Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/18/21

Area Forecast Discussion
National Weather Service State College PA
1057 PM EST Fri Dec 17 2021 .SYNOPSIS... A storm system will bring a rainy start to the weekend, as it tracks directly across Pennsylvania. Temperatures will likely be cold enough over the northern Mountains for a period of snow, sleet and freezing rain with a light accumulation late tonight into Saturday morning. High pressure will build back in for Sunday and Monday, leading to dry and seasonably chilly weather which will last for the better part of next week. && .NEAR TERM /UNTIL 8 AM SATURDAY MORNING/... All is on track. Rain (not measured yet) is falling in the SW third of the area. Temp down to 36F in Somerset (K2G9) and dewpoint up to 30F from near 10F earlier. So...there could be some non-rain hitting the highest hill tops. No, it`s not snowing in Bedford (KHMZ) per webcam. The AWOS there just tends to report --RA/DZ as snow at times. Prev... Clouds lowering over the SW, and radar returns aloft are getting closer to the CWA. However, dewpoints in the teens in the SW with a 9F Td at KAOO right now will make it difficult for anything to reach the surface in the next 3 hrs. RAP soundings show a slow moistening at the sfc with the temp profile still well above freezing thru the night. However, the higher hill tops may cool down to freezing with rain the dominant p-type later tonight. Temps cooling off on the expected schedule over most of the area. Only minor tweaks to grids. Wx grids are a complex mix of everything across the N later tonight. Prev... The leading edge of precip will spread NE across the SW half of PA by about 06-08Z and likely start across the Laurel Highlands shortly before midnight. Deep layer of dry and chilly air should wet bulb down to the 28-32F range very late tonight through Sat morning across northern PA and to a lesser degree across the Central Mtns. Timing of the cloud cover is not favorable for the ground to radiate a significant amount tonight across the north to support widespread freezing rain. However, the elevated layer of sub- freezing wet bulb temps will readily support at least a several hour period of wet snow and/or sleet over the higher terrain between I-80 and the PA/NY border. We collaborated with WFOs BUF, BGM, CLE and PBZ to issue a Winter Weather Advisory for the 09Z-18Z Sat period for the Northern Mtns of PA. Minimal travel impacts are expected in most places, thanks to the warm ground from the recent record breaking temps and aforementioned lack of ideal radiational cooling conditions to chill the ground tonight. && .SHORT TERM /8 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Similar conditions (as noted in the paragraph immediately above) will continue through Sat morning with a good coating to one inch of sleet/snow likely across the northern mtns, and even a ground whitening of sleet possible throughout Central PA as 925 mb wet bulbs hover in the -1 to -2C range until around 17Z. Again, the main system of consequence this period will be a southern stream origin disturbance, with the surface reflection expected to track from the Ohio Valley later tonight, across PA on Saturday, then off the NJ coast Saturday night and early Sunday. It does still appear from model solutions that this system will tend to deepen as it passes on Saturday, with decent jet dynamics at play. The best forced ascent looks to develop from the Alleghenies up over the northern tier, where liquid equivalent precipitation amounts will mostly range from 0.75-1.25" later tonight and Saturday. This is good news for parts of the Laurel/Allegheny Highlands, where it has been fairly dry the last several weeks. Rain should begin to shift eastward and out of the region later Saturday and Saturday evening. As the aforementioned storm system departs to the east, it will begin to pull down enough colder air so that rain tapers off to snow showers over the Alleghenies and PA`s northern tier counties Saturday evening. However, the overall lake response should be muted, with rapid dry advection and low capping inversion heights foreseen. We`ll close out the weekend Sunday with increasing sunshine, but also with brisk, chilly conditions. Highs Sunday afternoon will range from near 30 in the northern mountains, to the lower 40s in the Lower Susquehanna Valley. && .LONG TERM /SUNDAY THROUGH FRIDAY/... High pressure builds over the area early in this period, bringing fair and seasonably cool conditions. Zonal flow aloft persists through midweek, and leads to a stalling cold front extending from the central GLAKS to southern New England, keeping most inclement weather to our north. Extended models have diverged substantially on phasing of the northern and southern stream over the latter half of next week, and latest guidance continues to reflect this, leaving the end of the week and Christmas Day highly uncertain, given the spread of solutions. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... VFR conditions will transition to MVFR overnight (05z to 09z) across the Laurels and northern mountains, along with the arrival of light rain, mixed with sleet and FZRA in the northern tier. Elsewhere, expect a gradually thickening cirrostratus deck, followed by cigs lowering to around 6 kft with light precip possible by sunrise for central and east central PA. Conditions will gradually worsen on Saturday with widespread IFR cigs expected by afternoon, and LIFR possible for BFD and JST. Precip should switch to plain rain for all, with vsby restricted in -RA and BR. Some LLWS is expected across mainly the western half of the area as swrly flow increases to 40 kts at 2kft, atop sfc winds that are southeasterly and less than 10 kts. Outlook... Sat night-Sun...Lingering reductions N/W, with scattered -SHSN. Becoming VFR elsewhere. Mon-Tue...Generally VFR. && .CLIMATE... Harrisburg set their daily max temp today/Friday (around 1AM). && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 4 AM to 1 PM EST Saturday for PAZ004>006-010>012-037-041-042. && $$ SYNOPSIS...Jurewicz/Lambert NEAR TERM...Jurewicz/Lambert/Dangelo SHORT TERM...Jurewicz/Lambert LONG TERM...DeVoir/Evanego AVIATION...Lambert/Colbert CLIMATE...
