Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 211541 AFDCTP Area Forecast Discussion National Weather Service State College PA 1041 AM EST Sun Jan 21 2018 .SYNOPSIS...
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A warm frontal boundary drifting slowly north across the region will bring some occasional light rain or drizzle into early Monday. A potent area of low pressure moving northeast across the Great Lakes will push a trailing cold front through Pennsylvania on Tuesday. Temperatures will rise above normal today and stay there through early Tuesday, before falling back to near or slightly below normal Wednesday and Thursday. A rebound in temperatures to above normal levels will occur again for next weekend.
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&& .NEAR TERM /UNTIL 7 PM THIS EVENING/...
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Clouds cover the area and temps only inching up. All is well. Prev... The risk of ice jam flooding will continue over the weekend and into early next week. See the hydro section for more details. An extensive shield of strato cu has advected east across practically the entire CWA over the past several hours. as this cloud deck slowly lowers and thickens up today, we`ll see some areas of light rain or drizzle develop (mainly across the northwest half of the state). Little or no chance for measurable precip exists near and to the SE of the I-81 corridor. Winds will be light for the most part and from the southwest. Temps that are currently about 5-8 deg F above normal across the Susq Valley, and nearly 20 deg F above normal across the Central and NW Mtns will warm into the 40s in all locations today, with a few spots in southern PA reaching the 50 deg mark.
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&& .SHORT TERM /7 PM THIS EVENING THROUGH 6 PM MONDAY/... The start of warm advection Sunday night and Monday ahead of a strengthening Mississippi Valley/Great Lakes cyclone will impinge on a retreating thermal gradient between I-80 and I-90. Forecast soundings indicate moisture will be rather shallow initially with areas of light rain confined mainly to the western and northern parts of the area. Elsewhere expect low clouds to develop with pockets of drizzle/mist and fog. As the cyclone approaches, Monday will see the light showers retreat to the north with the warm front (thermal boundary). && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Another January thaw will bring a period of relatively mild weather to Central PA through early next week. Temperatures are not expected to be as warm as the previous thaw (late last week), but departures should reach +10 to +15 degrees above average for mid to late January, peaking Monday in the NW and Mon into Tues in the SE. The progressive pattern will keep the cool down during the middle/late part of next week rather brief before temperatures moderate/trend warmer into next weekend. A weak secondary low may form in the lee of the Appalachians and support a period of enhanced rainfall over the eastern 1/2 of PA Tuesday morning. At this time, the total rainfall forecast for early next week does not appear to be as heavy as Jan. 11-12. The most likely period for widespread rain is Monday night into early Tuesday along/ahead of south-southwesterly LLJ axis and cold/occluded front. Winds look rather blustery from later Tuesday into Wednesday on the backside of the low pressure system as colder air filters back in. Snow showers are likely downwind of Lake Erie into Wed night. Dry wx with moderating temperatures Thu-Fri under high pressure. Some showers may sneak into the NW Sat as weaker low pressure system lifts across the Great Lakes, with better chances for rain with another low on Sunday. && .AVIATION /16Z SUNDAY THROUGH THURSDAY/... Low stratu cu continues to move over the region this morning. MVFR is over all central and eastern TAF sites, with IFR and lower at BFD and JST. Expect these conditions to continue through the morning. Latest HRRR continues to show chances for light rain/drizzle will increase as the morning continues for the western TAF sites, with AOO, IPT and UNV having IFR possible tonight into tomorrow morning. Expect restrictions to continue into tomorrow morning with improvements from the south to the north by 18Z Monday afternoon. Outlook... Sun PM...SCT SHRA - mainly in the north. Otherwise MVFR S and IFR N. Mon...Reduced flight categories with rain showers associated with an approaching cold front - mainly N. Improvement expected from S-N thru the day. Tue...VFR w/SCT MVFR in SHRA. Tues PM-Wed...IFR SHSN NW. MVFR/VFR SE. Thurs...No sig wx. && .HYDROLOGY...
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Main concern is watching water levels rise on Susq downstream of Harrisburg. Marietta gage /MRTP1/ being only about 2.5 FT below FS of 49 FT but is now showing a slow but steady fall. Ice effects are still possible, though. The Flood Watch for this area extends into Monday afternoon. With milder temperatures there is potential for ice movement, as well as slow ice deterioration/thinning with time. All areas near rivers and streams that have significant ice buildup should monitor water levels closely for the next several days.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... Flood Watch through Monday afternoon for PAZ065-066. && $$ SYNOPSIS...Lambert NEAR TERM...Dangelo/Lambert SHORT TERM...Dangelo/Lambert LONG TERM...Lambert/RXR AVIATION...Dangelo/Ceru HYDROLOGY...

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