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Area forecast discussion 
National Weather Service State College PA
1012 am EDT Monday Jul 25 2016

Synopsis...

A cold front will push southeast across Pennsylvania late today
and tonight. High pressure will return for mid week with
continued warm temperatures. Temperatures may trend back to near
or slightly below normal over the weekend.

&&

Near term /until 6 PM this evening/...

Issued an update to upgrade the heat advisory to an excessive heat
warning for the sern zones today.

A hot and humid airmass is place across the region ahead of a
cold front currently extending from Southern Lower Michigan...sswd
to the Chicago area.

Early visuals show mainly scattered clouds so there will be little
to inhibit strong solar heating in the already very tropical
airmass. Rap analysis shows pwats in the neighborhood of 2 inches.

The southern 2/3 of the County Warning Area is under a slight risk today with the
primary triggering mechanisms being the cold front a potent mid
level trough that will push a well defined upper jet entrance
region over southern New York and northern PA.

The ncar ensemble shows a high probability of CAPES exceeding
3000j during Max heating. Models also develop some impressive
helicity as the system enters the region.

Lagging upper trough and sfc cold front will combine with the deep
tropical moisture to bring the threat of some training storms with
highly localized very heavy rainfall of 2 inches or more per hour.

Headwater flash flood guidance values are extremely high and
4 inches plus for the 1-3 hour period, so at this point there
isn't a big concern for flash flooding. However, pwats are just
about as high as they get around this part of the country, so the
biggest threat will likely be Urban and Small Stream flooding.

Ens mean 8h temps support Max temps today from the u80s across
the Allegheny plateau, to the m90s across the susq valley.

&&

Short term /6 PM this evening through 6 am Tuesday/...
the relatively weak sfc cold front will slide southeast across the southeast
half of the state late today and tonight, accompanied by
scattered showers and perhaps a few tsra early tonight.

Clearing skies lower precipitable water air, and a rather light west-northwest breeze of 5
kts or less could lead to some patchy dense stream/River Valley
fog...esp north late tonight and early Tuesday morning.

Low temps early Tuesday will vary from the l60s across the
north...to the lower 70s across the southeast zones.

&&

Long term /Tuesday through Sunday/...
big story in the extended fcst is the likelihood for modest
cooling by Tue/Wed behind the weak cold front. However, temps
still likely to remain somewhat abv normal within a generally
zonal flow.

Midweek weather looks dry again, with just low pops for isolated
tstms. Fri looks to be the next higher chance for tstm impacts
areawide as another cool front progged to move through.

&&

Aviation /14z Monday through Friday/...

Widespread VFR will continue into the afternoon before a line of
showers and thunderstorms brings localized restrictions to
affected terminals. Some of the thunderstorms could cause damaging
wind gusts and large hail, especially over the southern portion
of the flying area.

Dewpoints will not dip all that much tonight, so areas of fog
look like a good bet after the thunderstorms move east of the
region. For now will forecast 3-5 miles but would not be
surprised to see local IFR conditions develop. The best chance for
dense fog will be at terminals that see rain today and clearing
skies tonight.

Air does get slightly drier for the middle of the week. It should
not be cold enough at night to make much if any fog in the valleys
of the north. The airfields will likely stay VFR into Thursday.

Outlook...

Tue-Wed...VFR.

Thu-Fri...mainly VFR. Scattered PM shra/tsra.

&&

Climate...
record high for Harrisburg today is 99 degrees set in 1940.

Record high for Williamsport is 100 set in 1934.

&&

Ctp watches/warnings/advisories...
heat advisory from 3 PM this afternoon to 8 PM EDT this
evening for paz027-028-035-036-049>053-058.
Excessive heat warning from 3 PM this afternoon to 8 PM EDT
this evening for paz056-057-059-063>066.

&&

$$
Synopsis...la corte/Lambert
near term...la corte/Lambert
short term...Lambert
long term...Lambert/gartner
aviation...dangelo/la corte
climate...

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