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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 180317
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1117 PM EDT Wed Apr 17 2019

.SYNOPSIS...
A stationary front over southwest Pennsylvania will lift north
through the rest of the state Thursday afternoon. A slow moving
cold front will push into the region Friday, then stall out in
the vicinity of Pennsylvania this weekend.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Upper ridging building over the region should result in a dry
night for most of central Pa. However, some weak fgen forcing, 
combined with shortwave tracking across the eastern Grt Lks, 
could potentially produce a few showers overnight across the 
northern counties. 

SREF prob charts continue to suggest radiational cooling, 
combined with a moist southeast flow off the Atlantic, will
result in developing stratus toward dawn across central and
eastern Pa. An examination of model soundings suggests cloud
depth will be too shallow to support drizzle, so have removed
mention in the forecast. Superblend/NBM min temps are in the
40s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
Thursday will feature the best weather until at least Monday. 
NAM surface theta-e fields indicate the approaching warm front 
will lift northward into the Laurel Highlands by midday and
reach roughly to a KBFD/KUNV/KMDT line by late afternoon. Expect
brightening skies and much warmer conditions south of the
boundary, but lingering clouds and coolness across the 
northeast portion of the forecast area. 850mb temps support 
highs in the 70s south of the front, while the high terrain 
north of KIPT could struggle to reach 60F.

Upper ridging centered over eastern Pa should keep most of the
region dry Thursday. However, diurnal heating, combined
approaching trough over the Grt Lks, could support a few
afternoon showers over the northwest portion of the forecast 
area.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
A deep low lifting northward across the Great Lakes will tend to
slow down and cutoff at some point late this week or early next
week. This system will pull a cold front across the area late
Friday into Saturday. 

Would expect some thunderstorms, but looks like the warmer air
gets pushed off to the east rather fast, so main threat of
severe weather would be further south, and the heaviest rain
likely across the far eastern areas and points to the north and
east of our area.

While it will start off mild, the Easter weekend looks to be
cold and wet. Best chance of dry and sunnier conditions will be
later on Easter Sunday.

Another cold front on Monday, followed by high pressure trying
to build southward. Still some chance of showers at times, given
the front being nearby.

See hydro section below for more detail on the potential for 
heavy rain.

Overall, just minor adjustments made to the forecast.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
A light SE wind is already bringing low clouds into the Lower 
Susq Valley, and these will likely expand northwestward 
overnight. IFR cigs are possible over the east, but cigs should 
remain a bit higher over the west. Improvement is expected by 
late Thurs morning over much of the area, although some low 
cloudiness may linger into the aftn in the east.

Low pressure moving through on later Friday into Friday night 
will produce widespread showers and thunderstorms. It could 
remain a bit showery into the weekend, as upper-level low 
pressure slowly passes overhead.

.Outlook...

Fri...Mainly VFR AM, with deteriorating conds by aftn with 
SHRA/TSRA developing.
Fri night...Widespread restrictions in SHRA/TSRA.
Sat...Widespread restrictions in the morning with improvement 
thru the day despite scattered SHRA lingering.
Sun...Scattered SHRA persist.
Mon...Mainly VFR. Late-day showers possible.

&&

.HYDROLOGY...
Rainfall from showers and thunderstorms on Fri/Fri night could
be enough to produce flooding. Latest runs having that 
convective look to the precip with big stripes of heavy/intense 
rain and gaps in between. No solution in particular should be 
followed verbatim when it comes to QPF. Model solutions 
generally keep the heaviest rain over the east, with relatively 
lighter amounts elsewhere. The tribs in the east will be the
most likely places to have sig rises and perhaps flooding. The
larger waterways (Susq, Juniata) should be fine until at least
Saturday or Sunday if they ever get high.

&&

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

&&

$$
SYNOPSIS...Dangelo/Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Dangelo/Fitzgerald
LONG TERM...Martin
AVIATION...Evanego
HYDROLOGY...Dangelo