####018006442#### FXUS65 KPSR 161006 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 306 AM MST Fri May 16 2025 .KEY MESSAGES... 1) Gusty winds over the weekend resulting advisory level winds across portions of southeast California and locally elevated fire danger across eastern Arizona 2) Near normal temperatures into early next week before we see a warming trend and above (roughly 5-10 degrees) normal temperatures by late next week 3: Widespread Moderate HeatRisk is expected to return late next week and potentially continue through Memorial Day && .DISCUSSION... Weather Pattern Overview: Broad upper level troughing remains in place across the Western U.S. with heights across the Desert Southwest slowing rising allowing for some modest warming. Under sunny skies today, temperatures are expected reach into the lower 90s to around 95 degrees, or right around seasonal normals. The next weather system that will impact our region is currently off the coast of British Columbia, but it is forecast to quickly dive southeastward over the next 24-48 hours reaching central California and western Nevada by late Saturday morning and northern Arizona later Saturday evening. The main forecast concern with this next system will be the increase in winds across the region starting Saturday afternoon and lasting into Saturday night. Wind Advisories have been issued for the western half of Imperial Co. for this time with gusts in excess of 40 mph into the Imperial Valley which is likely to at least bring some lofted dust. Elsewhere across the area, winds Saturday afternoon and early evening are likely to gust between 20-30 mph at times, especially across the higher terrain. The Saturday disturbance is expected to shift northeastward out of our region Sunday morning, but there will be another one quickly following in its wake moving southward across the Great Basin Sunday before likely reaching northern Arizona by early Monday. The gradient will stay compact enough on Sunday to provide for another breezy day, but to a lesser degree compared to Saturday. Modestly cooler air will also spread into the area Saturday night into Sunday, lowering highs Sunday to between 85-90 degrees. There will also be a minor influx of lower level moisture into our area on Sunday, lasting through the first part of Monday. Despite this increase in moisture, the bulk of the system energy is expected to stay well to our north with any shower chances likely confined to the Arizona high country for Sunday and Monday. Monday should also bring some increased northerly breeziness focused down the Lower CO River Valley as drier air begins spread into the area from the north. Ensemble guidance agrees this second system will eject to the east northeast by Monday night with upper level ridging beginning to spread in from the west. As the upper level ridge gradually settles over the Desert Southwest during the middle part of next week, we are expecting to see a return of hot temperatures and highs likely reaching or topping 100 degrees as early as next Wednesday. The large scale weather pattern is expected to support keeping the ridge over the Southwestern U.S. for several days and likely through next weekend. There are still some model differences with the forecast H5 heights, but for now it still looks like the peak of the ridge may be around next Friday with some potential minor flattening of the ridge over Memorial Day weekend. The latest NBM forecast temperatures are very similar to what we have seen over the past couple of runs with highs peaking at or just above 105 degrees on Thursday and/or Friday, but with a slight lowering of temperatures over Memorial Day weekend. Either way, guidance continues to show Moderate HeatRisk developing by next Wednesday or Thursday. Forecast Confidence & Deviations: Confidence in temperature forecasts remains very good through Saturday with a bit lower confidence going into next week, especially Monday, as the second disturbance passes across northern portions of the region. If the system ends up digging farther south into Arizona, we are more likely to see highs closer to Sunday's compared to some slight warming the current NBM favors. Keeping in line with previous forecast packages, continued to adjust the winds higher over the weekend, focused more over southeast California. Forecast confidence for the hotter temperatures during the latter half of the forecast period remains good, but some changes to the temperatures (maybe a 1-3 degrees higher) may eventually occur, especially over the Memorial Day weekend. && .AVIATION...Updated at 0527Z. South Central Arizona including KPHX, KIWA, KSDL, KDVT; Southeast California/Southwest Arizona including KIPL and KBLH: No aviation impacts are expected through the next 24 hours. Winds at all terminals will follow typical diurnal trends, with speeds remaining at or below 10 kts through most of the TAF period. Afternoon gustiness can be expected in the Phoenix area, with gusts up to 15-20 kts at times. Clear skies will prevail. && .FIRE WEATHER... Today will bring another day of seasonably dry conditions with light winds before wind speeds increase markedly Saturday resulting in an elevated fire danger across the eastern districts. MinRHs will reach 10-15% today and Saturday across the eastern districts with readings across the western districts improving to 20-25% Saturday. Overnight recovery will be fair to poor with readings between 20-30% over the eastern districts and 30-50% over the western districts. Wind gusts of 20-30 mph will be common Saturday afternoon with localized stronger speeds across the western districts. 