a cold pool settling in aloft that will likely continue into the start of next week. Some scattered showers do remain possible through Sunday as the mid-level low continues its exit offshore into the Gulf of Maine and the cold pool lingers. High temperatures will likely remain in the 60s and low 70s in some spots with less cloud cover Monday, then as the cold pool lingers highs through midweek will likely remain in the 60s. Some brief mid-level ridging will shift towards southern New England with surface high pressure to start the work week, but the pattern turns unsettled once again towards midweek as another mid-level low over the Great Lakes strengthens and an associated surface low shifts to the northeast from the Ohio River Valley. Some guidance indicates a surface low splitting off from this one in the OH River Valley and moving along the east coast, which could end up impacting southern New England in the form of increased cloud cover and rain chances. However, it is still quite far out in time for any finer details. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 06z TAF Update: Through 12z Friday: High confidence overall, but lower to moderate on areal extent of fog. IFR-LIFR in at least stratus, although areas VLIFR visby in dense fog mainly along south-coastal/Cape airports. Visbys could stay around MVFR-IFR range in BR away from the waters. Light S winds. Today: Moderate confidence. IFR-LIFR stratus/fog scatters to MVFR-VFR range 13-15z, although IFR likely to continue most of if not all day along the South Coast, Cape Cod airports. Isolated to widely SCT SHRA/TS mainly near and northwest of a BDL-ORH line, timing uncertain but thinking no sooner than 17z, activity ending closer to or just after sundown. Light S winds, with potential for seabreeze at BOS as low ceilings scatter out around 15-17z. Tonight: Moderate confidence. IFR-LIFR ceilings and visbys return from the coastal waters. Should be mostly dry, but lower prob of SHRA/TS after 09z over southwestern areas. Saturday: Moderate confidence overall, but low on timing both sub-VFR improvement and on timing SHRA/TS. IFR-LIFR stratus likely to begin Sat, but it is uncertain if and when we see any improvement. Leaned toward MVFR-VFR by late morning but that could be optimistic, especially east of ORH. Couple rounds of TS possible, potentially as early as 12-13z and with another round that would mostly be focused for western airports after 17z. Some storms could become strong, with a better chance for strong activity in the 2nd round of storms for BAF- BDL- ORH. Winds mainly SE to S around 5-10 kt. KBOS TAF...Moderate confidence. IFR ceilings could trend LIFR as we move toward daybreak, then scattering out around 14-15z to MVFR-VFR categories. Seabreeze possible as soon as 15z once stratus disperses, which would continue til 23z. KBDL TAF...Moderate confidence. MVFR-IFR should disperse to VFR bases around 14z. PROB30 for ISO/SCT TS after 17z, the TS risk ending around 00z. Outlook /Saturday Night through Tuesday/... Saturday Night: VFR. Chance SHRA. Sunday through Sunday Night: Mainly VFR, with local MVFR possible. Breezy. Slight chance SHRA. Monday through Tuesday: VFR. Breezy. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. High confidence overall. Expect sub-SCA conditions to prevail on the waters. Fog and reduced visibility will be the biggest potential hazard for mariners today and tonight, with S winds around 10 kt and seas 4 ft or less. Risk for thunderstorms could develop as soon as pre-dawn Saturday over the southern waters, with another round of storms possible into Saturday afternoon. Outlook /Saturday Night through Tuesday/... Saturday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, isolated thunderstorms. Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Monday: Winds less than 25 kt. Areas of seas approaching 5 ft. Monday Night through Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...Loconto/Hrencecin NEAR TERM...Loconto SHORT TERM...Loconto LONG TERM...Hrencecin AVIATION...Loconto/Hrencecin MARINE...Loconto/Hrencecin ####018011810#### FXUS61 KPHI 160822 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 422 AM EDT Fri May 16 2025 .SYNOPSIS... A warm front lifts north across the area this morning. Periods of showers, thunderstorms, and humidity continue through Saturday ahead of a strong cold front that passes through late Saturday afternoon into Saturday evening. High pressure builds into the area on Sunday and persists into Tuesday before another period of unsettled weather returns Wednesday into Thursday. && .NEAR TERM /THROUGH TONIGHT/... 