Area forecast discussion
National Weather Service State College PA
516 PM EDT Wednesday Jun 19 2013
Synopsis...
high pressure over the area will bring chilly temperatures
to the area tonight. As this high pressure system moves
to the southeast by the end of the week...a warming trend will set
in. Mainly warm and dry conditions will prevail this weekend
and much of next week. There will be a chance for a shower
or thunderstorm now and then after Sunday...but most of the
time it will remain dry. A cold front could bring more in the
way of widespread showers and thunderstorms to the area by
late next week.
The warming trend will be in line with the start of Summer.
The official start of astronomical Summer early Friday morning.
&&
Near term /until 6 am Thursday morning/...
visible Sat imagery shows mostly sunny skies across central
PA late this morning...with fair weather cumulus cloud streets forming along
the nerly shear axis. Drier air mass and building subsidence inversion
should be sufficient to keep skies mostly sunny this afternoon.
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 temperatures about 3 to 5 degrees below seasonal normal.
Received several observer reports earlier this morning of min
temperatures in the upper 30s across northern tier counties. With clear
skies and low precipitable waters expected tonight...will make for another chilly
night overnight tonight especially across northern PA where nighttime
lows will fall into the upper 30s.
The GFS-based mav guidance has 37f for bfd suggesting some patchy
frost may even be possible. This is the lowest MOS guidance when
compared against the NAM/met...ec/ecm and is on the low end of
the 18/00z ecens members.
&&
Short term /6 am Thursday morning through Thursday 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 an increase in daytime temperatures and low level
moisture/dewpoints/humidity later Thursday.
&&
Long term /Friday through Wednesday/...
the warmer pattern will arrive on schedule with the first day of
astronomical Summer /see climate section for more details/. Model
data suggests isolated diurnal convection is possible along The Spine
of the north-central appalchns into the Laurel Highlands/S-cntrl
ridges...but for the most part expect most areas to stay rain-
free. Capping inversion may be a limiting/negative factor for
terrain-induced thunderstorms later Friday after. Left the forecast dry for now.
Northern rockies 500mb trough will eject northeastward into the S-central
Canadian prairies over the weekend...allowing the subtropical
ridge to retrograde and expand westward back across the Southern Plains. With
broad subtropical ridging covering the southern 1/2 of the Continental U.S....the
jet stream will be confined along the US/Canadian border - which
is where it should be for this time of year.
Thus looking at mainly dry and warm conditions into at least
the middle of next week. The main threat of showers and storms
would be north of PA...but a slight chance to chance of a shower or
storm will be possible after Sat...as any weak system could
touch off some...given higher dewpoints and terrain features.
While temperatures come up...dewpoints really not expected to be
anything abnormal. Looking at mainly temperatures between 80-85f across the
alleghenies and 85-90f east of the mountains in the central ridges and susq
valley. The main area of extreme conditions will be further west
across the plains.
&&
Aviation /21z Wednesday through Monday/...
Expect widespread VFR into Friday...as high pressure and dry air
build into the region.
High pressure will control the weather into the weekend. There will
be a slight chance to chance of a shower or thunderstorm sun and Monday...
but most areas will remain dry with VFR conditions.
Outlook...
Sat...no sig weather.
Sun-Mon...isolated PM thunderstorms and rain impacts possible.
&&
Climate...
astronomical Summer begins at 104 am EDT on Friday June 21st.
&&
Ctp watches/warnings/advisories...
none.
&&
$$
Synopsis...gartner/Martin/steinbugl
near term...gartner/Martin/steinbugl
short term...Martin/steinbugl
long term...Martin/steinbugl
aviation...la corte/Martin
climate...
