Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
844 am EDT Sat may 23 2015
a large area of high pressure will be overhead this morning before
sliding off the middle Atlantic coast tonight. A gradual warming
trend will begin Sunday...with warm and humid conditions in store
with a chance of a shower or thunderstorm each afternoon during
the Tuesday through Friday period. While a stray shower is
possible on Monday...most of the area will be dry through all of
Memorial Day weekend.
Near term /until 6 PM this evening/...
mesoscale observation show that temperatures even in the coldest spots up north have
risen well above freezing as of 1230z...with the Mercury rising
through the 40s in most other locations. The lower susq has temperatures
climbing into the lower 50s as of 1230z. The freeze warnings and
frost advisory for northern and central Penn expired at 12z.
It will warm up very nicely today...thanks to full late may
sunshine with just a few strands of thin cirrus and perhaps a few
pancake cumulus on the ridges this afternoon.
Maxes in the middle 60s up north...and around 70f throughout the
southern valleys will still end up below normal - and not more
than a degree or two milder than yesterday.
Short term /6 PM this evening through Monday/...
the surface high will drift to the S/east and off the coast
tonight/Sunday...and return flow will help warm things back up.
However...the clear sky and light wind will allow temperatures to again
dip to near freezing in the northern mountains. Have capped the
mins there at 33f for now and mentioned frost...but have stayed
away from a freeze watch. A slight westerly or southwesterly wind
may keep them just above fzg. Have also decided to not issue a
frost advisory just yet...and allow the current headlines to expire
and aviod perhaps conlicting/confusing headlines for now and
Sunday looks like Winner with seasonably mild temperatures and light west/SW
winds. Heights/thicknesses/8h temperatures rise nicely Sunday night and
Monday. Mins Sunday night will run a dozen or so degrees milder than
It now appears that the high will hold on a little longer on
Monday and keep most if not all of the showers at Bay and off to
our west. Have kept a very minimal chance for a shower in the north and
over the Poconos. But no rain outs or soggy picnics are expected
at this point. Maxes will be another 6-8f warmer than Sunday.
Long term /Monday night through Friday/...
all guidance continues to signal the warming trend...with high
confidence in above normal temperatures all week long as
anomalous 500mb ridge builds over the eastern U.S.
Some differences on placement of a warm frontal zone lifting northward
from the Southern Plains/lower MS valley which will have impacts on precipitation
risk early next week...though best daily probability of precipitation will be over the northwest.
Dewpoints will be mainly in the 50s the first part of next week
for most of the area. Southeast PA will likely see dewpoints in the 60 to
65 degree range...but not really that high for late may. Warm
front also forecast to lift well north of the area on Tuesday.
Thus based on these factors and other factors...did lower
probability of precipitation some...and edge temperatures up a degree or so.
Overall...not looking at temperatures or dewpoints as high
as recent events. Thus a nice Holiday weekend in store for the
area...and not a bad period of late Spring weather next
week...enjoy the Holiday weekend.
Aviation /13z Saturday through Wednesday/...
high pressure and associated dry air mass over Pennsylvania will
provide a certainty of VFR conds and light winds today.
Sun-Mon...no sig weather expected.
Tue-Wed...isolated PM thunderstorms and rain impacts possible West Mountains