315 AM...It's relatively quiet across the area at the moment as weak ridging is briefly moving through. The main concern is areas of dense fog and so as a result, much of the area is under a Dense Fog Advisory through this morning. Otherwise, our attention turns to an MCS located upstream to our west. At this time it has started to weaken some as it moves across southern Ontario and Lake Erie though it's still producing quite a bit of lightning. This MCS is located near the triple point associated with a large and deep area of low pressure centered near Minnesota. As we get into the day Friday, our attention will turn to the MCS as it will be continuing to weaken but is likely to move into the area from west to east sometime beginning around the mid to late morning over our western most counties in eastern PA and reaching the I-95 corridor shortly there after as it should continue to be pretty quick moving. There remains some uncertainty regarding how strong it will be at this time as it moves into our area. But given that ML CAPE values will be increasing to 1000+ j/kg with bulk shear values around 35 to 40 knots certainly the potential is still there for severe weather. As a result, there has been little change to the outlook from the Storm Prediction Center as areas basically from near Allentown PA to Trenton NJ south and southwestward remain in a SLIGHT risk for severe weather with a MARGINAL risk to the north. Damaging winds and large hail look to be the biggest threats but a brief tornado or two cannot be ruled out. Finally, given how wet it's been and that these storms will be capable of producing very heavy downpours, localized flooding will also be possible. As we get further into the day Friday towards the afternoon and early evening, the forecast becomes a little more uncertain. Following the initial round of showers/storms with the MCS there are indications that more scattered convection develops as we go through the afternoon. This later convective development could on the one hand be aided by residual boundaries from the earlier convection but could also be mitigated if the MCS takes longer to move through since this would give the atmosphere less time to recover. Otherwise, the morning fog will have been broken up with the first round of convection moving through and we may even see some sunny breaks or partial sunshine for a time in the afternoon. But again, this could fuel convective redevelopment and this second round of storms could also be severe. It will be a warm and very humid day with highs generally ranging from the mid to upper 70s north to the low to mid 80s south. Right near the shore though it will be a bit cooler. For Friday night, there may still be some convection ongoing into the evening but this should diminish with time leading to another brief lull. Once again, there could be some low clouds, mist, and fog that form due to the continuing moist environment. The action won't be over though because by later Friday night the main slug of energy more directly associated with low will be approaching and this could bring another MCS into the area sometime either overnight Friday night or Saturday morning. There remains a lot of uncertainty on this though. Otherwise, it will be a mild, muggy night with lows mainly in the 60s. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... Mid/upper level low over the Great Lakes will pivot east on Saturday as a vigorous shortwave tracks across the Mid-Atlantic with northwest flow developing in its wake on Sunday. At the surface, an area of low pressure will slide across Ontario/Quebec by Saturday night before meandering near Nova Scotia on Sunday. A strong cold front will pass through the area late Saturday afternoon into Saturday night. To start out Saturday, a MCS originating from the lower Ohio Valley is progged to approach our area on Saturday morning. The overall nature of this feature depicted by the latest CAM guidance is that it will be decaying or even dissipate as it approaches our area. A few showers and thunderstorms may be possible through the morning hours especially north and west, but since this feature is mesoscale driven, it's very difficult to depict where this feature may be come Saturday morning. Skies should be partly to mostly cloudy through the morning however, before clearing out by early afternoon. Temperatures will climb into the 80s for most areas with dew points in the low to mid 60s making it feel quite uncomfortable outside. The cold front will continue to make its way east through the afternoon where isolated to scattered thunderstorms will re-develop by the afternoon. In addition to the better forcing, we'll have MLCAPE values around 1000-1500 J/kg, DCAPE around 900 J/kg, and modest shear as indicated by point forecast soundings. These parameters will support damaging winds being the primary concern and possibly some severe hail. A brief tornado also cannot be ruled out as some low level shear will be in place. This is in line with the Storm Prediction Center which keeps the entire area in a Slight Risk (Level 2/5). Unfortunately, this threat is conditional and entirely dependent on the morning MCS and how it evolves, so the forecast may vary significantly by this time tomorrow. Nonetheless, the cold front will push off the coast by Saturday night and the threat for storms wanes in addition to the loss of daytime heating. Sunday is looking like the better half of the weekend as tranquil weather returns with the upper trough moving further east. Partly to mostly cloudy skies are expected with dry conditions and lower humidity. Perhaps an isolated shower is possible north and west, but general thinking is most of the area will stay dry. The one thing to note is winds will increase as diurnal mixing occurs