Scientific Forecaster Discussion
fxus61 kctp 231958
Area forecast discussion
National Weather Service State College PA
358 PM EDT Sat Jun 23 2018
a warm front will move into the region this afternoon and a cold
weak cold front will pass through this evening. A secondary
cold front will settle south through the area Sunday. Sunshine
and lower humidity will return Monday and Tuesday. A new frontal
system will bring more showers ahead of hot and humid weather
that will become established late next week into early July.
Near term /until 6 am Sunday morning/...
prospects for severe storms are very dependent cloud cover, and
seem to be dwindling as thus far the clouds over the slight
risk area continue to stubbornly hold on.
As of 18z the warm front remains between jst and aoo with breaks
in the clouds most evident over The Laurels up into the northwest
mountains. This is where the rap has the most cape, which is not
very much. Mixed layer CAPES are just topping 200j and mid level
lapse rates are pretty weak.
The slight risk area accounts for a small sliver of my southeastern
zones where low clouds and an easterly wind are hanging tough.
The warm front and a true wind shift to the SW look like it has
just gone through hgr.
Latest rap still predicts surface based cape of 800-1200j over my
Maryland border counties from about 19-23z along with deep layer
shear in excess of 40kt. If this can still manage to happen,
scattered strong storms will be possible, but my confidence at
this point is low.
Storm Prediction Center maintained a small portion of the lower Susquehanna valley
with a slight risk and the marginal risk north/west to cover
the remainder of south-central PA. Damaging wind will be the
Coverage of showers will diminish later this evening with just
an isolated shower possible after midnight. Some low clouds in
the increasingly humid airmass will be possible, and if any
measure of clearing can happen fog will also be possible. The
best chance will be over the southeast.
Short term /6 am Sunday morning through 6 PM Sunday/...
a secondary cold front will push south through the state
tomorrow and tomorrow night with more scattered showers and
storms. Drier air will follow in its wake. The best chance for
rain looks to be over about the northern half of the forecast
It will be warmer than today and quite muggy as dewpoints are
expected to be well up into the 60s in most areas.
Long term /Sunday night through Saturday/...
*dangerous heat conditions possible late next week/weekend
A cold front will clear the area Sunday night, with Canadian
high pressure directing a less humid/more comfortable air mass
into PA early next week.
A two-day stretch of pleasant, dry weather with comfortable
humidity is expected Monday and Tuesday. Added a few degrees to
maxt and shaved tds a bit based on abnormal dry airmass for late
June. Valley fog is a good bet Monday night/am Tuesday
especially across north-central PA with low temps in the mid
Showers and thunderstorms return for midweek followed by
building heat and humidity late week. While there are some
timing issues which is not unusual at this range, there has been
a fairly coherent model signal for the next round of
showers/storms to hit the area on Wednesday.
The big story during the second half of next week (possibly
lasting into early july) will be the hot/humid conditions
becoming established across the mid-Atlantic/northeast states in
association with anomalous upper ridge. Max heat index grids for
Friday suggest the potential for heat advisory conditions
across the Susquehanna valley. Will highlight the heat risk in
the severe weather potential statement.
Aviation /20z Saturday through Thursday/...
the eastern flying area is north of the warm front and has
managed to hold onto fairly widespread IFR and MVFR ceilings.
Breaks have developed in the warm airmass over western PA into
The Laurels where more numerous showers and thunderstorms have
developed in the unstable airmass.
Scattered thunderstorms will spread eastward into the central
areas and eventually eastern areas through the early evening
hours. Storms should exit the eastern airspace by midnight.
Lingering showers are possible across the western airspace
tonight with weak westerly upslope flow and residual moisture
resulting in MVFR to IFR cigs at kbfd/kjst into Sunday. Another
round of showers/storms is expected on Sunday.
Mon...low cigs psbl north/west airspace early, then improving.
Tue...patchy valley fog in the morning, otherwise VFR.
Wed-Thu...thunderstorm impacts likely.