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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 170331
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1131 PM EDT Thu May 16 2019

.SYNOPSIS...
A weak front will drop through the area Friday. This front will
remain close to the region keeping the mention of a shower in 
the forecast through the weekend into early next week. 
Temperatures will continue to moderate through the period.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
New convection is firing over southern Michigan/NRN Indiana and
looks aimed at SWRN PA. The HRRR shows this entering my western
zones between about around sunrise and mainly dissipating as it
passes through my SWRN zones. It does show scattered showers 
over much of the remainder of the forecast area, but the overall
coverage suggests being less pessimistic about the rain chances
late tonight and especially during the day Friday.

The increasing clouds and 5-10 mph SW breeze will lead to 
overnight min temps generally in the low-mid 50s.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
GEFS indicates Highest PWAT air (30-35MM over Western and 
Central PA early Friday) will sag south to the Southern Tier 
counties of PA by 18Z Friday, with negative LLVL Theta-E 
advection across the Central and North. PWAT values by late
Friday afternoon will dip to under 20 MM along the PA/NY border. 

Will layer pops for Friday afternoon from only 20-30 percent 
across the northern tier of PA where ML capes will be nil, 
to near 60 Percent across the Laurels, where CAPE will be on the
order of 1500-2000 J/KG.

Granted, there will likely be a sharper gradient, but there is 
still some uncertainty near and just south of the I-80 corridor 
whether a few stray showers could wet the ground or we'll see 
dry conditions after the brief bout of dissipating morning 
showers/isolated TSRA. 

Thunder chances are probably highest late tonight (west) and 
then again in the aftn, but mainly in the Scent and SW. SPC does
have much of the southern tier counties in our CWA within their
MRGL risk for svr storms on Friday (DY2).

Temps should rebound to the m60s in the N, but get close to 80F
along the MD border.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
*Trending warmer and more humid Saturday-Monday
*Dry breaks but still can't rule out a couple of showers or 
 t-storm through Monday
*Tuesday looks cooler/less humid with increasing chance for rain
 into midweek

Rising heights and building upper level ridging will spell a
warmer and more humid sensible wx trend through the weekend 
into early next week. While there will be plenty of dry breaks,
we still cannot rule out a few spotty showers or isolated 
t-storm during this time. Expect sparse coverage with limited
rainfall. 

We are fairly confident that Tuesday will be dry and 
and bit cooler/less humid. Model and ensemble guidance shows an
increase in rain risk heading into the middle of next week.

&&

.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
Clouds will gradually thicken and lower overnight. Ceilings 
should drop to MVFR (possibly IFR) over the western highlands 
/KJST and KBFD/ by daybreak, with brief vsby reductions 
possible in showers.

Included LLWS at all airfields overnight into Friday morning, 
as a 30-45 kt WSW low-level jet is expected to push across 
central PA.

A weakening area of shra/tsra could brush SW PA towards 
daybreak on Friday. A few additional shra/tsra are expected to
develop by afternoon, as a weak cold front crosses the area.

.Outlook...

Fri...AM low cigs and shra possible NW mtns. Scattered aftn 
shra/tsra impacts possible.

Sat...Isolated aftn shra/tsra possible western highlands.

Sun...Scattered aftn shra/tsra possible area-wide.

Mon...AM low cigs possible NW mtns. Scattered aftn tsra impacts
possible eastern PA.

Tue...mainly VFR.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...La Corte
NEAR TERM...La Corte
SHORT TERM...Lambert
LONG TERM...Steinbugl
AVIATION...Evanego