####018005080#### FXUS66 KPQR 170925 AFDPQR Area Forecast Discussion National Weather Service Portland OR 225 AM PDT Sat May 17 2025 .SYNOPSIS...Periods of light rain showers expected through the weekend and into early next week. Expect temperatures to remain slightly below average during this period. Rain showers along with a 10-20% chance of thunderstorms this afternoon afternoon. Lingering showers into Sunday, though most areas likely drier. Temperatures trending warmer, upper 60s to lower 70s, toward the end of next week. && .DISCUSSION...Tonight through Friday...Shower activity is increasing across the region as a shortwave trough is digging into the PacNW coast. Heaviest shower activity is expected through the morning as the deepest are of moisture comes onshore. Shower activity will continue into the afternoon as another disturbance approaches Vancouver Island. There is also a slight chance (10-20%) for thunderstorms this afternoon and evening. No strong thunderstorms are expected. Shower activity is expected to be more persistent across the higher terrain of the western slopes of the Cascades. Rainfall totals through tonight across the lowlands are expected to fall between 0.10-0.40 inches, generally higher totals across the northern portion of the forecast area. Higher totals across the Coast Range expected with totals between 0.25-0.75 inches expected. Highest totals across the Cascades and Cascade Foothills, generally 0.75-1.25 inches with locally higher amounts. Conditions trend drier on Sunday, though light showers will persist into the afternoon as the disturbance over Vancouver Island becomes a cut-off low east of the Cascades, centered over eastern Washington. Weak ridging will build into the region, supporting partly sunny skies during the afternoon, though temps will remain 5- 8 degrees below average, topping out in the low 60s inland. Model agreement is increasing for another weak system to cross the region on Monday with another round of light rain showers expected. Totals of 0.10-0.20 inches expected across much of the are with totals as high as half an inch across the higher terrain of the Cascades. Zonal flow with another embedded disturbance passing to the north may maintain light showers into Tuesday. Agreement degrades middle to end of next week with cluster analysis showing split pretty equally between ridging and troughing. NBM guidance though continues to suggest temperatures gradually warm closer to average toward the latter part of next week, along with precipitation probabilities generally 15% or less Wednesday through Friday. -Batz && .AVIATION...Weak front is moving across northwest Oregon as of 09z Sat accompanied by numerous rain showers, producing IFR conditions at the coast and mainly MVFR with a few pockets of IFR inland. Expect these conditions to persist through around 21z Sat, after which time conditions will trend back towards VFR as showers start to diminish in coverage. There remains a 15-20% chance of thunderstorms across the Willamette Valley today. Any of these storms will be capable of producing small hail, gusty winds, and temporarily reduced cigs and visibilities, but probabilities are too low for inclusion in TAFs at this time. Winds will shift northwesterly and increase to 10-15 kt with a few gusts to 20 kt behind the front 18-21z Sat, diminishing again 03-06z Sun. PDX AND APPROACHES...Mainly MVFR in rain showers through 21z Sat, improving to VFR thereafter as showers diminish in coverage. Wind generally W-SW at or below 5 kt through 21z Sat, shifting NW and increasing to 10-15 kt with a few gust to 20 kt through 03-06z Sun. /CB && .MARINE...Fresh northwest breezes will develop over the coastal waters today as a weak front moves inland along the Oregon Coast early this morning. This will produce low end Small Craft Advisory conditions through early Sunday as winds gust to around 25 kt. Seas will generally be in the 6-8 ft range, dominated by a mid period westerly swell on the order of 6-7 ft at 10-11 seconds. Calmer conditions are expected during the day on Sunday as high pressure moves overhead, bringing lighter west winds as the westerly swell persists at 5-6 ft. Winds will shift southerly as the next front approaches the waters Sunday night into Monday, likely warranting another round of headlines as models depict a 80-90% probability of wind gusts to 25 kt through Monday evening. Seas look to increase towards the middle of next week as westerly swell builds to around 10 ft on Tuesday. /CB && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 11 AM this morning to 11 AM PDT Sunday for PZZ210-251>253-271>273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland ####018006437#### FXUS65 KGJT 170927 AFDGJT Area Forecast Discussion National Weather Service Grand Junction CO 327 AM MDT Sat May 17 2025 .KEY MESSAGES... - Warm and breezy conditions are expected today, with a chance for isolated showers or storms on the higher terrain north of I-70. - Southeast Utah and southwest Colorado will see elevated to critical fire weather conditions this afternoon, where fuels have been deemed critical. A Red Flag Warning remains in effect for southeast and east-central Utah. - Cooler and unsettled conditions return for Sunday