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...Wind Advisory from 2 PM Saturday to 7 AM PDT Sunday for CAZ562. Wind Advisory from 4 PM Saturday to 2 AM PDT Sunday for CAZ563- 566-567. && $$ DISCUSSION...Kuhlman AVIATION...Benedict FIRE WEATHER...Kuhlman ####018004344#### FXUS63 KDDC 161007 AFDDDC Area Forecast Discussion National Weather Service Dodge City KS 507 AM CDT Fri May 16 2025 .KEY MESSAGES... - Breezy and mild Friday - Storm chances return Saturday evening - Impactful severe weather potential in central Kansas shaping up Sunday afternoon and evening && .DISCUSSION... Issued at 202 AM CDT Fri May 16 2025 07z surface observations and upper air analysis shows a passing 500- 700 mb shortwave along the Kansas-Colorado border and an associated surface low and cold front roughly around Syracuse. A mid and upper level cloud deck is situated along and northeast of the surface low in northwest Kansas and the leading edge of the cooler air is entering into our northwest zones. Overall for today the progression of the wave and surface low should move into central and eastern Kansas during the late morning and early afternoon and the associated mixing and tighter pressure gradient should lead to breezy northwesterly winds during the day. Sustained winds will be 15-25 mph with gusts around 30 mph. Highs today should be around our seasonal averages as we get into the upper 70s to lower 80s. Tonight a weak backdoor front will move through southwest Kansas in response to a surface high in southern Nebraska and a developing surface low in northeast New Mexico. This boundary will set the stage for thunderstorm potential Saturday evening. Most of the day on Saturday should be dry but as the surface low deepens in northeast New Mexico with an upper level shortwave moving out of the desert southwest we should see increasing frontogenesis in central Kansas and good moisture advection as the winds turn back to a southeast direction during the afternoon. Short term models have the best area of moisture and associated lift moreso into central Oklahoma and southeast Kansas however with dewpoints forecast to reach into the lower to middle 50s in our south central counties we have a slight chance (20%) of storms mainly along and east of highway 283 Saturday night into Sunday morning. Sunday is showing increasing confidence in an impactful severe weather event for central Kansas. In our county warning area specifically the areas that are showing the higher risk of impactful severe weather would be along and north of a Pratt to Ness City line. Long range ensembles are showing a large longwave trough in the Rockies turning negatively tilted by Sunday afternoon with strong PVA entering into southwest Kansas by late in the afternoon on Sunday. At the surface a low develops in eastern Colorado with an associated warm front and large area of moisture along and north of the warm front which is situated roughly from Pratt to near Goodland. South of the front a strong dryline will move through southwest Kansas and based off of NBM probabilities of dew point temperatures greater than 55 degrees we see that areas from Dighton to Dodge City to Ashland on west are 10% or less (negating any storm or severe threat) and areas from Medicine Lodge to Ness City on east are 70-90%. Bulk shear values are forecast to increase to 50 kts as the 850 mb winds increase after 21Z. Skew t soundings are showing a shallow moist layer with drier mid levels in the 700 mb range and hodograph soundings show good veering with height and turning almost straight towards the anvil layer. The cap should weaken during the afternoon as the much warmer and drier air moves into central Kansas. All this is to say that any thunderstorm development with this setup we see 3 days out will have an environment for large hail (>2 inches) with some potential for giant (up to softball sized) hail and tornadoes in central Kansas. && .AVIATION /12Z TAFS THROUGH 12Z SATURDAY/... Issued at 507 AM CDT Fri May 16 2025 VFR flight category for all terminals during the next 24 hours. Winds will pick up after 14Z at all terminals sustained at 15 kts with gusts in the 25-30 kt range through 00Z Saturday. Winds should quickly diminish after 00Z to below 12 kts. && .DDC WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Tatro AVIATION...Tatro ####018006934#### FXUS66 KPDT 161009 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 309 AM PDT Fri May 16 2025 .SHORT TERM...Today through Sunday...Satellite imagery tonight shows a weak shortwave pushing light rain showers across the intermountain PacNW, with skies gradually clearing across the western third of the forecast area. The shortwave will exit the region later this morning, with the bulk of shower activity diminishing area-wide. Light orographic showers will continue across the Cascades, Blues, and Wallowas through this afternoon as a northwest flow aloft develops behind the shortwave exit. By this evening, a brief dry period will develop as flow aloft turns more zonal, then to the southwest ahead of an upper trough approach. Tonight, an upper trough will arrive to the PacNW, the first in a series of upper low pressure features that will impact the region. Shower chances along the Cascades and the eastern mountains will increase