####018007618#### FXUS61 KPBZ 130805 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 305 AM EST Sat Dec 13 2025 .SYNOPSIS... Widespread snow returns this afternoon into early Sunday with the highest accumulation rates expected south of Pittsburgh; winter weather headlines in effect. Lake effect snow showers expected into early Monday. Very cold temperatures expected through Monday. Late week warm-up with temperatures well-above average. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... KEY MESSAGES: - Mainly dry tonight - Below normal temperatures expected to continue tonight ----------------------------------------------------------- As expected, winds weakening and becoming variable has brought about the end of snowfall across our northern counties. Skies are clear across much of the region with increasing subsidence. Clouds are expected to filter back in through the overnight hours ahead of our next system. Overnight lows are expected to remain in the low to mid 20s south and west of Pittsburgh and in the mid teens north and east. These temperatures are about 5 to 10 degrees below average during this period. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/... KEY MESSAGES: - Widespread snow Saturday afternoon into Sunday expected; winter headlines issued - Embedded snow bands within this system will likely prompt higher snowfall amounts - Potential for Cold Weather Advisory in the ridges - Lake effect snow expected Sunday afternoon into Sunday night ---------------------------------------------------------------- An Alberta clipper is forecast to move through the Ohio River Valley on Saturday afternoon, bringing widespread snowfall to the region. With strong confidence in sufficiently cold air aloft (850mb temps near -10 Celsius), all precipitation will fall as snow. The snow is expected to be dry/fluffy, with snow ratios ranging from 15:1 to 22:1 throughout the event. With deep moisture (extended above 300mb) and strengthening mid-level frontogenesis near I-70 late Saturday evening into Saturday night, embedded snow bands are likely to move through parts of the region. These bands will likely produce reduced visibility and snowfall rates between 0.5 to 1 inch per hour, creating very hazardous travel. The greatest potential for heavy snowfall rates is between 7pm Saturday to 1am Sunday.The Winter Storm Warning covers the best potential for these localized snow bands. However, counties currently under a Winter Weather Advisory may need to be upgraded to a Winter Storm Warning within the next 24 hours if high-resolution models show snow bands shifting slightly farther north. As drier air moves in aloft from the west with the passing trough axis, the likelihood of widespread snow will diminish late Sunday morning. Attention will then shift to lake-effect snow bands as boundary layer winds turn northwesterly. Counties near I-80 will continue to hold the Winter Weather Advisory into Sunday night. However, if a prolong significant snow band develops, a county or two may need to be upgraded to a Lake Effect Warning in the next 48 hours. In addition to the snow, very cold temperatures are expected during this period. Wind chill values late Sunday will likely range from 0 to 10 degrees, with readings below zero along the ridges. A Cold Weather Advisory will likely be needed for at least the West Virginia ridges in the next 48 hours. && .LONG TERM /MONDAY THROUGH FRIDAY/... KEY MESSAGES: - Much colder with snow chances into Monday morning - Warmer with rain returning for the second half of the week ------------------------------------------------------------------- Monday will continue highly anomalous cold with temperatures around 20 degrees below average. Wind chills in the early morning may be as low as -5F to -10F for the higher terrain of PA and WV, and single digits for the lowlands. Into the day, some warming will bring wind chills into the low 10s and upper single digits for most. A weak clipper system may pass on Monday, with a 50% to 70% chance of snow accumulations northeast of Pittsburgh,m but only a 10% to 20% chance of >1". Through Thursday, a pattern chance will ensue, with ridging. Temperatures will trend below normal Tuesday, near normal Wednesday, then slightly above normal by Thursday. The only uncertainty in the forecast will largely be the degree a ridging and timing or presence of shortwaves in quasi-zonal flow. Slightly higher heights could be a degree or two higher than the ensemble mean, where lower could be a degree to two lower. In progressive flow, weak shortwaves remain possible, but the best chances or rain come Thursday ona wave passage.Saturday Thereafter, forecast confidence decreases, though most guidance trends warmer than average. The spread between the 10th percentile and 90th percentile temperatures is almost 10 degrees, with the cool side being near-normal, and the warm side being ~10 degrees above average. This pattern will also carry higher chances of rain and above average precipitation (December 20th-23rd). && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... KEY MESSAGES: - MVFR cigs this morning - Widespread snow with deterioration to LIFR this