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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

                            
000
FXUS61 KCTP 171925
AFDCTP

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

.SYNOPSIS...
A warm front overhead will likely stall out, but eventually lift
northward on Thursday. A complex frontal system will eventually
push a cold front through Friday night. A deep tropical 
moisture plume moving in on Friday will lead to widespread
showers and thunderstorms with heavy rainfall for late Friday 
into early Saturday. Flooding is possible Friday night and 
Saturday.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Temps have popped into the m-u60s SW of US 22 and I-99. Warm
front is inching northward right now, but will likely stall as
the heating of the day goes away. While the earlier forcing
which produced light rain over the central counties has moved to
the east, some diurnal cu are growing over the western mountains
and should produce isold-sct SHRA this evening. 

As the front stalls and the light ESE flow brings in higher
moisture, it should rise and form low clouds. However, the lack
of low clouds along the Atlantic coast could be a negative sign
for that part of the forecast. But, our elevation change from
the coastal plain to the piedmont and Poconos/central mtns
usually helps rise/cool/condense. Will stick with the going
forecast of low clouds and patchy DZ/isold SHRA later tonight
and Thurs AM. Expect temps to be very mild overnight with mins
only in the m-u40s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
Thursday will feature the best weather until at least Monday. 
The front should be overhead in the morning. It should begin to
lift and the low clouds will start to scour out. A patch or two
of DZ is possible in the morning over the east where the low 
clouds will be thickest/last longest. Depending on the extent 
of the low clouds, it will take a commensurate amount of time 
to scour the junk out. At this point, much of the area should 
break out to a mostly sunny day. Most maxes will be in the upper
60s to lower 70s in the south and west (or 7-10F above normal).
Will keep the NE third of the area in the l-m60s. Although a 
stray/brief shower can't be ruled out, the bulk of the region 
will see no rain in the late morning and afternoon hours.

&&

.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 /19Z WEDNESDAY THROUGH MONDAY/...
A stationary front will waggle north a little this evening, but
perhaps wash out. A few showers will develop along and north 
of the front, mainly over the Alleghenies (KFIG/KBFD) where
heating is popping some cumulus. The clear air just S of KJST
should slide N as the front inches northward. But, some low
clouds may come back into KJST overnight. 

As the front begins to drift northward tonight, the light E/SE 
wind in the eastern half of the state will likely help to create
low clouds and perhaps some IFR and drizzle. The ceilings 
should be higher over the west, with improvement during the late
morning over much of the area. Some stratus may linger into the
aftn in the east/mainly KIPT.

Low pressure moving through on Friday and Friday night will
produce widespread showers and thunderstorms. Breezy Sat with
typical post-frontal flow. 

.Outlook...

Fri...Mainly VFR AM, SHRA/TSRA developing,
Fri night...Widespread restrictions. 
Sat...Widespread fog/cig with IFR in the morning with 
improvement thru the day. Scattered showers, mainly west. 
Sun...MVFR likely NW half, otherwise no sig wx.
Mon...Mainly VFR. Brief period of MVFR with a chc of showers.

&&

.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/Martin
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Martin
AVIATION...Dangelo
HYDROLOGY...Dangelo