through the overnight hours into tomorrow morning as the trough moves inland. Weak elevated instability with modest mid- level lapse rates will develop out ahead of the trough axis tonight, allowing slight chances (around 15%) of isolated thunderstorms to develop mainly over the mountainous terrain of Grant and eastern Crook counties. The upper trough will continue to dive southeast into the Great Basin Saturday morning, allowing the next upper trough to dive across the PacNW Saturday through Sunday. Guidance does indicate that the upper trough will develop into a closed low over the PacNW during it's southeastward descent, though there are minor differences in the timing and position of the closed low. Nonetheless, the second upper low feature will continue to bring shower activity area-wide the first half of Saturday, with shower activity diminishing across the lower elevations as the upper low moves overhead through Saturday night and Sunday morning. During the day Saturday, increasing surface based instability(200-500 J/kg) and modest low to mid level lapse rates will result in isolated to widely scattered thunderstorm chances (15-30%) mixing in with showers across the forecast area Saturday afternoon through the late evening (confidence 50-70%). Through Saturday night, there is a 65-90% chance for rain accumulations of 0.25 inches across the mountain zones, including the Grande Ronde valley...55-85% chance for 0.1 inches in the lower elevations. Winds will increase through the Cascade Gaps and into portions of the Columbia Basin and Central OR as cold air advection under the upper trough/low passages will result in a strengthening of the cross-Cascade surface pressure gradient. Winds Saturday will increase to 20-30mph with gusts up to 40mph through the Cascade gaps, and 15-25mph with gusts up to 35mph elsewhere in the lower elevations (confidence 70-80%). Sunday, rain/snow showers will mainly be confined to the Cascades, Blues, and Wallowa county as the upper low continues to push southeast. By Sunday late afternoon and evening, shower activity will diminish across the aforementioned areas as the upper low crosses into the Great Basin to the southeast. Surface winds will continue to strengthen Sunday, with a 75-90% chance that wind gusts will reach or exceed 45mph through the Kittitas valley and a 60-75% chance through the eastern Columbia River Gorge. Elsewhere in the lower elevations, winds will continue to be 15-25mph with gusts up to 35mph (confidence 65-80%). Lawhorn/82 .LONG TERM...Monday through Friday...Models key in on a relatively progressive pattern next work week, albeit one without much in the way of significant sensible weather impacts as the synoptic pattern looks to be zonal in nature. As a result, the weather threats next week look to be comprised of breezy downslope winds, slight chance to chance PoPs for our mountain zones, and generally seasonable temperatures, save for early Monday morning when northerly flow trailing a departing system may make for a potential overnight freeze across some of our elevated valley zones. The synoptic pattern evolves as thus: a low digging into the Four Corners region will make for northerly flow heading into Monday, leading to a chilly morning as central Oregon, the Grande Ronde Valley, and the Wallowa Valley all stand to see a chance of freezing temperatures (20-30%, 10-20%, and 50-60%, respectively). Flow aloft then turns zonal, before a shortwave develops off the Pacific coast Tuesday into Wednesday, introducing a slight amount of instability, enough to trigger low-end thunderstorm chances (10-20%) for the eastern mountains Tuesday afternoon, but the threat looks to be isolated given the lack of moisture advection with this shortwave. Models start to diverge Wednesday onward, with ensembles generally suggesting a return to zonal conditions and thus benign weather for the rest of the period, however the deterministic GFS and ECMWF do suggest the possibility of shortwaves embedded within the zonal flow that could lead to at least slight widespread PoPs for the forecast area. Given that ensemble guidance doesn't currently reflect this, however, confidence in this occurring is low. Such patterns generally lead to breezy conditions downslope of the Cascades, so expect the Cascade Gaps and east slopes to see recurring days of gusts over 25 mph so long as we remain under zonal flow. Some ensemble members suggest high pressure building in by the tail end of the period, which could lead to a warming trend, however other members insist on keeping at least a weak zonal pattern in place. Confidence in the forecast Wednesday and beyond remains low (30-40%). Evans/74 && .AVIATION...12z TAFs...VFR conditions expected through the period. Light rain will end early this morning, leaving us with partially clearing skies during the day at sct-bkn 5-10 kft. Clouds will build back in this evening, becoming ovc at 10-15 kft by nightfall. Winds will generally be W to SW, except NW for DLS, BDN, and RDM, at less than 15 kts. Evans/74 && .PRELIMINARY POINT TEMPS/POPS... PDT 66 47 64 43 / 20 20 80 60 ALW 65 49 65 44 / 50 10 70 70 PSC 71 49 71 46 / 10 10 60 50 YKM 70 50 68 43 / 10 10 50 10 HRI 70 48 69 45 / 10 20 70 40 ELN 65 46 64 42 / 10 20 60 20 RDM 65 43 61 36 / 0 20 50 20 LGD 59 42 58 40 / 40 20 90 80 GCD 62 43 57 37 / 10 50 100 80 DLS 68 50 68 47 / 10 20 50 10 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...82 LONG TERM....74 AVIATION...74