as the area lies wedged between systems resulting in a tightening pressure gradient. Wind gusts up 30-35 mph will be possible. Gusts will diminish into Sunday night under mostly clear skies. Despite the windy conditions, high temperatures should mainly be in the 70s (with 60s in the Poconos). && .LONG TERM /MONDAY THROUGH THURSDAY/... By Monday, low pressure over the Canadian Maritimes will begin to move further east into the North Atlantic. At the same time, high pressure will settle over the Mid-Atlantic before moving offshore on Tuesday. Aloft, the area will be situated under northwest flow in wake of exiting upper trough. All in all, a tranquil weather period is in store with mostly clear skies, light winds and dry weather. By Tuesday night and through the middle of the week, our attention will turn to our next weather system which will take aim at the area. Global and ensemble guidance both feature a deep upper trough moving into the Great Lakes/Northeast region around the middle of the week with a potential coastal low developing before moving up towards New England. This would indicate another period of unsettled weather with periods of rain starting as early as Tuesday night, and more so on Wednesday and Thursday. Still quite a ways out from this potential, so have generally stuck with NBM guidance and capped rain chances at chance (~30-50%). In terms of temperatures, we'll encounter temperatures around average on Monday, before dipping below average for Tuesday through Thursday as the area remains situated within the deep upper trough. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Rest of overnight...Generally IFR to LIFR due to low clouds and fog. Winds light and variable to calm. Friday...Restrictions likely to start, then some improvement to MVFR expected between 15-18Z. However, around this time there will be a complex of showers and storms moving through as it moves in from the west but still some uncertainty on the details including how strong it will be at this time. Winds light and variable early in the day becoming SW 5 to 10 knots in the afternoon. There could be some additional showers/storms that form in the mid to late afternoon. Moderate confidence. Friday night...Any showers/storms diminish through the evening with with the potential for low cigs and low visbys once again due to stratus, mist and fog. Low MVFR or IFR appears likely. More showers and storms could move in late. S to SW winds around 5 knots. Low confidence. Outlook... Saturday through Saturday night...Primarily VFR expected. Scattered showers and thunderstorms likely, especially during the afternoon and early evening. Any shower or thunderstorm may cause temporary sub-VFR conditions, gusty winds and/or visibility restrictions. Sunday through Tuesday...VFR. Gusty winds up to 25-30 kt possible on Sunday. Otherwise, no significant weather expected. && .MARINE... Areas of dense fog over the waters likely to be an issue through the first half of Friday. Beyond this time, increasing chances for showers/storms over the waters in the afternoon. Generally sub SCA except any storms could produce locally strong winds. The risk for some showers/storms over the waters continues Friday night along with the potential for low visbys due to fog. Outlook... Saturday through Saturday night...No marine headlines expected. Sunday through Sunday night...SCA conditions possible due to wind gusts up to 25 kt. Monday through Tuesday...No marine headlines expected. && .TIDES/COASTAL FLOODING... The Coastal Flood Advisory for northwestern Burlington and lower Bucks Counties has been extended until 8 AM Saturday. Minor coastal flooding is expected with the early morning high tide this morning and on Saturday. It's possible minor coastal flooding may occur on Sunday as well, where further extensions may be needed. For areas of the lower tidal Delaware River near Philadelphia may encounter spotty minor coastal flooding through Saturday, but should fall short of advisory levels. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Dense Fog Advisory until 11 AM EDT this morning for PAZ054-055- 060>062-070-071-101>106. Coastal Flood Advisory until 8 AM EDT Saturday for PAZ106. NJ...Dense Fog Advisory until 11 AM EDT this morning for NJZ001- 007>010-012>027. Coastal Flood Advisory until 8 AM EDT Saturday for NJZ019. DE...Dense Fog Advisory until 11 AM EDT this morning for DEZ001>004. MD...None. MARINE...Dense Fog Advisory until noon EDT today for ANZ430-431-450>455. && $$ SYNOPSIS...DeSilva/Hoeflich NEAR TERM...Fitzsimmons SHORT TERM...DeSilva LONG TERM...DeSilva AVIATION...DeSilva/Fitzsimmons MARINE...DeSilva/Fitzsimmons TIDES/COASTAL FLOODING...PHI ####018011537#### FXUS63 KEAX 160823 AFDEAX Area Forecast Discussion National Weather Service Kansas City/Pleasant Hill MO 323 AM CDT Fri May 16 2025 .KEY MESSAGES... - Isolated/Scattered Shower Activity Friday; Robust Activity Far Eastern Missouri and Far Southeast Missouri - Mild Weather Conditions Saturday - Active Pattern Starts Sunday, Continues Through Wednesday - Severe Storms Favorable Monday and Tuesday; Heavy Rain Could Lead to Flooding && .DISCUSSION... Issued at 321 AM CDT Fri May 16 2025 Multiple features