Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 150741 AFDCTP Area Forecast Discussion National Weather Service State College PA 241 AM EST Thu Feb 15 2018 .SYNOPSIS... Temperatures will be on the rise into the second half of the week along and there will be several opportunities for rain. A cold front will pass through on Friday bringing colder weather for the weekend. && .NEAR TERM /UNTIL 10 AM THIS MORNING/... Numerous showers around all over the area except the far nrn counties. Temps well above freezing, and JST and AOO are in the 50s with 100pct RH already. Fog not terrible yet, but places with most snow on ground are worst. The inversion over the ern and West Branch valleys keeps it coolest there. Seems like there is a little elevated instability despite the low crud, but it is very limited. Kept high POPs until close to sunrise, and fog mentions into the mid- morning. Not much improvement in sky conditions thru the day, but some breaks may appear in the far S in the morning. Expect temps and dewpoints to stay steady or rise very slightly thru the morning. && .SHORT TERM /10 AM THIS MORNING THROUGH 6 PM FRIDAY/... Any lingering rain showers Thursday morning will move east and provide us with a short-lived break in the precipitation. As the next wave of precipitation moves toward the region ahead of a cold front/low pressure system, south winds will help temperatures approach the l60s south of rte 22. Not much clearing is expected, but the far SC & SE counties have some potential. If they do break out for a longer time, it could be into the m60s due to the 8H temps about +10C. 65-70KT LLJet pushes into the area from the OH valley tonight, and deep moisture plume yields a high precip efficiency. Add this to the upslope/orographic effects of the Apps, and we will see some heavy rain tonight and early Fri. QPF looks higher with the latest runs than what we have going. Will re-assess the extent of the FFA later this shift Prev... Model guidance continues to support the potential for heavy rainfall Thursday night into Friday over southwest PA. GEFS PWAT values reach +3-4SD above normal and mean QPF m-climate percentiles are nearly maxed out at 6, 12 and 24 hour intervals. The anomalous moisture/heavy rain combined with wet antecedent conditions, enhanced runoff (due to wet & cold ground surface & no vegetation) and above normal streamflows will all contribute to localized and river flooding potential. Issued flood watch for Somerset County in collaboration with PBZ. The mild weather will be erased (briefly) as a cold front sends temperatures falling on Friday. There will likely be a transition zone from rain to snow across the northwest 1/2 of the area with a slushy accumulation possible over the higher terrain as the colder air catches up with the back edge of the frontal precip. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Confidence continues to increase in the `sneaky` winter weather threat Saturday into Saturday night. There is much better model agreement in a period of snow spreading over much of CPA with the potential for widespread light to moderate accumulation by Sunday morning. Expect more information on this as the event including potential amounts as it moves inside the 72-hour window. The mild pattern will resume next week with rounds of rain targeting the northwest 1/2 of the area. && .AVIATION /07Z THURSDAY THROUGH MONDAY/...
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Surface analysis at 06Z places a slow moving warm front across southwest Pa, running just north of KJST/KAOO and west of KHGR. Upslope flow into the Laurel Highlands is likely to yield predominantly IFR cigs at KJST through dawn, while downsloping southwest flow yields predominantly MVFR cigs at KAOO. The rest of central Pa will remain north of the front early this morning, with at least tempo IFR cigs/vsbys. The worst conditions are likely to be at KBFD, where moist upslope flow is likely to result in predominantly LIFR cigs/vsbys through mid morning. An examination of model soundings indicate northern Pa will experience marginal LLWS conditions early this morning, which should abate by around 12Z, as the core of stronger winds aloft shift north of the state. Improving conditions across the entire area appear very likely between 12Z-18Z, as the surface warm front lifts northward. Model soundings and SREF prob charts support a return to VFR conditions by afternoon across much of central Pa. while a moist southwest flow ascending the Allegheny Mountains is likely to result in lingering MVFR cigs at KBFD/KJST. An area of low pressure approaching from the midwest will track across Pennsylvania tonight, resulting in rain and deteriorating cigs/vsbys by this evening. Outlook... Fri...AM low cigs/showers, mainly W Mtns, then becoming breezy. Sat...PM snow/mixed precip possible. Sun...Early AM fog/low cigs possible. Mon...Rain/low cigs possible, especially NW Mtns.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... Flood Watch from this evening through Friday evening for PAZ033. && $$ SYNOPSIS...Dangelo NEAR TERM...Dangelo SHORT TERM...Dangelo LONG TERM...Steinbugl AVIATION...Fitzgerald

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