Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
128 am EDT sun may 24 2015
a large area of high pressure over the central Appalachians will
drift east to the Delaware-Maryland-Virginia coast tonight. A gradual warming trend
will begin Sunday as a light southerly flow develops...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 7 am this morning/...
1015 PM update...
all is well. Minor tweaks to sky and temperature trend. Still looking
like patchy frost is definite in the north as dewpoints now up
near freezing - quite a bit higher than last night at this time.
If they rise more it might just be dew.
we were treated to a splendid start to the long Holiday weekend
with a near perfectly clear azure Blue Sky earlier today...along
with light wind...low humidity...and mild temperatures...thanks to a
large area of high pressure that is currently located just off
the Delaware-Maryland-Virginia coast.
Clear skies and wind dropping off to nearly calm later tonight
will combine with anomalously low precipitable waters /and surface dewpoints mainly
in the middle 20s to lower 30s/ to allow temperatures to plunge into the
middle-upper 30s for lows up north...and lower to middle 40s elsewhere.
Patchy frost will occur throughout the colder valleys of northern
Penn...but it/S extent and duration shouldn/T be enough to warrant
a frost advisory.
Short term /7 am this morning through 6 PM Monday/...
the area of high pressure will drift to the east and off the
Delaware-Maryland-Virginia coast Sunday...and a light southerly return flow will
help warm things back up. Highs Sunday afternoon will be in the
lower to middle 70s across the mountains...and near 80f in southern Penn.
Heights/thicknesses and 800 mb temperatures all rise nicely Sunday night and
Monday. Mins Sunday night will be noticeably milder than Sunday
12z gefs indicates that Monday should be dry across much of the
region. Warm front across our far NE zones and the close proximity
of a nwrly upper jet across the Hudson Valley of New York and New
England could spark a stray rain showers or thunderstorms and rain there...while increasing
precipitable waters streaming NE from the Ohio Valley may trigger a similar
stray late day thunderstorms and rain across the western mountains
Maximum temperatures will be another 6-8f warmer than Sunday.
Long term /Monday night through Saturday/...
warm air air advection will continue through the first half of
the week. The ridge will tilt eastward and the flow will shift to
the southeast as an upper level low begins to dig into the Upper
Middle west...and extend down through the Ohio Valley. The 500 mb
anomalous ridge will still exert its affect on the region as
temperatures should remain warmer than normal through the period.
The warm front will lift through the area Tuesday into Wednesday.
There continues to be some variation on the placement of the
boundary...and will allow for some changes on precipitation
probabilities and quantitative precipitation forecast amounts. The best moisture should be 00z to
12z Wednesday. With the best precipitation continues to be through the
northern half of the state. Have increased pop chances
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.
Overall...temperatures should stay above normal as the anomalous
ridge keeps the cooler air up north...and precipitation chances
increase through the middle and later half of the week in frontal
Aviation /06z Sunday through Thursday/...
another nice day in store for the area today...just a few
middle and high clouds late.
VFR conditions likely to prevail prior to 09z Tuesday.
No big changes to 24/06z tafs from the 03z intermediate update.
VFR conditions will continue into early this week...with an
increasing risk for afternoon showers and thunderstorms through the end of
the period. Predawn/early morning fog will also likely start to be a
factor given return of Summer-like pattern with much higher
dewpoints and light winds by Tuesday.
Tue-Thu...patchy a.M. MVFR fog/br. Isolated-widely scattered p.M. Thunderstorms.