Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 200323
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1023 PM EST Mon Feb 19 2018

.SYNOPSIS...
Rain should shift north of the PA/NY border tonight as mild air
begins to move into central PA. A spring-like surge of record-
challenging warmth is expected Tuesday and Wednesday with
temperatures 25 to 35 degrees above average - making it feel
more like May than February. Expect the anomalous warmth to be
trimmed back later in the week but readings will stay above
average for this time of year. Periods of rain are likely during
the second half of the week into the weekend with brief
intervals of mixed precipitation possible over north-central PA
Wednesday night into early Friday morning.

&&

.NEAR TERM /UNTIL 8 AM TUESDAY MORNING/...
Fog is still the interesting part of the forecast. The thickest
stuff is in the calm valleys of the east, but that seems to have
improved despite some breaks in the clouds/clearing (except for
high clouds). The warmer hill tops are VFR. Some sites have
improved really well in the last few hours (DUJ & FIG for
example). Imagine that this trend will continue as the warmest
air works east - but only just a little. No need for a dense fog
advy just yet. Temps also difficult with the valleys of the
central and northeast cooling a bit. They should start to feel
the warmer air sink a bit, but have trimmed temps slightly
overnight there.

Prev...
Rain on track to lift out of that northern-most tier of PA
counties slowly through the next 3-4hrs. Fog has already begun
to get thick in spots across the south where clouds briefly
broke up. Will continue to mention fog across most of the area
overnight. The Laurels and perhaps Warren/McKean counties could
be spared the fog. However, it could get dense elsewhere. Will
keep an eye on the conditions for a dense fog advy (widespread
<1/4sm).

Prev...
Meso analysis at 2PM shows the warm front from central OH
eastward into NRN WV then down stacked up into the mountains of
western VA. Locally the nose of a SW LLJ is helping force some
warm advection/isentropic lift and an area of steady light-
moderate rain over about the northern 2/3 of my CWA.

The synoptic scale warm front is made to pass into NY state this
evening while the low level feature, a remnant of cool air
damming is slower to move northward through the Central
Mountains. The bulk of the rain will lift north with the deepest
forcing during the evening hours with the remainder the forecast
area seeing mainly damp conditions with areas of fog and maybe
some patchy drizzle. Can`t completely rule out a rumble of
thunder across the NW where the models develop some modest
instability.

Western higher terrain will tend to see the warm air mix down
first overnight with some breaks in the clouds and not as much
misty fog or drizzle.

Temperatures will be steady or slowly rising over most of the
area overnight as southerly flow freshens.

&&

.SHORT TERM /8 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
Tuesday will bring an early taste of spring as the warm air
mixes down to the surface over all of the forecast area
bringing near record warmth. Even conservatively mixing to just
925mb should yield max temps of 70-75F over the southern part
of the forecast area, with the coolest temps across the
northern mountains where they will hold onto clouds and a small
chance of showers the longest.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
*Record-challenging warmth Tuesday night through Wednesday
*Periods of rain with a brief interval of mixed precip possible
 Wed. night- AM Fri. over north central PA
*Pattern favors above average temperatures this weekend into
 next week

A very mild, spring-like start to the period with patchy fog
Tue ngt into AM Wed. giving way to a mix of clouds and sun with
near-record to record high temps across much of central PA.
Rain showers will accompany a cold front NW-SE across the area
from midday Wednesday through Wednesday evening. The front will
become quasi stationary near the MD line Wed. night. The wavy
frontal boundary will bring periods of rain into the weekend,
with an interval of mixed wintry precip possible north of the
front over north-central PA between Wed. night and early Friday
morning. Confidence is low on the ptype details but there is at
least some risk for a light snow and/or ice accumulation.
Another round or two or rain is likely over the weekend. We will
need to monitor the potential for flooding especially across
south- central PA where the ground is very saturated from
previous rain/snowmelt and streamflows are well above normal.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
The warm front continues to lift to the north and the
predominate IFR cigs and vsbys are slowly improving. In a bit of
a reversal, BFD, JST and UNV are all VFR with IFR cigs still
possible at BFD, while AOO, IPT, MDT and LNS are all IFR and
lower in cigs and vsbys. Expect the IFR and lower to continue as
it is based on trapped moisture and due to the calm winds. Once
the inversion lifts tomorrow morning, between 13Z to 15Z,
expect for these conditions to improve.
There is also the potential for LLWS with SW flow just off the
deck around 40-50 kts.
So all terminals will improve to VFR by mid to late morning.
Bradford will be the exception with the warm front hanging close
by keeping sub VFR conditions in place most if not all day.

Outlook...

Wed...Restrictions likely in rain showers mainly NW half.

Thu-Sat...Intermittent restrictions in rain showers .

&&

.HYDROLOGY...
Recent rainfall and snowmelt has resulted in very saturated soil
and well above normal streamflows across much of the area
especially south-central PA. Rainfall of 0.50 to 1.00 inch is
forecast between Wednesday and Thursday night, with additional
rainfall likely into/over the weekend. River flood potential
(including small streams, creeks and tributaries) is above
normal and we will continue to monitor the risk in the coming
days.

&&

.CLIMATE...
Record highs for selected sites for Tuesday and Wednesday
February 20th and 21st:

MDT: 72/1930;71/1997
IPT: 67/2016;69/1930
BFD: 58/2016;64/1997
AOO: 62/2016;71/1997

&&

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

&&

$$
SYNOPSIS...La Corte/Steinbugl
NEAR TERM...Dangelo/La Corte
SHORT TERM...La Corte
LONG TERM...Steinbugl
AVIATION...La Corte/Ceru
HYDROLOGY...
CLIMATE...


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