Area Forecast Discussion
National Weather Service Lincoln IL
721 PM CST Fri Dec 17 2021 .SYNOPSIS... Issued at 721 PM CST Fri Dec 17 2021 Periods of rain will continue overnight into early Saturday across central and southeast Illinois, with the steadiest rain south of I-70. A mixture of sleet and rain is possible late this evening north and west of Peoria, but this should change over to all rain after midnight. After the rain moves out, dry weather is expected for the remainder of the weekend. && .UPDATE... Issued at 721 PM CST Fri Dec 17 2021 Initial area of rain continues to be most widespread south of I-70, with regional radar mosaics showing an increase in shower activity further north from central Missouri over to near Danville. This northward expansion is expected to continue this evening. Some of the high-res models suggest a rain/sleet mix in the far northwest CWA, with HRRR soundings from Galesburg showing a warm layer of 1-2C just above 800 mb. This layer was sampled by our evening sounding, though warmer down here around 5C. A trend toward all rain is indicated after midnight in that area. Temperatures over most of the area shouldn`t change much overnight, though the southeast CWA is expected to climb into the 40s as the front gets close to Lawrenceville. && .SHORT TERM...(This evening through Saturday) ISSUED AT 252 PM CST Fri Dec 17 2021 A frontal system will continue to spread rain across eastern and southeastern Illinois early this evening, but the rain will spread north and northwestward during the evening hours and then continue overnight. Will be keeping the highest pops east of the Illinois river with chance pops around Galesburg where HiRes models keep agree that the threat there will be limited. The rain should end during the morning hours Saturday, but mostly cloudy skies will remain through the afternoon hours. Cloud cover and precip will hold temps and only expecting slowly falling or nearly steady temperatures, reaching the lower 30s in the north to the upper 30s in the southeast. Sat afternoon highs will return to the upper 30s in the north to the mid 40s in the southeast. && .LONG TERM...(Saturday night through Friday) ISSUED AT 252 PM CST Fri Dec 17 2021 Once the front moves east of the area, high pressure will build into the region with dry weather. Even though another front is expected to move through the state around mid week, it should come through dry. Expect dry weather through the week with maybe a chance of precip toward the weekend. Temps through the period will range from the lower 30s to the upper 40s, with Wednesday being the coolest with mid 30s in the north to around 40 in the southeast. The warmest days will be Thur and Fri when afternoon highs reach back into the middle to upper 40s...a return to above normal temps. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 519 PM CST Fri Dec 17 2021 Ceilings below 3000 feet have reached KSPI-KCMI early this evening and will continue to push over the next few hours. Will continue to see deteriorating conditions over central Illinois through the evening, with IFR conditions likely from KSPI-KCMI before 06Z. These lower ceilings likely will reach KPIA/KBMI by 09Z. A gradual improvement is likely from west to east Saturday midday and afternoon. Rain showers are expected to spread across central Illinois this evening. Some of the guidance hints at potential for some sleet near KPIA later this evening, and will monitor that for any needed amendments. Threat should lift north of there by 06Z. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Geelhart SYNOPSIS...Geelhart SHORT TERM...Auten LONG TERM...Auten AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Sacramento CA
241 PM PST Fri Dec 17 2021 .SYNOPSIS... Dry weather into early next week. Cold nights with Valley fog and frost possible into early next week. Rain and snow chances return next week, with gusty winds at times. Mountain travel will likely be impacted. && .DISCUSSION... Visible satellite imagery depicts mostly clear skies across our region this afternoon. Although, there are some lingering low clouds still present in the San Joaquin Valley. Cool temperatures are also being observed in areas in the Valley that saw low clouds and fog today, with the Sacramento metro region running about 5 to 10 degrees cooler than this time 24 hours ago. Elsewhere, areas under sunny skies are seeing temperatures 5 to 15 degrees warmer than yesterday at this time. Ensemble guidance is in good acquirement high pressure over California will keep our region dry through the weekend. The cool airmass in place in combination with light winds and mostly clear skies this afternoon will lead to widespread near to below freezing temperatures tonight in the Valley. Frost is likely to develop as well as low clouds and fog overnight tonight into tomorrow morning and will be possible in the overnight and morning hours each day into early next week. HREF and HRRR guidance are in agreement low clouds and valley fog will be more widespread tomorrow morning than what was observed today with low clouds potentially lingering for much of the day over the Sacramento region and locations southward in the Valley. Mountain areas will see a cool start to the day with partly cloudy skies. Early next week a change in the weather pattern is anticipated with wet weather returning to the region. ensemble guidance is in agreement a low pressure system will likely deepen off the West Coast. This feature is forecast to bring periods of valley rain and mountain snow, however timing is still uncertain as the low may stall off the west coast early next week. Current guidance has precipitation chances gradually spreading south and eastward as early as Monday. Snow levels could start below 3000 4500 feet. Snow could begin to bring travel problems to the northern mountains starting Monday, though higher potential for this will come later. && .EXTENDED DISCUSSION (Tuesday THROUGH Friday)... Ensemble guidance remains in agreement that longwave troughing will develop off of the West Coast next week, producing multiple rounds of widespread precipitation for Northern California into next weekend. However, timing of when precipitation will begin pushing into California is slowing down as the ensembles depict the trough deepening off of the coast. Precipitation onset is now slated for later Monday into Tuesday. Uncertainty remains in timing and amounts as cluster analysis suggests some differences regarding the progression and position of the trough. Overall, we are forecasting around one to three inches of rain for the Valley and multiple feet of snow over the mountains over a multi-day period, which will likely cause holiday travel disruptions. Periods of gusty winds are also possible with individual weather systems, and temperatures will remain relatively mild. -HEC && .AVIATION... MVFR/IFR/LIFR conditions due to BF/FG are forecast to return across the Valley after 09-12Z Saturday and may remain through most of the day Saturday for areas near and south of the Sacramento area. Otherwise, VFR conditions expected next 24 hours with winds generally below 10 kts. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$