afternoon/evening ------------------------------------------------------------ MVFR stratocu has spread across the region early this morning ahead of an approaching front progged to cross the region late this morning/and through the afternoon. Post-frontal cigs will drop to IFR and LIFR as more widespread snow arrives early this afternoon. Visibilities are likely to drop to IFR or lower in snow by mid to late afternoon, mainly south of I-80, and continuing into the evening hours. Peak snowfall rates at KPIT and terminals to the south look to be between 0.4" and 0.6" per hour from mid- afternoon until mid- evening. Additionally, gusty W-WSW wind will increase with gusts around 20kts behind the front. Outlook... LIFR is expected to continue overnight in widespread snow as the shortwave completes its passage. Restrictions and scattered snow showers are then expected to continue through Monday morning in cold NW flow off of the Great Lakes. There will also likely be a lake effect snow band, with the highest impacts at FKL. General VFR should return by late Monday through Wednesday as high pressure briefly builds in. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Winter Weather Advisory from 1 PM this afternoon to 1 PM EST Sunday for PAZ013-014-020>022-077-078. Winter Storm Warning from 1 PM this afternoon to 1 PM EST Sunday for PAZ029-031-073>076. Winter Weather Advisory from 1 PM this afternoon to 7 AM EST Monday for PAZ007>009-015-016. OH...Winter Weather Advisory from 1 PM this afternoon to 1 PM EST Sunday for OHZ039>041-048>050-057-058. Winter Storm Warning from 1 PM this afternoon to 1 PM EST Sunday for OHZ059-068-069. WV...Winter Weather Advisory from 1 PM this afternoon to 1 PM EST Sunday for WVZ001-002. Winter Storm Warning from 1 PM this afternoon to 1 PM EST Sunday for WVZ003-004-012-021-509>514. && $$ SYNOPSIS...Hefferan/Lupo NEAR TERM...Hefferan/AK SHORT TERM...Hefferan LONG TERM...Milcarek AVIATION...88 ####018002784#### FXUS65 KPIH 130805 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 105 AM MST Sat Dec 13 2025 .KEY MESSAGES... - Above average temperatures continue into next week - Wet and windy conditions return starting Monday && .SHORT TERM /THROUGH TONIGHT/... Issued at 104 AM MST Sat Dec 13 2025 High pressure should produce mostly sunny skies and lighter winds. Continued mild weather is expected with record or near record highs at many sites. The most vulnerable sites include IDA whose record is 46 set in 2014 and PIH whose record is 53 in 1969. LLJ and SNT could get close as well. Challis's record is 53 set in 1921 and Stanley is 50 in 1924. Burley is the only site that is safe with a record of 65 set in 1929. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 1144 AM MST Fri Dec 12 2025 Mild northwest flow pattern continues for the foreseeable future. Valley daytime highs remain well above normal for this time of year, and overnight lows are close to the normal highs. We do see the ridge begin to shift east Monday with onset of precipitation across the region Monday night into Tuesday. Clusters this morning are similar on timing of the breakdown and arrival of precipitation and wind into East Idaho for midweek. Precipitation appears focused for the higher elevations of East Idaho, particularly the western edges of the central mountain zones and along the Wyoming border. Snow levels remain high as the system arrives, but do weaken through the day Wednesday with progression of a cold front through the region. Temperatures do lower Tuesday into Wednesday, but remain warm at lower levels so any precipitation that does fall through the Snake Plain will likely remain rain, at least until Wednesday night as overnight lows approach freezing. Unsettled and mild conditions continue through the end of the week and forecast period with another feature bringing mainly higher elevation snow. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1032 PM MST Fri Dec 12 2025 High pressure will keep conditions unlimited for VSBY and CIG. Lower clouds that were over KDIJ not expected to return. Main forecast changes in each TAF were for wind shifts, but even then only KDIJ is expected to have wind approaching 15KT. Building ridge has hopefully put to rest the breezy valley conditions at KPIH and KIDA. 25KT wind at around 750mb above KIDA is expected to decrease later tonight and not return Sat afternoon. KPIH wind is in a similar trend below 800mb. && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...13 LONG TERM...DMH AVIATION...Messick ####018006237#### FXUS63 KAPX 130808 AFDAPX Area Forecast Discussion National Weather Service Gaylord MI 308 AM EST Sat Dec 13 2025 .KEY MESSAGES... -Ongoing lake effect snow will continue to impact the typical snowbelts of northern Michigan through Sunday morning. -Very cold temperatures and wind chills expected through tonight with apparent temps well below zero. -Mild weather returns later next week with highs above freezing Wednesday and Thursday. && .SHORT TERM /THROUGH TONIGHT/... Issued at 307 AM EST Sat Dec 13 2025 Pattern Synopsis...Longwave midlevel troughing with a decent jet core (150-170+ kts) continues to stretch across the northern half