Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
113 PM EDT Monday Apr 27 2015
An upper disturbance will move south across the region today and
early tonight. Mainly dry conditions with moderating temperatures
will occur Tuesday and Wednesday. Late this week a slow moving
upper low will bring a return of cool and showery conditions.
Near term /through tonight/...
A sprawling upper low over the Canadian Maritimes will push an
east-west trough south across PA today.
Cold air aloft with moderately steep middle level lapse rates will
help to spark scattered rain showers...especially across the northern
and central mountains through middle afternoon. The hrrr shows this
activity continuing to grow into the afternoon hours before
dropping off rapidly after about 22-23z.
A subtle shortwave ridge will slide into the state from the north
later today and tonight. This will bring drier conditions...however
low clouds over northern and central areas may take some time to
mix out...with improvement likely holding off until Tuesday
Lows in the middle 30s to around 40 will be near to slightly below
Despite the recent spell of chilly weather...average temperatures for
the month are still running a bit above normal at many locations.
Short term /Tuesday/...
Slowly rising heights and the approach of high pressure at the
surface will bring a few days of dry and noticeably milder
conditions for Tuesday and Wednesday.
Tuesday will start off cloudy over much of the area...mainly the
north...before increasingly sunny conditions develop by late
morning and into the afternoon.
High temperatures Tuesday afternoon will climb back to near normal for
Long term /Tuesday night through Monday/...
A slow moving southern stream upper low will emerge into the southeastern to
Middle Atlantic States during the midweek period. A distinct and rather
potent shot of upper energy...in the form of a closed low
dropping south-southeast from the upper glakes region should capture the surface
low /progged by most 00z-06z model and ens guidance to be near the
Outer Banks of NC Thursday morning/.
Phasing of these features will coincide with the development of
highly anomalous east-nerly flow in the 925-850 mb layer late
Thursday into Friday across southern and eastern Penn.
Precipitable waters in excess of over 1 inch near the Delaware-Maryland-Virginia and southern New Jersey coast
will be transported nwwd up/over the shallow cold air entrenched
across central Penn and the susq valley.
Coordinated with surrounding weather forecast offices to boost probability of precipitation /and the
northeast to northerly wind/ for Thursday afternoon and night.
We even speckled in some wet snow mixing in late Thursday/Friday
morning across The Laurels at or above 2400 feet mean sea level.
The much cooler GFS/gefs temperatures appear more realistic at this
point as clouds thicken.../as rain develops across the region
form the south and west/ and falls through The Wedge of relatively
drier/cooler air near the surface.
Aviation /18z Monday through Saturday/...
MVFR ceilings have become established over the western and
northern higher elevation terminals and will continue into the
overnight. Brief IFR is possible with passing showers. Strato-cumulus
ceilings in the 3000-6000' range are covering the remainder of
the flying area.
Winds from 290-320 will gust up to 20kts at times this afternoon.
Look for showers to dissipate with the loss of heating with MVFR
ceilings likely lingering into Tuesday morning over western and
northern mountains. Elsewhere conditions should remain VFR with a
tendency for clouds to scatter out over the middle and lower susq
Tuesday...MVFR ceilings west improving to VFR by afternoon.
Wednesday...no sig weather.
Thu-Fri...MVFR possible in scattered rain showers.
Sat...no sig weather.
near term...la corte
short term...la corte