Area forecast discussion
National Weather Service State College PA
224 am EDT Wednesday Jun 19 2013
Synopsis...
the persistent mean trough over the middle-Atlantic and northeast
states will be replaced by a upper level ridge migrating eastward
from the plains. This pattern will bring some of the warmest air
of the season to the area...with the increasing heat and humidity
arriving on schedule with the official start of astronomical
Summer. A typical summertime pattern should unfold next week as
the upper ridge shifts westward back into the Southern Plains and
the main jet stream takes up its usual residence along the
U.S./Canadian border.
&&
Near term /through tonight/...
radar shows the last of the showers drifting southward from South Mountain
across the Mason-Dixon line into northern Maryland. Northerly flow around high pressure
migrating southeastward from the Great Lakes will direct drier air into the
County Warning Area through the morning...ending the threat of precipitation across the far southern
tier. Infrared satellite shows low clouds will persist across the Laurel
Highlands and S-central mountains into the predawn hours...but in general
expect conds to improve heading into the daylight hours. Clear skies
will prevail over northern PA with daybreak temperatures dipping into the middle
40s.
500 mb heights will start to rise as the mean northestern Continental U.S. Trough finally
lifts out. High pressure will bring fair weather to the area today with low
humidity and pleasant/comfortable temperatures. Clear skies and low
precipitable waters will make for a chilly night especially across northern PA where
nighttime lows will fall into the low 40s/upper 30s. Mav guidance has
36f for bfd suggesting some patchy frost may even be possible.
&&
Short term /Thursday through Friday night/...
upper ridge over the plains states will shift eastward this period as
a deep closed low moves from the Pacific northwest into the northern rockies. 500 mb
heights climb above normal by Friday. Winds will veer around to the
south/southwest as the surface high moves off the middle-Atlantic coast. The
return flow will result in a gradual increase in daytime temperatures and
low level mstr/dewpoints/humidity. The warmer pattern will arrive on
schedule with the first day of astronomical Summer. Model data
suggests some isolated diurnal convection is possible along The Spine
of the appalchns...but for the most part expect most areas to stay
pcpn-free.
&&
Long term /Saturday through Tuesday/...
heat and humidity continue to increase heading into the weekend
as heights peak. Bigger surge of higher dewpoints slides in from
the west as heat continues to build...so a series of very warm and
humid days are in store for Sat into Tuesday...with overnight lows
remaining quite mild as well. With stagnant air and increasing
humidity on back side of surface high...held on to 20-30 probability of precipitation most
afternoons - with highest chances over western higher terrain of
isolated differential heating initiated storms.
Pattern also has a ring-of-fire look to it so will need to watch
for mesoscale convective system activity/ridge rollers sliding down from the northwest...though
latest models not quite as bullish on that. Ec overall producing
more convection than the GFS...but general areas are similar.
&&
Aviation /06z Wednesday through Sunday/...
scattered showers across the lower susq continue to weaken as the
evening progresses. Most sites will remain VFR overnight...but some
MVFR conditions are possible from jst eastward as the showers
meander about. Best chance for reduced conditions will be where it
rained this evening.
Any early MVFR over southern areas will improve shortly after sunrise
leading to widespread VFR Wednesday as high pressure builds out of
the gr lakes.
High pressure will control the weather into the weekend.
Outlook...
Thu-Fri...no sig weather expected.
Sat-sun...isolated PM thunderstorms and rain impacts possible.
&&
Ctp watches/warnings/advisories...
none.
&&
$$
Synopsis...steinbugl
near term...steinbugl
short term...steinbugl
long term...rxr
aviation...la corte/ceru
