####018005302#### FXUS65 KBOI 131022 AFDBOI Area Forecast Discussion National Weather Service Boise ID 322 AM MST Sat Dec 13 2025 .SHORT TERM...Today through Monday night...High pressure will remain over the region through the weekend, with a surface inversion developing in valleys. This will bring air stagnation to sheltered valleys, with low mixing heights and light winds trapping pollutants and aiding in patchy valley fog formation overnight tonight and tomorrow. Temperatures will remain about 10-20 degrees above normal through Monday, with a slight cooling trend beginning Sunday as yet another atmospheric river moves into the Pacific Northwest on Monday. This plume of moisture paired with warm southwest flow will bring widespread precipitation and high snow levels around 7500-8000 feet MSL. This system will begin the pattern shift for next week and aid in scouring out any lingering effects from stagnant air this weekend. Rain will be the predominant precipitation type for most of the region, with elevations above about 8000 feet MSL seeing minor snow accumulation on Monday. Expect anywhere from a few hundredths to up to a quarter of an inch of rain on Monday, with higher elevations in Baker County and West Central seeing the heavier precipitation. .LONG TERM...Tuesday through Saturday...Strong zonal flow will dominate as a Gulf of Alaska trough approaches the forecast area on Tuesday. This westerly flow will ingest the next round of considerable subtropical moisture as the trough enters the Pacific Northwest. It is forecast to arrive in E Oregon and SW Idaho by mid to late Tuesday, increasing winds and precipitation chances area- wide. Quick to follow will be a vigorous cold front Tuesday night into Wednesday which will continue the widespread precipitation while increasing surface winds further. Temperatures should begin mild, at approximately 15-20 degrees above normal, just ahead of this system Tuesday, but will lower by 5-10 degrees on Wednesday with the cold front. However, the brunt of the cold airmass is anticipated to remain farther north over Canada, WA, and the ID panhandle as the trough passes through. In correlation, snow levels will drop from 6500-8000 feet MSL on Tuesday down to 3500-5500 feet by Wednesday, allowing snowfall to accumulate in the mountains and some foothills. A weak ridge is forecast to develop behind the aforementioned trough late Wednesday into Thursday morning, potentially providing a brief respite from precipitation. However, the next trough is expected to follow by mid-day Thursday. This trough will be associated with a more prominent atmospheric river, distributing another round of hefty precipitation across the region. Snow levels across E Oregon/SW Idaho will initially begin around 5500-7000 feet ahead of the accompanying cold front, then lower to 4000-6000 feet behind the front arriving on Friday. Another boost in surface winds is also expected Thursday night into Friday with this system. Cooler, wet, and breezy conditions will persist into the weekend as this progressive, moist pattern stays locked in. Precipitation totals throughout this extended period may exceed 2" in some of the higher terrain, with 0.25 to 1" possible for lower elevations. Snowfall totals of over 2 feet are certainly possible for the mountains, though the oscillating snow levels will undoubtedly affect accumulations...causing the snow accumulation forecast to be much more uncertain. && .AVIATION...VFR, except in patchy valley fog/mist this morning, including at/around KBKE, KMYL, and KONO-KEUL. Surface winds: variable around 10 kt or less. Winds aloft at 10kft MSL: W-NW 20-35 kt, becoming W 10-20 kt this afternoon. KBOI...VFR, high clouds. Surface winds: southeast up to 7 kt, except light/variable in the afternoon. Sunday Outlook...Generally VFR with high clouds, except low stratus/patchy fog possible in sheltered valleys Sunday morning. Cloud decks lowering by late evening. Surface winds variable 5-15 kt. && .AIR STAGNATION...An upper level ridge will remain over the area through the weekend, resulting in stagnant conditions. Mixing heights will peak each afternoon at around 1,000 to 2,000 feet AGL through the weekend, and winds will generally remain less than 10 mph resulting in poor ventilation. An Air Stagnation Advisory will remain in effect through Sunday, and has been expanded to also include the West Central Mountains, Boise Mountains, and Camas Prairie. There is potential for stagnant conditions to persist into Monday before an active pattern brings increased mixing and winds, as well as precipitation, on Tuesday and Wednesday. