Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 140344 AFDCTP Area Forecast Discussion National Weather Service State College PA 1044 PM EST Tue Feb 13 2018 .SYNOPSIS... High pressure will drift east and off the New England coast tonight. An increasingly moist southerly flow will bring unsettled conditions from mid week until a cold front passes through Friday ushering drier conditions for the weekend. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Near term forecast problem remains centered on the potential for some light icing overnight into early Wednesday morning. The favorable right entrance region of an upper jet streak and increasing warm advection/isentropic lift will bring a small chance of some very light rain/drizzle/freezing drizzle. The latest radar shows some light disorganized showers moving through WRN PA. With surface temps hanging close to freezing, we will issue an SPS to cover potential for icy pockets. If it becomes apparent precip is actually hitting the ground as it moves into the CWA, we may need a short lived advisory. From earlier... The HRRR shows a small area of very light precip streak across the area from I-80 northward after midnight. The SPC HREF keeps the area dry so the confidence in actually seeing precip is pretty low. Covered the low threat and spotty nature of any light icing in the Hazardous Weather Outlook for now. If confidence increases that some light precipitation will actually develop, we will have to issue a short lived headline for slippery travel. Min temps overnight will be in the 25-30 deg range. The wind will be mainly east to southeast at 5-10 mph.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... Better chances for rain arrive late in the day or early evening Wed with upper level diffluence increasing and mid-lvl winds into the 50s out of the West. Max temps Wednesday will be about 10F warmer than Tuesday and it will be mild enough for plain rain everywhere by then. Rainfall amounts will stay rather light and generally several hundredths to around 0.10 of an inch, as the forcing continues to look disorganized. Temps will be very mild with well above normal mins and maxes Wed night and Thursday. So, despite the cloudiness on Thursday, the temps should rise into the 50s and some 60s across the south. 70F might not be all that far south of the Mason-Dixon line. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... Temperatures will be on the rise for the second half of the week, along with the opportunity for rain. The springlike surge of mild air should send temperatures 20+ degrees above average Thursday and Thursday night. The mild weather will be erased (briefly) as a cold front sends temperatures falling on Friday before readings bottom near normals levels for mid February on Saturday. High temperatures on Saturday will be 20 to 30 degrees colder than Thursday (48-hour change). As high pressure migrates off the Eastern Seaboard, broad ascent in the warm air advection pattern will allow for clouds and periods of light rain, drizzle and fog to develop Wednesday night and Thursday. Model guidance continues to advertise the potential for enhanced rainfall Thursday night into Friday in response to strengthening southwesterly low level jet along a tightening baroclinic zone/frontal boundary pushing southeast from the Midwest/OH Valley. Ensemble PWAT values reach +3SD above normal. The anomalous moisture combined with cold ground/enhanced runoff could lead to heavy rainfall (1-2+ inches) and flooding potential. At this time, the greatest risk area is focused from southern OH into northern WV and southwest PA including the Laurel Highlands. The placement of the high QPF axis is still uncertain and the Day 3 WPC excessive rain risk area splits the difference between the southern GFS and northern ECMWF precip axis. An ECMWF/CMC/GEFS consensus brings the possibility of some wintry weather back into the picture later Saturday into Saturday night. Will need to see if this recent model trends hold and the GFS comes on-board before increasing confidence and sensible wx elements. But it is something to definitely monitor in the coming days. Sunday looks dry for now with precipitation returning into early next week. After a short break, the mild trend should resume next week with above average temperatures a good bet. && .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/... MVFR has spread through the western TAF sites as southwesterly upper level flow couples with moist southerly flow at the surface. Expect this flow to continue as the night continues. Cigs and vsbys will continue to degrade as the night continues and through the daybreak. There is a low probability for some patchy little mixed precipitation (mainly light freezing rain or freezing drizzle) late. For now...left this out of the TAF fcsts... given how dry the low levels are and anticipated spottiness with little organized upper dynamics to generate appreciable swaths of precipitation. Outlook... Wed-Thu...Low cigs/light rain possible, mainly N Mtns (KBFD). Fri...Windy and turning much colder. AM rain, changing to periods of light snow or snow showers mainly across the Western Mtns. Cig reductions likely early, and continuing during the afternoon across the NW mtns and Laurel Highlands. Sat...No sig wx expected. Sat night and Sunday...Chance of snow and lowering Cigs/Vsbys to MVFR with areas of IFR. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte NEAR TERM...La Corte SHORT TERM...Lambert LONG TERM...Steinbugl AVIATION...Lambert/Ceru

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