Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 281051
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
651 AM EDT TUE JUN 28 2016

.SYNOPSIS...
A cold front will move slowly across the area today. High
pressure will bring a period of drier weather for mid week.
A new frontal system will approach for the end of the week.

&&

.NEAR TERM /UNTIL 7 PM THIS EVENING/...
Fog rolled quickly into the local area in the last hour, but is
lifting rapidly as well. Mentioned patchy fog for the next couple
hours in areas which cleared out overnight. Otherwise, no changes
forseen.

prev...
Sharp dewpoint gradient overhead right now. HPC has a front
analyzed near KERI and it does appear to be slipping this way. A
second trough - perhaps a lee trough - is centered over the state
N-S. It appears from the latest surface analysis that the fronts
are merging in western NY and over the northern PA mountains,
stretching back to KPIT. The lee trough is holding steady. As the
morning continues, the main front will be sliding E/S.

Best chance for showers still looks to be to the east of KUNV this
afternoon. Upper trough finally swings into the west during the
day today. Latest meso models do pop things up over the
alleghenies or slightly more to the east mid day or early
afternoon. NAM takes a bit more time to cook up the convection
and holds it off until mid afternoon which makes it go up
generally to the east of UNV. Thus POPs will run highest in the
eastern zones, but still hold in the chc range for the central
counties. The challenge with today`s forecast is the potency of
the thunderstorms. SPC has the eastern half of the area in the
MRGL risk and the far eastern 5-6 counties in the SLGT risk.
Dewpoints/available fuel is high and temps cool slightly aloft
thru the day. Fronts/boundaries around should make for triggers.
Many questions abound, though. We should get some really good sun
in the Central & NE sections of the CWA this morning. There
appears to be a decent capping inversion around 10kft. The wind
speed profile is also marginal for severe with the lowest 50kt
winds above 20kft. Deep-layer shear of around 40kts is, yet
again, marginal for severe winds. Low level convergence and
directional shear is interesting with a hodograph that does turn
nicely - albeit not all too drastic with the speed. The NAM is
most aggressive with CAPEs >1500J/kg and GFS (and so far the RAP
& HRRR) lacking in CAPE with less than 500J/kg at KIPT this aftn.
At this point, we will lean toward SPC guidance but am leary that
we can realize all that CAPE today.

Maxes today will run a little cooler than normal in the NW where
the 8H temps will be down close to +10C this afternoon and a mid-
deck may slide over them in the afternoon. Temps should be nearly
normal over the rest of the area.

&&

.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Much drier air will allow the temps to drop off nicely tonight.
There might even be some U40s in the northern mountains. The
showers will probably linger in the east until midnight or a
little later with the upper trough not in any hurry. Dewpoints
don`t get below 60F in the SE and a little wind will likely stop
the temp fall in the L60s there. A little fog is possible, mainly
in the SE where the dewpoints and residual rain/moisture are
highest. But the light wind may keep it from forming. Will just
mention here. Low clouds are possible in the NW directly
underneath the cyclonic flow of the upper low which stalls briefly
over western NY.

Wednesday looks stellar for late June. Temps near normal and
a mostly sunny sky after any morning low clouds burn off. Just a
little wind with the 6mb gradient across the state. On the
possibility of a shower in the afternoon over the far northern
tier: dewpoints there will be near 50F at that time, so there
isn`t much of a chance.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Mid week looks mainly dry as upper heights rise with a weak mid-
level shortwave ridge.

By Friday the upper low bottoms out south of James Bay as it
tracks eastward. Models are having a hard time resolving
individual shortwaves rotating around this system, but there is
better consensus tonight in the next chance for showers coming
along about Friday with the approach of a new cold front moving in
from the west.

At this point the weekend looks mainly dry with high pressure
building out of the Great Lakes suppressing rain south of the
border. Temperatures through much of this period will be near
normal.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Made a few adjustments so far this shift.

At 06Z backed off on the fog some.

Since then...lower cigs across the southeast...thus backed
off more on the fog.

Further west...conditions not bad.

Main change to 09Z TAFS was to adjust fcst for UNV. Took a
walk outside the office...and an area of fog and low cigs
came in from the south.

Anyway...expect most sites will be VFR by late morning...as
the strong June sun works on the clouds.

Some chance of showers and storms this afternoon into this
evening. However...did not get much yesterday...mainly just
east of State College after sunset. While the upper level support
is better today...need to bring the low level winds more to the
SE...to see widespread showers and storms.

After this evening...most of the week looks to be dry...with
mainly VFR conditions...as a drier airmass works into the
area.

OUTLOOK...

Wed...Early morning fog possible east.

Thu...No sig wx expected.

Fri...Isold PM tsra impacts possible.

Sat...No sig wx expected.

&&

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

&&

$$
SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...La Corte/Gartner
AVIATION...Martin


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