of North America. cP and cA air from the north will plummet surface temperatures the next few days across the Great Lakes region. Open water and warm lake temperatures will continue lake effect snow through the short term, especially tonight as midlevel embedded shortwave troughing digs across the CWA. Forecast Details... Today...Post cold frontal condtions are the main focus on today's forecast as cold air advection draws cA into the region with gusts in the mid 20s and highs in the low to mid teens. Even with dry atmospheric midlevels today, ongoing lake effect snow supported with lake aggregate troughing will provide enough instability to accumulate several inches for localized parts of the CWA. WNW directional winds will favor classic snowbelts of northern Michigan, mainly west of I-75. All counties currently under advisories can only expect only a general 2-4" for most locations through 00Z tonight due to daytime heating over land creating a unstable environment and turning LES bands more cellular. However; better fetch, orographic lift, and stronger low level directional shear over the classic "big five" of northern lower (Charlevoix, Kalkaska, Otsego, Crawford, and Antrim) will see localized higher totals of 6- 8"+. Northern parts of the UP will receive the highest QPF across the CWA as favorable fetch across lake superior delivers higher snowfall totals. Expect widespread amounts of 1-3" across the majority of eastern upper while areas near and north of M-28 has medium to high probabilities (40-70%) of 4-8" and localized amounts of over 10" near and north of Sault Ste. Marie Tonight...Winds will decouple right after sunset for a few hours then start to veer, shifting snowbands and highest snow totals slightly southwest compared to today. By 12z Sunday, radar will appear to have returned to classic NNW milti-banded LES. Widespread additional amounts of 1-3" of 18:1 snowfall can be expected across most of the snowbelts while localized areas of Antrim and Kalkaska county of 2-4"+ by Sunday morning. Most widespread noticeable/impactful weather overnight will be the continued cold temperatures as overnight lows in the single digits. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Issued at 307 AM EST Sat Dec 13 2025 Sunday and Monday...Previously mentioned shortwave troughing will be positioned over eastern Lake Huron Sunday. Persistent breezy NW winds will continue the typical par-of-the-course lake effect snow. Dry low to mid level atmospheric conditions and weaker low level winds will lead to lower QPF totals. Most accumulations of roughly an inch or less is expected for the typical snow belts of northern lower and eastern upper. Another embedded shortwave develops lee of the Canadian Rockies and progresses to southern Ontario this Monday. Highest synoptic-driven snowfall favors the northern parts of the CWA with low to medium probabilities (30-50%) of a general 2-4" near and north of the bridge. Still too early to give a more definitive forecast, but another widespread round of snow with a quick shot of LES is expected this Monday through Monday night. Tuesday and Wednesday...Longwave troughing pattern over the northern CONUS and Canada will begin to progress northward, raising midlevel heights across the Great Lakes region and creating more of a zonal flow pattern. This will support high pressure to build from the south and return some overdue mild and quiet weather. At the surface, little to no precip is expected while temperatures build above freezing with highs in the upper 30s to low 40s. Thursday and Friday Outlook...Long range ensemble guidance depicts another trough digging across the midwest around the Thursday timeframe. Current trends show a lack of southerly moisture advection, hinting at low amounts of QPF. Most of the impacts and potential concern remains from warm air advection reintroducing multiple precipitation types. Most likely outcome will be rainfall Thursday then transitioning to light snowfall as soon as post frontal CAA moves into the CWA. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 1141 PM EST Fri Dec 12 2025 Lake effect snow will continue to organize through early this morning, with the primary target area centering between taf locations into the northwest lower Michigan snow belts through today. Still expecting to see some lighter snow showers and areas of lower cigs at the taf locations, but thinking vast majority of this time will remain MVFR to lower end VFR. West winds will remain gusty (up and over 25 knots at times), producing some blowing and drifting snow as well. Winds veer northwest this evening, focusing bands of snow across the western taf locations...likely producing periods of IFR conditions. && .APX WATCHES/WARNINGS/ADVISORIES... MI...Winter Weather Advisory until 7 AM EST Sunday for MIZ016-017- 020>022-025>028-031-032-099. Winter Storm Warning until midnight EST tonight for MIZ086-087. MARINE...Small Craft Advisory until 1 PM EST Sunday for LHZ345>349. Small Craft Advisory until 11 AM EST Sunday for LMZ323-341-342- 344>346. Small Craft Advisory until 7 PM EST this evening for LSZ321- 322. && $$ SHORT TERM...SJC LONG TERM...SJC AVIATION...MSB