at the surface and in mid/upper-levels present across the Central CONUS setting up differing areas active weather and areas of more mild weather conditions. The most prominent feature is a closed-low through 300mb currently centered over the far eastern portions of the Northern Plains as of 0700 UTC this morning. This is creating southwesterly flow across the bulk of the Central CONUS to near the mid-Atlantic Region. A secondary though strong short-wave trough is working through this southerly flow, with strong vort maxima and 120kt H5 jet streak working through Kansas early this morning, with then another H5 jetstreak around 100kt in magnitude heading toward the Ozarks Region. The primary surface cyclone has become vertically stacked over the eastern portions of the Northern Plains. Short-wave trough over Kansas though is promoting stronger dCVA resulting in localized surface pressure falls across the Central Plains, and objective surface map analysis indicating this is forming a compact surface cyclone. The cold front that was associated with main surface cyclone has cleared through the Ozarks Region this morning and is headed toward the Tennessee Valley. However from Central Kansas into the lower Missouri River Valley, surface winds have turned southwesterly in response to the secondary surface cyclone developing underneath the mid-level vort maxima where ascent has been ongoing. Therefore, this has been maintaining WAA during the overnight hours despite the previous frontal passage. We have really only seen a notable drop in dewpoints, but not air temps. As this H5 jet streak works toward the east-northeast through the morning and afternoon, there is some potential for isolated to scattered sprinkles. 00z and 06z CAM simulated reflectivity fields have shown weak development from northeast Kansas into northwest Missouri between 11z-15z this morning. Western and north-central Kansas radars have shown some returns during the overnight hours but no surface stations reported anything reaching the ground. Will place isolated to scattered sprinkles in the forecast as this forcing moves through. There will be some moisture transport as this feature moves through, but with flow more southwesterly than southerly, will not be overly robust. Therefore, should see breaks in any cloud cover that helps temperatures reach back into the lower 80s, some areas perhaps only upper 70s. If the ascent in the dCVA region continues, secondary surface cyclone deepening will result in a stronger pressure gradient increasing southwesterly winds. Current model soundings do show deeper mixing occurring in areas with clearing today, with winds around 30 kts toward the top of the mixed layer. Therefore, expecting wind gusts 25-35 MPH this afternoon. Far northwestern Missouri may reach above 40 MPH for an hour or two. For now, not seeing a strong enough signal to hoist a wind advisory in northwest Missouri, but will continue to monitor conditions. If elevated showers develop, may see those transport greater momentum toward the surface. Eventually the H5 streak moves into the upper Mississippi River Valley and pulls the remainder of the surface cyclone through by late afternoon, while the closed-cyclone in the upper-midwest provides northwesterly flow and pushes another cool front across the area. Stronger moisture transport from the Ozarks into the western Ohio River Valley will setup a robust severe thunderstorm event for eastern and far southeastern Missouri late this Friday afternoon and evening. Most of the precipitation chances are east of our forecast area, and 06z CAMs keep all activity well east of Hwy. 63. Saturday, a few PV anomalies over the eastern Pacific setup multiple short-wave axes across the western CONUS that will increase the flow enough to move the the closed-low system into the Northern Great Lakes Region, developing a corridor of mid-level height rises from the Front Range into the Mississippi River Valley. Eventually this becomes a mid-level ridge axis that moves through the area, providing WAA with passage of a thermal ridge, meanwhile subsidence across most of the region through at least the last afternoon hours of Saturday will keep the early portions dry. This should also keep temperatures in the lower 80s across most of the forecast with upper 70s toward the Kirksville area. Later Saturday, H5 trough over western CONUs is progged to develop a negative tilt that may eject a localized vort maxima toward the southwest portion of our forecast area. Low-level flow response turns southerly ahead of this resulting in enhanced moisture transport, and could bring shower activity during the very late evening hours Saturday and overnight into Sunday. Primary H5 ridge axis should pass east of the region overnight or very early Sunday morning. By Sunday, broad H5 troughing is still progged over much of the Intermountain West to the Front Range. Deterministic GFS and ECMWF depict two vort maxima and closed-lows that attempt to develop, nearly depicting a Fujiwara Effect. Not completely confident this will pan out exactly as modeled, but is at least indicative that the propagation of the main trough axis stalls, providing the Central Plains