Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
1105 PM EDT Wednesday Oct 1 2014
a slow moving upper level low will move east of the commonwealth
through tomorrow. A strong cold front will push into the
commonwealth Friday night and Saturday.
Near term /until 6 am Thursday morning/...
cloud cover and areas of fog will be gradually increasing over the
next few-several hours...considering the current tight 1-2 degree f
temperature/dewpoint spread and light/variable wind with a ridge of high
pressure at the surface and aloft building east across the County Warning Area.
Earlier scattered showers have fizzled out across the susq valley
as the weak forcing from an upper vorticity lobe shifts southward toward the
southeastern corner of the state.
Expect areas of 1/4-1/2sm fog to form once again. Held off on a
dense fog advisory for now after coordinating with surrounding
weather forecast offices /and considering the trend of increasing upslope southeasterly flow
and stratus forming in many locations after 05z/.
Low temperatures will be in the 50-54f range around 11-12z.
Short term /6 am Thursday morning through 6 PM Thursday/...
little mixing to be had during the morning hours tomorrow...so
the fog/stratus which does form could take more than just a few
hours to burn off. Otherwise...with ridging overhead instead of
the upper low of Wednesday...it should turn out much sunnier...and
almost no chance for a shower. Maxes will be slightly warmer than
Wednesday...reaching the lower to middle 70s throughout the County Warning Area.
Long term /Thursday night through Wednesday/...
progressive upper low/compact trough axis forecast to be lifting NE
into New England at the start of the period will be replaced by
a short period of rising heights late in the week. A second...much
stronger and expansive upper trough axis extending southward from an upper
low anchored over northern Ontario is forecast to sweep across the
eastern U.S. Over the weekend.
Warmer weather makes a brief return Thursday...Friday and early Sat as
the upper ridge temporarily rebuilds....with most maxes and mins
at least several degrees above climatology normals. Maximum temperatures Sat will
be below normal.
The arrival of the second trough will support a strong cold front
with deeper connections to the Gomex and the Atlantic
Ocean...thus potential for more widespread and heavier
rainfall than with the first front. Passage of the front will
also bring noticeably cooler temperatures to the region starting
Saturday afternoon into Monday.
Several short waves dropping into the upper trough / expected
cyclonic flow over the region will keep the weather cool and
unsettled into early next week.
Aviation /03z Thursday through Monday/...
a few showers that slid in from the east have all but dissipated
at 03z...with maybe a sprinkle lingering around klns. North-S oriented
cloud deck at 3000-4000 feet /associated with earlier showers/ will
erode over the east. Remaining County Warning Area mainly clear this mid-evening.
But models continue to slide moisture up into the central mts on
light but persistent S/Erly flow. Therefore...will bring another
stratus deck into the forecast overnight for almost all sites.
Perhaps only bfd will remain mclr overnight. But fog is expected
everywhere overnight/Thursday morning...with areas of IFR visibility
impacting west and central terminals. The light east/southeast wind does
not Bode well for quick clearing/dissipation of the fog and any
morning stratus after sunrise. But by late morning conditions will
evolve to VFR.
A very strong upper level trough will drop down through the upper
Midwest and Ohio Valley on Friday...and bring a strong cold front
through Friday night. Preceding the front will be a srly wind
which could make low level wind shear on Friday....but gusts will be more-likely
as mixing brings those strong 30-35kt winds down. Thunder is
expected late Friday and through Friday night. Showers may linger Sat am
in the east.
Sat...am showers eastern areas. Breezy with improving conditions east of
the mountains isolated showers and MVFR ceilings over North/Western areas.
Sun-Mon...MVFR ceilings possible northwest...otherwise VFR.