####018007214#### FXUS63 KDLH 152017 AFDDLH Area Forecast Discussion National Weather Service Duluth MN 317 PM CDT Thu May 15 2025 .KEY MESSAGES... - A line of severe thunderstorms is expected to move northeast across northwest Wisconsin and northeast Minnesota this afternoon and evening. Damaging winds, large hail, and isolated tornadoes are the threats. - Rain begins today with a brief break behind today's storms, with widespread lighter rain returning tonight through Saturday morning. Up to an inch and a half of rain possible. - Cooler weather for the weekend with Saturday night and Sunday night lows lows near freezing for portions of the region with frost expected. Even a little snow will mix in for the Arrowhead Saturday night into morning. && .DISCUSSION... Issued at 317 PM CDT Thu May 15 2025 Rest of Today - This Evening: Deep low pressure centered over southeastern North Dakota will largely spin in place through this evening as an occluded front lifts northeast through the Northland. Along and north of this front, a narrow warm sector has developed in central Minnesota down to the Twin Cities metro area, with MLCAPE of 1000-2000 J/kg and effective bulk shear of 35 to 45 kt. The 18Z MPX sounding depicts a favorable hodograph for development of low- level rotation, with 0-1km SRH of 211 m^2/s^2 and 0-3km SRH of 306 m^2/s^2. Scattered pre-frontal discreet storms have developed north of the front in central MN where this environment will be favorable for locally damaging wind gusts, large hail (up to 1.5 inches), and a tornado or two through the afternoon. Eventually as the front moves northward, hi-res model guidance favors storms in the Twin Cities metro area growing upscale into a line of storms (QLCS) and tracking northeast through the Northland, first in central and east-central MN by late afternoon and then through north-central MN, northwest WI, and the Arrowhead this evening. As the afternoon progresses, the MLCAPE should build to 1800-2800 J/kg from the Brainerd Lakes to northwest WI by late afternoon/early evening while shear remains strong, as well as 0-1km and 0-3km SRH continuing to remain favorable for low-level rotation and potential for a couple tornadoes with any mesovorties that develop in the lines of storms that move through. Damaging wind gusts of 60-70 mph become increasingly likely with the line of storms later this afternoon into evening in this strongly sheared and buoyant environment, particularly in bowing segments of the storms. Large hail up to half-dollar size is also possible, particularly in northwest WI through early evening before better lapse rates aloft diminish. The steeper lapse rates in central/northeast MN tend to remain ahead of the line of storms, so while large hail (quarters) are still possible there, the threat is lesser than in NW WI. By mid-late evening, instability should begin to wane as storms move into the Iron Range, northern MN, and the Arrowhead, so the severe threat should gradually drop off towards the 8-10pm timeframe as storms move into those locations. Therefore, expect the tornado potential to drop off by the time storms reach the Iron Range, with the severe wind and hail threats dropping off as storms near the International Border. Tonight - Friday night: Expect a lull in precipitation behind the line of storms later this evening and tonight before more widespread, lighter rainfall overspreads the Northland as the low-pressure treks east across northern MN and Lake Superior. Steeper low-level lapse rates in central MN could even be sufficient enough to produce limited instability and a few thunderstorms embedded in the rain there. Rainfall totals for this afternoon through Friday night range from around 0.4" to around 1.25", with the highest amounts (0.75-1.25") extending from St. Cloud to the Brainerd Lakes, into the Twin Ports and parts of the North Shore up to Silver Bay. This Weekend - Next Week: Spottier light rain lingers on the back side of the departing low pressure for Saturday into Saturday night, with the potential (20-40%) for light snow to mix in over the Arrowhead Saturday night as colder air works in, though no snow impacts are expected. Seasonally cool temperatures, with highs in the 50s to mid 60s and lows largely in the 30s persist Saturday through early next week as a prolonged period of easterly surface winds persist. There are frost and freeze concerns for Sunday and Monday mornings, possibly the Arrowhead Tuesday morning as temperatures drop into the low to mid 30s. Another rain system is possible Tuesday - Tuesday night, but the track of the low could trend just south enough that the Northland could miss out on more widespread rain chances. Rain chances range from 30-60%, highest in the southern half of the Northland. Beyond early next week, expect a gradual warm up again as the week progresses. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1255 PM CDT Thu May 15 2025 Dense fog near DLH has retreated to Lake Superior and is no longer impacting the terminal. Low pressure to our southwest will push a line of storms through the region this afternoon and evening, moving from southwest to northeast. This line will start out near BRD around 20Z and exit around CKC around to cross from southwest to northeast starting around 19Z near KBRD and exiting around 03Z near KCKC. Strongest storms should be across NW WI back into central Minnesota where hail and strong to severe winds could accompany the strongest storms. Lightning and gusty winds will accompany all storms. Winds will turn from easterly to southerly this evening, and remain southerly into Friday. && .MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/... Issued at 317 PM CDT Thu May 15 2025 Dense Fog continues on Lake Superior into this evening, with a Dense Fog Advisory in effect for the Outer Apostles and far western Lake Superior. A short period of gales is forecast along the north shore through early this evening, with small craft advisories until late evening as well before winds weaken on the Lake. Strong to severe storms also move across western Lake Superior this evening, with large hail and gusty winds up to 40-50 kt as the main threats. Storms exit later this evening. Winds remain easterly to southeasterly into Friday and then gradually veer to northwesterly Friday night into Saturday. For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt. && .DLH WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. MARINE...Small Craft Advisory until 10 PM CDT this evening for LSZ121- 145>148-150. Dense Fog Advisory until 10 PM CDT this evening for LSZ140>146- 150. Gale Warning until 8 PM CDT this evening for LSZ140>144. && $$ DISCUSSION...Rothstein AVIATION...Rothstein MARINE...Rothstein ####018006089#### FXUS65 KPSR 152015 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 115 PM MST Thu May 15 2025 ...Key Messages 1) Gusty winds over the weekend resulting in a locally elevated fire danger 2) Increased odds for above normal temperatures and widespread Moderate HeatRisk returning late next week... .DISCUSSION... Weather Pattern Overview: Broad, weakly cyclonic flow lingers over the SW Conus as a closed, occluded low pressure system lifts into the Upper Midwest. The weakness left in the midtropospheric flow over the forecast area from this exiting system will quickly be filled over the weekend by a series of Pacific negative height anomalies intensifying into an amplified longwave western trough. The magnitude of the attendant Pacific jet during this meridional transition will ensure robust shortwave energy and notable height falls migrate into much of Arizona. The timing and juxtaposition of height falls and jet core carving out the trough base will support very gusty winds throughout the weekend, but particularly Saturday afternoon/evening across SE California where parameters align nearly optimally. As such, advisories will almost certainly be necessary in the typical wind prone locations of Imperial County. These gusty winds combined with seasonally low humidity values will also result in an elevated fire danger, though more limited wind speeds in south-central Arizona Saturday and higher moisture sweeping through the region Sunday may preclude more critical conditions. Ensemble membership remains in good agreement depicting several vorticity centers pivoting through the longwave trough with one notable and final trailing wave digging into northern Arizona Monday. Given the inland trajectory of this entire series of shortwaves, moisture will be extremely limited with boundary layer mixing ratios never exceeding 5 g/kg. However, given the unusual depth of the trough and magnitude of the cold core, a few showers may be squeezed out over higher terrain areas. On the other hand, recent operational models have shifted the jet streak and cold core slightly further north resulting in a forecast of a large midlevel capping inversion locked over the southern half of Arizona. If this model trend comes to fruition, it would be all but impossible for anything other than outflow winds to propagate into lower elevations. While some subtle midlevel weakness in the height field may hold over the Southwest during the latter half of the week, ensembles are far more resolute in building stronger ridging over northern Mexico and SW Conus. Some of the more extreme members have been highlighting H5 heights around 594dm, however the preponderance of output suggests heights closer to 588dm. As a result, widespread moderate HeatRisk should evolve towards the end of next week with temperatures nearly 10F above normal. Should any of the more anomalous solutions be realized (and it could be argued that would be a likely outcome given the pattern progression), this could be the first vestiges of major HeatRisk with temperatures 15F above normal yielding extreme HeatRisk over the holiday weekend. Forecast Confidence & Deviations: Good confidence in temperature forecasts exists the next couple days, but then deteriorates significantly early next week depending on how far south the cold core migrates. Mandated NBM forecasts have bumped warmer based mainly on changes in the operational members, but could flip flop back based on future model iterations. Feel the automated NBM winds over the weekend are somewhat underforecast and have made some minor increases during peak mixing hours. Spurious POP and QPF grids were substantially reduced this cycle, however did have to make some minor adjustments based on unrealistic model artifacts. Average confidence exists with respect to temperatures towards the end of this forecast period, but would not be surprised if actual readings were even warmer than the current automated NBM output. && .AVIATION...Updated at 1728Z. South Central Arizona including KPHX, KIWA, KSDL, KDVT: Winds will follow their typical diurnal tendencies through the TAF period. Westerly winds will continue throughout the afternoon with speeds generally aob 8 kt. Some occasional gusts into the mid-teens will be possible this afternoon. Late tonight into the overnight period winds are expected to shift out of the east, with speeds aob 5kts. During this time light and variable to calm winds can be possible. Skies will be mostly clear. Southeast California/Southwest Arizona including KIPL and KBLH: Current VRB winds will soon establish out of the E at KIPL and SSE at KBLH. Winds are expected to shift to a more westerly component by late tonight at both terminals. Wind speeds at both terminals will generally be aob 7 kt. Skies will be mostly clear. && .FIRE WEATHER... With dry conditions prevailing through next week, winds will increase in speed over the weekend yielding an elevated fire danger with locally near critical conditions. MinRHs will mostly fall in a 10-15% range through Saturday before a cooler and somewhat more moist airmass keep minimum readings in a 15-25% range Sunday and Monday. Poor to fair overnight recovery of 20-50% will improve closer to a 35-60% range early next week. Winds will be most pronounced in western districts Saturday with gusts 30-40 mph, then translating into eastern districts Sunday albeit with somewhat weaker speeds. Very warm and dry weather will return during the middle of next week, however wind speeds will be much weaker as high pressure starts building into the region. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...18 AVIATION...Ryan FIRE WEATHER...18 ####018004817#### FXUS63 KOAX 152020 AFDOAX Area Forecast Discussion National Weather Service Omaha/Valley NE 320 PM CDT Thu May 15 2025 .KEY MESSAGES... - Windy today and windy again Friday with gusts of 40-50+ mph. - A stormy pattern develops Sunday-Wednesday with a good chance for widespread rainfall, and potentially multiple severe weather episodes. - Don't overlook the potential for heavy rainfall and flash flooding, especially Sunday-Tuesday. && .DISCUSSION... Issued at 320 PM CDT Thu May 15 2025 We have scattered clouds across the region this afternoon as a weak shortwave moves across the area. Radar shows a few isolated showers and storms developing from the cu field across central Nebraska. For this reason, we've added a slight chance of showers and storms across more of northeast Nebraska than previously in the forecast. Instability combined with any outflow boundaries that may develop could lead to a couple funnel clouds or even a landspout this afternoon. A strong low pressure system is located to our north over the eastern Dakotas, creating a strong pressure gradient across our area this afternoon. This is the cause of the strong westerly winds we're seeing this afternoon, with gusts to 50 mph. This evening we will see the boundary layer decouple a bit bringing wind speeds down to more reasonable levels, but mid-morning on Friday these winds will ramp back up for another day of strong westerly winds on Friday. The Low finally exits stage right Friday night into Saturday allowing winds to relax with high pressure bringing back sunny skies. Winds will be light out of the northwest helping to keep temperatures mild with highs in the 70s. Ridging buckles up over the Central Plains this weekend as our next trough digs into the Four-Corners region. Sunday we'll see a strong surface low start to develop along the lee side of the Rockies in eastern Colorado which will pull a warm front north across our area Sunday evening. Models differ on timing of this frontal passage, with a greater severe threat if this front lifts north during the day, but still some threat overnight even if it waits to lift north until Monday morning. In the latter case, we'd have more of an elevated storm threat with potential for heavy rain, hail, and damaging winds. Monday looks like the day with higher potential for severe weather. Machine Learning algorithms are all highlighting our area for potential as the warm sector of this Low will be located across much of southeast Nebraska into southwest Iowa. This area will see significant destabilization during the day with a dry line providing the trigger for initially discrete storms during the afternoon. All severe modes are in play for Monday, with the primary mode of failure being how far north the warm front gets Sunday night-Monday morning (possibly limiting the severe threat to areas to our south). Monday is certainly the day to watch for severe weather. Showers and storms will linger into Tuesday as we remain under the upper-level Low, with potential for cold-core funnels. We don't see the system completely exit our area until possibly as late as Wednesday afternoon, with scattered showers continuing until then. We see a transition back to northwesterly flow toward the second half of the week which may bring slightly cooler than normal temperatures going into next weekend. We'll need to monitor for potential flooding and flash flooding at times with these systems Sunday-Tuesday as we could see some training storms develop. The WPC is highlighting our area for potential excessive rainfall which could lead to flash flooding. && .AVIATION /18Z TAFS THROUGH 18Z FRIDAY/... Issued at 1211 PM CDT Thu May 15 2025 VFR conditions will hold through the TAF period, though dust could potentially reduce visibility at KLNK and KOMA at times through this afternoon. Strong westerly winds today gusting to 40 to 45 kt will weaken this evening after 00Z, and become more southwesterly overnight. Winds will pick back up out of the west around 14-15Z on Friday with gusts again to 40 kt likely. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Wind Advisory until 8 PM CDT this evening for NEZ011-012- 015>018-030>034-042>045-050>053-065>068-078. Wind Advisory from 7 AM to 9 PM CDT Friday for NEZ011-012- 015>018-030>034-042>045-050>053-065>068-078. IA...Wind Advisory until 8 PM CDT this evening for IAZ043-055-069- 079-090. Wind Advisory from 7 AM to 9 PM CDT Friday for IAZ043-055-056- 069-079-090. && $$ UPDATE...Mead DISCUSSION...McCoy AVIATION...McCoy