to the Mississippi River Valley persistent southwesterly flow starting Sunday afternoon. Strong dCVA commences in the Front Range and High Plains Sunday afternoon resulting in strong surface cyclogenesis. This enhances low-level southwesterly flow across most of the Central CONUS, with southerly flow near the surface providing stronger theta- e advection. This starts to push a warm front across eastern Kansas to Central Missouri. Expecting persistent isentropic ascent across most of the theta-e transport axis to generate rain showers most of the day Sunday, helped by a few mid-level vort maxima ejecting from from the main trough west of the area. While theta-e advection will introduce instability, with MUCAPE values pushing above 2500 J/kg, strong cap remains in place as warm-nose pushes through. A few thunderstorms certainly can develop in this regime, but better shear and forcing remains west over Central Kansas for most of Sunday, thus largely limiting the potential for organized storms that could become severe. Confidence is high for measurable rain on Sunday, with most ensemble suites depicting over 90 percent chances for measurable rainfall Sunday afternoon and evening. Monday, expecting the H5 trough axis to slide further eastward into the Central Plains, with dCVA moving eastward tracking the surface cyclone further east. This will will provide better large scale ascent across our forecast area, and pushes the warm front toward the Iowa state line. High theta-e airmass settles in, with dewpoints progged to reach the upper 60s for areas along and south of Hwy. 36. Deepening surface cyclone should help to back surface winds, increase low-level flow, while strengthening mid and upper-level jet streak moves overhead increasing the deep layer shear across a strong warm-sector. This is shaping up to be a favorable severe thunderstorm environment, especially for areas along the warm front where surface troughing ahead of the main cyclone could occur. Deterministic GFS and ECMWF diverge in how the negative tilt of the H5 trough evolves Monday, and eventually on when it becomes a definitive closed-low. Therefore, this greatly impacts where the warm front surges and how expansive the warm-sector will be across our forecast area. With strong forcing and instability, damaging wind gusts and hail will be favorable with storms on Monday. The magnitude of shear values and potential hodograph structure could support a tornado threat, but there is not a strong consensus on how exactly the low-level wind field develops, and several other mesoscale factors cannot yet be determined. With the rainfall activity on Sunday, there is potential for differential heating boundaries to develop that could drastically alter the wind field. Aside from the severe storms threat, a stalling warm front within an area of broad synoptic scale ascent could lead to training showers/storms or perhaps an MCS, and in environment with PWATs pushing above 1.5 inches, likely leads to flooding issues. GEFS and other ensemble suites do currently depict over 50 percent probabilities for over 1.0 inch of rainfall on Monday, and that would be on top of whatever occurs from Sunday activity. Depending on how progressive the H5 trough becomes, Tuesday could be another day of severe storm development if the warm front remains north of the area, leaving a strong warm sector across the lower Missouri River Valley. Tuesday should eventually see a cold front push through and against a strong theta-e airmass. Continued strong mid and upper-level flow continues to provide deep layer shear favorable for organized activity. The main question for Tuesday is how long for our area does the threat persist. If the cold front surges early before stronger destabilization can occur, the threat may be short- lived. However, if the stalling of the system and warm front continues, could see activity continue later into the afternoon. Tuesday's severe weather environment will depend heavily on how Monday evolves, and what kind of recovery can occur. It is the type of setup where could see a lingering MCS, or activity that congeals into a MCV that greatly modifies the wind shear environment. It will be a few more days before we can really start to inspect mesoscale outcomes for Tuesday activity. Wednesday, ridge axis is progged to push across the western third of the CONUS, and should have enough flow to push any closed-low system eastward. Lingering rainfall from Tuesday activity is possible, with some ensemble members maintaining chances for measurable rainfall through Wednesday morning. There may be light activity that occurs after Wednesday of next week with few disturbances riding through the ridge, but overall probabilities are low at this time. && .AVIATION /06Z TAFS THROUGH 06Z SATURDAY/... Issued at 1152 PM CDT Thu May 15 2025 VFR conditions under mostly clear skies are expected to persist through the period. 10 knot SSW winds overnight will turn southwesterly by around 15z Friday, eventually becoming westerly and increasing with gusts up to 25 knots by around 21z Friday afternoon. && .EAX WATCHES/WARNINGS/ADVISORIES... MO...None. KS...None. && $$ DISCUSSION...Krull AVIATION...Williams