Scientific Forecaster Discussion
fxus61 kctp 281030
Area forecast discussion
National Weather Service State College PA
630 am EDT Wed Jun 28 2017
high pressure will move off the eastern Seaboard later today
setting up a warmer and more humid airflow beginning on
Thursday. A cold front on Saturday will bring a brief break in
Near term /through tonight/...
satellite shows patchy mainly mid clouds streaking southeast across my
eastern zones. Otherwise skies are clear to scattered and the
GOES r nighttime microphysics channel shows nicely how the
northern valleys have filled with fog.
The fog will burn off quickly under the high Summer sun leading
to a bright sunny day with highs averaging in the 70s. Quite
pleasant with a light wind, yet still several degrees cooler
than normal. It will be the last cooler than normal day we will
see for a while.
The high will move overhead today and east of the area by
tonight setting up a warmer and eventually more humid SW flow.
The overnight will see a gradual increase in clouds from the northwest
with another comfortable sleeping night in store with dewpoints
still only in the 50s.
Short term /Thursday/...
by Thursday the eastern US will be under a broad upper ridge,
but close to the southern edge of the main westerlies. A warmer
and more humid airmass will begin to advect into the region
between the offshore high and a low moving north of the gr
lakes. Deterministic models develop a fair amount of cape and
mid level lapse rates are forecast in the 6-7c/km range, so an
afternoon shower or thunderstorm is likely in a few spots. I
used the blended MOS pops to favor the northern 1/3-1/2 of my
County Warning Area for the best chance of rain in the afternoon.
Long term /Thursday night through Tuesday/...
the upper pattern starts out with the broad ridge and high
heights over the eastern US, before eventually becoming more
broadly cyclonic, but still with heights remaining seasonably
high as most shortwave energy slides through southern Canada.
Friday will be warm and humid with diurnally driven
showers/storms possible. The deterministic European model (ecmwf)/GFS both show
the mid levels being relatively warm suggesting coverage will
be on the scattered side.
A cold front is progged to be entering the region Saturday and
moving east of the County Warning Area early Sunday, so we should see a better
chance of more widespread rain. The front is expected to be
weak, so temperatures behind it will not change much, just a
bit of a break in the humidity for the second half of the
Sunday night into early Tuesday look mainly dry as high pressure
builds over the region. The cold front will begin sliding back
north as a warm front Tuesday into mid week, bringing renewed
humidity and increased chances for the usual summertime showers
Aviation /12z Wednesday through Sunday/...
high pressure building into the area from the Ohio Valley will
supply mainly VFR conditions and light wind today. Ipt and figure
have been the only sites to have IFR and lower restrictions.
Some mid clouds and variable winds stifled any fog development
over the northwest. The restricting conditions will continue for the
next few hours before wind can mix and dry out the low level. So
I have a tempo group until around 13z at ipt. Otherwise high
pressure over the region should ensure VFR conditions and light
winds for the rest of the day.
Thu-Fri...isolated PM tsra impacts poss, mainly northern PA.
Sat...scattered PM tsra impacts possible.
Sun...no sig wx expected.