through Tuesday, with mountain snow and valley rain expected. && .SHORT TERM /THROUGH SUNDAY/... Issued at 326 AM MDT Sat May 17 2025 Mid and upper level moisture is streaming across the northern half of the region this morning, spawning increased cloud cover and virga showers. Thus far, little if any precipitation has reached the ground despite the returns on radar, but some stronger, gusty winds have been recorded. This increased moisture and cloud cover has resulted in milder temperatures this morning, particularly for areas north of the San Juans. To the south, a punch of drier air is working in, resulting in comparatively lower dew points and temperatures about where they were at this time last night. This punch of dry air is expected to bring single digit and low teens humidity values to southeast Utah and southwest Colorado this afternoon. In addition, southwesterly winds will be on the increase as the trough to our west strengthens and the pressure gradient begins to tighten up aloft. With gusts of 25-35 mph expected, this will result in elevated to borderline critical fire weather conditions this afternoon where fuels are critical. A Red Flag Warning is in effect for southeast and east-central Utah (UT Fire Weather Zones 490 and 491) from noon to 8PM. While fuels are currently not deemed critical across most of southwest Colorado, that doesn't mean that localized critical fire weather conditions aren't possible. Caution is urged and outdoor burning is not recommended given the drier and breezy to windy conditions. Enough moisture will remain in place across northwest Colorado and northeast Utah to result in a few orographic shower over the higher terrain, with maybe a slight expansion in coverage this evening as a small wave in the southwesterly flow moves through. Otherwise, breezy, warm, and quiet conditions will be the name of the game today. Temperatures will climb to around 5 degrees above normal. Winds will continue to pick up through the night as the trough strengthens and an 70-80 knot jet moves overhead. However, moisture will also be on the increase. So while tomorrow will see stronger winds, the fire weather concerns will be limited. Shower activity is expected to break out around daybreak tomorrow, favoring the higher terrain along and south of I-70 as the best energy at the base of the trough tracks over the Four Corners. Additionally, a cold front will push through during the afternoon, bringing much cooler temperatures, with highs expected to be around 10 degrees cooler than today, and more widespread precipitation. With moisture and a much cooler airmass in place, accumulating snow above 9K feet is expected. At this point, with this event lasting through Tuesday morning, snow totals are looking borderline advisory. There's still enough uncertainty that I am holding off on issuing highlights with this package. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... Issued at 326 AM MDT Sat May 17 2025 A deep upper-level trough will be overhead on Sunday night, bringing widespread precipitation across the CWA, with mountain snow and valley rain. Uncertainty grows on Monday as a northern closed low descends southwards through the trough. Lacking moisture with this low (PWAT's 90-130% of normal) will result in primarily orographically-driven showers, though the further reduced temperatures associated with the system would favor more mountain snow and valley rain as snow levels drop to around to 7.5-8.5 kft. The rapidly evolving upper-level pattern regarding the slow-moving trough and the southwards-moving closed low leaves the early-week weather difficult to pinpoint. One way or another, widespread precipitation favoring higher terrain where orographics can better support storms is expected to occur. However, timing and intensity remains unclear, and future forecast discussions should provide more clarity on the details as more short-range model guidance becomes available. For later in the period, models are still indicating ridging trying to build into the Desert Southwest, resulting in a return to warmer and drier conditions. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1126 PM MDT Fri May 16 2025 A stream of upper level moisture from the Pacific will keep mid and high level clouds across the northern two thirds of eastern Utah and western Colorado through the night and into the morning. A few showers are accompanying these clouds, but little, if any, precipitation is reaching the ground. If anything, these virga showers will produce gusty and erratic winds. Gusty southwesterly winds will pick up tomorrow afternoon, with peak gusts of 20-30 knots expected. VFR conditions are expected to prevail for the next 24 hours. && .FIRE WEATHER... Issued at 326 AM MDT Sat May 17 2025 Dry and breezy conditions are expected this afternoon across southeast Utah and southwest Colorado, resulting in elevated to critical fire weather conditions. A Red Flag Warning remains in place for Utah Fire Weather Zones 490 and 491. Stronger southwesterly winds with gusts up to 40 mph are expected tomorrow, but enough moisture will be in place to keep humidities above critical thresholds. Cooler and wetter conditions are expected early next week, before a return to warm and dry weather Wednesday onward. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...Red Flag Warning from noon today to 8 PM MDT this evening for UTZ490-491. && $$ SHORT TERM...BGB LONG TERM...TGJT AVIATION...TGJT FIRE WEATHER...BGB ####018005668#### FXUS66 KSGX 170929 AFDSGX Area Forecast Discussion National Weather Service San Diego CA 229 AM PDT Sat May 17 2025 .SYNOPSIS... Cooler conditions with increased cloud cover and stronger, gusty westerly winds expected over the weekend. Low clouds will fill in much of the coastal basin each night and morning. There are chances of light rain and drizzle west of the mountains this morning and tonight into Sunday morning. Warmer conditions with a shallower marine layer is expected for next week. Periods of locally gusty offshore winds are expected Monday morning through Monday afternoon. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... This morning...A closed upper low over northern Mexico is ejecting to the northeast from the base of a large-scale trough over the Desert Southwest. This is in response to a shortwave trough moving southeast in the mean northwest flow over the west coast. This has resulted in the marine layer now becoming about 3000 feet deep with low clouds covering most of the region west of the mountains. There is a good chance that the saturated layer becomes thick enough to produce patchy drizzle west of the mtns this morning. As that shortwave continues to move southeast, it becomes a closed upper low over the Great Basin by Tonight. This system will bring stronger westerly winds to SoCal today through tonight. The winds have begun to strengthen and the wind-prone locations in the mtn passes have begun to report wind gusts of 35-50 mph. Winds will peak this afternoon/evening with gusts of 45-55 mph...locally up to 65 mph in the windiest locations. The gusty winds could bring areas of blowing dust and sand in the deserts, reducing visibility at times. This reinforcing shortwave could produce enough dynamic forcing to convect what little moisture there is, and high-resolution models are showing small chances for Isold-SCT light showers from late this morning through tonight. Rainfall totals are unlikely to exceed 0.10 inch from the mtn slopes to the coast. Today will be a cool day, with daytime high temperatures a few degrees below normal in the coastal areas and deserts to as much as 15 degrees below normal in the inland valleys. Dry with a warming trend beginning on Sunday as low pressure moves eastward into the Rockies and weak high pressure builds over the west coast. A surface high moving into the Great Basin will bring periods of weak offshore flow on Monday, with locally gusty northeast to east winds. Current guidance shows the offshore winds peaking late Monday morning with local wind gusts of 35 to 40 mph on the coastal slopes of the San Bernardino Mtns, in the northern parts of the IE and in the Santa An Mtns. The offshore winds will weaken on Monday evening. Under the weak high pressure aloft, temperatures will continue to rise through midweek and Wed and Thu are likely to be the warmest days with daytime high temps reaching the mid to upper 90s in the IE on both those days. The marine layer will maintain less of a presence with day-to-day variations on the amount of low clouds/fog during the nights and mornings but daytime temperatures will reach the mid 70s near the coast. Temperatures will again trend lower for next weekend as a low pressure trough approaches from the northwest but there isn't much confidence in the details of the forecast due to the spread among model solutions. && .AVIATION... 170900Z...Coast/Valleys...Satellite shows the marine layer has managed to push all the way up to the mountains with bases ranging from 1500-2300ft MSL and tops to 3000ft. Patchy drizzle is possible through 18Z, especially for inland valleys, which could locally lower VIS to 4-6SM and CIGs to 1000-1500ft MSL, but significant/prolonged impacts unlikely. Partial clearing will occur for eastern valleys after 18Z, but most other areas will remain BKN- OVC all day, though CIGs rise to 2000-3000ft MSL and prevail into Sunday morning. More scattered light showers/drizzle expected after 00Z Sunday. Mountains/Deserts...SCT high clouds prevail. West to southwest gusts 25-40kts over the desert foothills and through passes will become more widespread through the deserts and strengthen to 35-55kts after 17Z, producing strong up/downdrafts in the lee of mountains such as vcnty KPSP. BLDU likely 20Z Saturday through 08Z Sunday, primarily in the deserts and Coachella Valley, where VIS may fall below 3SM at times. && .MARINE... Onshore winds gusting near 20kts near San Clemente Island late this afternoon into early Sunday may lead to some choppy seas in the outer waters. Otherwise, no hazardous marine conditions expected through Wednesday. && .BEACHES... Elevated surf will impact beaches Sunday and early Monday. Expected surf of 4-6 feet would produce a high rip current risk. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory from noon today to 2 AM PDT Sunday for Apple and Lucerne Valleys-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass near Banning. PZ...None. && $$ PUBLIC...PG AVIATION/MARINE/BEACHES...Zuber