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Air Stagnation Advisory until 5 AM MST Monday IDZ011>014-016-028-033. OR...Air Stagnation Advisory until 5 AM MST /4 AM PST/ Monday ORZ061>064. && $$ www.weather.gov/Boise Interact with us via social media: www.facebook.com/NWSBoise www.x.com/NWSBoise SHORT TERM...SA LONG TERM....SH AVIATION.....SH AIR STAGNATION...ST ####018005907#### FXUS65 KPUB 131022 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 322 AM MST Sat Dec 13 2025 .KEY MESSAGES... - Fog this morning far eastern plains then dry and breezy with elevated fire danger along portions of the I-25 corridor this afternoon. Low clouds and fog return tonight across the plains. - Warm and increasingly windy next week, with a chance for critical fire weather conditions Wednesday. - Snow showers possibly returning to the central mountains mid/late week. && .SHORT TERM /THROUGH TONIGHT/... Issued at 241 AM MST Sat Dec 13 2025 Fog has developed early this morning across portions of Kiowa and Prowers counties as southerly low level flow increases ahead of the deepening lee side surface trough. Flow aloft will shift more westerly which will help erode low clouds and fog eastward early this morning. Energy dropping through the northern plains this morning will send a cold front through southeast CO with low level winds shifting from an easterly upslope direction by this afternoon. Increasing winds will aide with mixing, in spite of some cold air advection aloft, allowing post frontal temperatures to still warm into the 50s to lower 60s across the plains. The warmest readings will be along the I-25 corridor where it will take the longest for the cooler air to work its way westward. Fire danger along the lower eastern slopes of the southeast mountains into portions of the I-25 corridor will be elevated today as breezy west winds ahead of the frontal passage combine with critically low humidity values near or below 15 percent. These conditions will be spotty and brief however, with humidity rising slowly as winds shift from a more easterly direction. Therefore no fire weather highlights look necessary. Elsewhere, the mountains and valleys will see temperatures fairly similar to a degree or two cooler than yesterday with dry conditions and breezy northwest winds. Easterly low level flow tonight will allow stratus and fog to redevelop across a larger portion of the southeast plains after midnight, particularly along and north of the Arkansas River/highway 50 corridor. KCOS may be right on the north west edge of this development as northerly winds off the Palmer may help to focus it just south of the city. Have introduced some fog and low clouds into the grids during the late night hours. Otherwise, it will remain dry across the mountains and valleys overnight with good radiational cooling allowing valley temperatures to dip down into the lower teens. Have cooled min temperatures several degrees for our typical cold pool valley locations. -KT && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 241 AM MST Sat Dec 13 2025 Patchy low clouds and fog will linger through the morning on Sunday, especially through the lower Arkansas Valley, where light easterly winds will persist. In fact, with a weak La Junta surface low in place for much of the day, easterly gradient will keep the Arkansas Valley cooler than surrounding areas, with max temps only in the upper 40s/lower 50s from Pueblo eastward. Elsewhere, temps will be slightly cooler than Sat numbers at most locations, though still some downslope enhanced readings in the 60s possible, especially over lee slopes west of I-25. Weak upper low drifts through the swrn U.S. upper ridge on Mon, but only impact on srn CO weather will be to keep winds rather light, as strong mid/upper nw flow is briefly disrupted by passing system. Starting Tue, flow across the wrn U.S. becomes more zonal, as upper ridge is suppressed off the California coast, bringing warmer temperatures and stronger winds to srn CO for much of the week. Wed looks like the windiest day, as upper jet will sag southward into nrn Colorado, and 700h flow across srn CO increases above 40 kts. Ahead of the jet's arrival, brief window for some mountain wave strong winds possible Wed morning, as weak reverse shear profile develops, before jet moves overhead and wave breaks down by afternoon. Still a lot to timing/location details to be worked out, but ensemble guidance suggests a near 50 percent chance of winds above 50 mph over much of the higher terrain along/west of I-25 Wed/Wed night. Fire danger will increase as well on Wed, as minimum relative humidity falls off toward 15 percent across the I-25 corridor and portions of the southeast plains during the day. Still breezy to windy Thu/Fri with jet overhead and strong mid-level flow, while snow showers return to the higher peaks of the central mountains as moisture and weak energy race eastward across the Continental Divide. Maxes may briefly cool Thu with a weak cold front, before deeper mixing and warmer air return on Fri. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 241 AM MST Sat Dec 13 2025 VFR conditions expected for the terminals today with breezy north to northwest winds at KCOS and KPUB this morning shifting to the east and southeast in the afternoon. Peak gusts up to 20 to 25 kts will be possible. Stratus and fog will develop tonight across the plains with best chances of IFR conditions or lower expected after 06z for both KCOS and KPUB. KCOS may see more low clouds than fog as winds shift around from a northerly downslope direction after 06z. Will keep lowest vis/cigs at KPUB based on consensus of short range high resolution models. KALS will see VFR conditions an persistent light and variable winds over the 24 hour period. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...KT LONG TERM...PETERSEN AVIATION...KT ####018004006#### FXUS64 KLZK 131022 AAA AFDLZK Area Forecast Discussion...UPDATED National Weather Service Little Rock AR 422 AM CST Sat Dec 13 2025 ...New AVIATION... .KEY MESSAGES... Issued at 149 AM CST Sat Dec 13 2025 -Very cold conditions move into the state for Sunday into Monday...with wind chills in the single digits and teens Sunday. Lows will be in the teens and 20s Sunday morning...and mainly in the teens for Monday morning -Warmer conditions return starting Tuesday into much of the upcoming week -Mainly dry conditions expected into Tuesday...but some rain chances return for Wednesday and especially Thursday of next week && .DISCUSSION... Issued at 149 AM CST Sat Dec 13 2025 The weak cold front that moved into the state on Fri afternoon has dropped south across SWRN sections of the state...resulting in generally cooler temps early this Sat morning for most areas with light NRLY winds and drier air filtering south. However...some moisture was beginning to lift north over the this front over SWRN sections...initially causing some fog...but has be more recently generating some low CIGs as the drier air undercuts this moisture. Further north...some low clouds and patchy fog were dropping south into NRN AR as colder air continues to drop south. Increased cloud cover and NRLY flow will keep temps cooler today than on Fri...with highs only in the 40s and 50s. A new surge of colder air will come late this afternoon and tonight as a new front drops south. This will bring much colder air to the state by Sun morning. Temps by just after sunrise Sun will have dropped into the teens across NRN sections...and 20s further south. A NRLY breeze will remain around this time...resulting in wind chill values in the single digits and teens for most areas. There may be some isolated spots in NRN AR see wind chill values dip to around or even just below zero Sun morning. Highs on Sun afternoon will remain well below normal in the 20s and 30s for most areas. Winds will relax by Sun night into Mon morning...allowing most areas to see temps drop into the teens for most areas as SFC high pressure settles across the state. There may also be some areas seen actual temps drop into the single digits Mon morning. SRLY flow will return by Tue...with warming conditions expected by the middle of the week. Temps will warm to around or even above normal by this timeframe. Some small rain chances may return to the forecast Wed into Thu as a weak upper wave passes overhead. However...better rain chances will be seen during the daytime hrs on Thu into Thu night as a new cold front surges SE through the region. && .AVIATION... (12Z TAFS) Issued at 421 AM CST Sat Dec 13 2025 Some patchy fog will remain possible this morning...as well as some MVFR CIGs as moisture lifts north. By later today and especially this afternoon/evening...NRLY winds will increase...allowing for colder air to surge south into the state. Some gusts may approach 20 kts at times. && .PRELIMINARY POINT TEMPS/POPS... Batesville AR 48 18 30 15 / 0 0 0 0 Camden AR 55 29 35 17 / 10 20 0 0 Harrison AR 48 14 29 17 / 0 0 0 0 Hot Springs AR 49 25 35 19 / 0 10 0 0 Little Rock AR 47 24 32 18 / 0 0 0 0 Monticello AR 56 28 33 19 / 10 20 0 0 Mount Ida AR 53 26 38 19 / 0 0 0 0 Mountain Home AR 46 15 29 15 / 0 0 0 0 Newport AR 45 18 29 15 / 0 0 0 0 Pine Bluff AR 50 25 32 18 / 10 10 0 0 Russellville AR 50 23 36 19 / 0 0 0 0 Searcy AR 47 21 30 14 / 0 0 0 0 Stuttgart AR 48 22 30 18 / 0 10 0 0 && .LZK WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...62 AVIATION...62