Area Forecast Discussion
Issued by NWS State College, PA
Issued by NWS State College, PA
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981 FXUS61 KCTP 111102 AFDCTP Area Forecast Discussion National Weather Service State College PA 702 AM EDT Sat May 11 2024 .SYNOPSIS... Upper level troughing will remain over Pennsylvania this weekend with a potent shortwave tracking over the state tonight into early Sunday. The upper trough will lift out early next week, then a cold front will likely push through Tuesday. A wave of low pressure is likely to track south of Pennsylvania next Wednesday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Upper level ridging in between shortwaves will result in fair weather the first half of today, with fog dissipating between 12Z-14Z. However, expect a return of showers this afternoon and evening associated with height falls ahead of a potent upper level shortwave diving across the Grt Lks. Strong large scale forcing, in combination with some minimal model cape, supports high POPs with a tsra possible in spots. Highest POPs should accompany the passage of the southerly low level jet and plume of best pwats. Convection-allowing models, which should perform well with this strongly forced system, indicate the most concentrated band of showers/tsra should arrive over the Alleghenies around 18Z, reach peak intensity over the Central Mtns at peak heating around 20Z, then push into the Susq Valley this evening. Although a brief, heavy downpour will occur in many locations, modest PWAT values indicate that rainfall should generally not be very heavy. Ensemble mean qpf of 0.2 to 0.4 inches represents the most likely rainfall by late this evening. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... The upper trough is progged to cut off and track along the PA/NY border tonight into Sunday morning. Low level instability associated with this feature should result in plenty of cloud cover and at least scattered showers lasting into Sunday afternoon, especially over the eastern half of the forecast area. Brightening skies and diminishing showers look likely by late Sunday afternoon, as the upper trough exits the state and surface surface ridging builds in from the west. Mixing down progged 850mb temps of around 4C translates to expected highs in the low to mid 60s over much of the forecast area, with upper 50s over the higher terrain of Eastern PA. The upper trough is progged to lift out early next week, with max temps rebounding +10-20F on Monday aided by a milder SW flow. A cold front trailing low pressure in eastern Canada is fcst to stall out over the lower Great Lakes Monday and could trigger a shower or t-storm over the NW mtns. Most of CPA should start the week rain-free. && .LONG TERM /TUESDAY THROUGH FRIDAY/... A wave of low pressure will approach from the Ohio Valley Tuesday before crossing the area Tuesday night. This system will be accompanied by a renewed chance of rain and perhaps some thunder. Lingering unsettled weather is possible into Wednesday, before a ridge build this system Wed night into Thurs. The overall upper level pattern heading into next weekend looks rather blocky - which is typical for this time of year - but also results in much lower confidence/predictability. Some data suggest a cut- off low pressure system could bring a slight risk of heavy rainfall on 5/18 per the latest CPC 8-14 day hazards outlook. && .AVIATION /11Z SATURDAY THROUGH WEDNESDAY/... Morning fog and low clouds are present across much of central PA this morning. The western airfields had clouds clear overnight, but ample low level moisture allowed for valley fog development. Central and eastern sites are still under low cloud cover, but some breaks in the clouds are expected after mid- morning. A wide range of conditions are present this morning given the variable cloud cover and patchy fog, areas experiencing dense fog are under LIFR conditions. Cigs and vsbys should improve to VFR areawide by midday on Saturday, before another round of rain showers pushes from west to east across the area Saturday aftn/eve with the approaching low pressure system from the west. This line of storms is expected to reach our western most airfields near 18Z today. Limited instability will allow for some thunder with these storms, but thunder is likely to decrease the further east the showers progress. Outlook... Sun...AM low cigs possible W Mtns. Sct afternoon showers/brief reductions possible. Mon...AM dry and mainly VFR. Showers return across the north by aftn. Tue...Showers/tstms and reductions developing. Wed...Showery weather and reductions continue. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Fitzgerald NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald LONG TERM...Steinbugl/Evanego AVIATION...Bowen