Area Forecast Discussion
Issued by NWS State College, PA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
847
FXUS61 KCTP 240748
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
248 AM EST Fri Feb 24 2017

.SYNOPSIS...
Our extended period of very mild weather will continue into
Saturday morning. A strong cold front will push east across the
region on Saturday and create showers and perhaps some gusty
thunderstorms. Gusty westerly winds, colder temperatures, and
snow showers across the western mountains will follow the
frontal passage. A wave of low pressure moving up the Ohio
River Valley on Monday may bring some mixed precipitation to the
northern half of the area and rain in the south.

&&

.NEAR TERM /UNTIL 8 AM THIS MORNING/...
Early morning temperatures (in the mid-upper 40s across the NW
mtns to the upper 50s in the SE) are running 20 to 30 degrees
above normal for late February. Temps will fall little more than
a few more deg F early today, thanks to abundant mid and high
clouds and a tight, few-svrl deg F T/TD spread.

Deep layer moisture continues to increase ahead of an
approaching shortwave trough from the Ohio Valley...allowing new
showers to form over the northern tier counties of PA, and
portions of the Susquehanna`s West Branch.

Based on the latest HRRR, these showers will stay limited to
the region north of Interstate 80 through the mid morning hours
today. Cloud tops aren`t really cooling and the rain cores in
the showers and their echo tops of 15-20 kft are quite low, so
do not expect to see thunder. Rather, some very brief downpours
amounting to just 1-2 tenths of an inch of rainfl will occur.

Expect fog to form early today across much of central and
southern PA as dewpoints continue to rise over the still
relatively cool ground.

&&

.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM SATURDAY/...
The waggling front should be north of the NY border and moving
north by sunrise on Friday. The clouds and fog around in the
morning will clear out very nicely from S-N, but it may take
until late afternoon in the north. It will be very warm and near
records again. We will start the day near 50 or better and go
with maxes in the 70s for most - and it is not out of the
question that someone in a southern valley urban area get to
80F.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Upper ridging over the east coast at the start of the period
will be temporarily squashed as a decent northern stream
shortwave moves east through the Ohio Valley and across the
Middle Atlantic states over the coming weekend. This will bring
a pronounced cold front across the region during the day
Saturday. Heights are forecast to rebuild across the eastern
half of the conus early next week on broad southwesterly flow
ahead of troffing developing over the Rockies.

The aforementioned cold front will return temps to near or
closer to near seasonal normals for Sunday into early next week.

Several shortwaves within the southwest flow aloft will bring
several weak fronts across the region next week. This will lead
to less than pristine sky conditions...but most of the time
period will be generally dry. However, enough low pressure
lurking at the surface could lead to a system of more
significance sometime during the week.

&&

.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
Isolated cluster of showers and thunderstorms near BFD.

Other storms and showers to the west, all the way into the
northern plains.

06Z TAFS sent.

Earlier discussion below.

A dying cold front will stall out at it pushes into northern Pa
this evening. Widely scattered showers have formed this evening
in the unstable air mass ahead of the front over central Pa.
These showers could produce a brief visibility reduction in a
few spots this evening. However, the bigger concern will come
after midnight, when radiational cooling leads to areas of low
CIGS/fog.

A plume of low level moisture ahead of the dying front,
combined with diminishing wind and radiational cooling, should
yield some late night fog. Latest SREF output indicating the
eastern half of the state will be most susceptible to a period
of IFR visibility early Fri morning. At BFD, a period of IFR
conditions appears likely late tonight, as frontal boundary
returns north as a warm front, accompanied by showers and low
CIGS.

Model soundings strongly indicating that any early VIS/CIG
reductions over northern and eastern Pa will give way to
widespread VFR conditions by late morning, as low level moisture
mixes out. Bufkit soundings indicate southerly winds will
increase during the late morning and afternoon, with gusts to
near 20kts.

Outlook...

Sat...AM fog/LLWS possible eastern Pa. Strong daytime FROPA,
accompanied by line of shra/tsra. Becoming windy late with
evening snow showers/reduced VIS possible at BFD/JST.

Sun...Windy.

Mon...Slight chance of light snow/reduced VIS northern Pa.

Tue...Showers/reduced CIGS possible, especially northwest Pa.

&&

.CLIMATE...
***February Warmth 2017*** Updated 2/22/17 at 8am EST

Record high temperatures for select sites for Feb. 23-24:
----------------------------------------------------------

Harrisburg 2/23: 70 in 1985
Harrisburg 2/24: 75 in 1985

Williamsport 2/23: 70 in 1985
Williamsport 2/24: 71 in 1985

Altoona 2/23: 66 in 1977
Altoona 2/24: 69 in 1985

Bradford 2/23: 57 in 1977
Bradford 2/24: 59 in 1961

-----------------------------------------------------------

Most 60 degree days in February at Harrisburg. Based on the
latest forecast, add 4 more days to the list and finish tied
for second with 7 days.

1. 10 days in 1976
2. 7 days in 1930
3. 5 days in 1991, 1943
5. 4 days in 1997, 1985, 1954, 1939
9. 3 days in 2017, 2016, 1996, 1990, 1961, 1932, 1890

------------------------------------------------------------

Warmest February on Record (Avg. Temperature through 2/21)

Harrisburg: 2017 rank=4 (38.6)
1. 40.4 in 1998
2. 39.6 in 1976
3. 39.4 in 1954

Williamsport: 2017 rank=4 (35.4)
1. 37.0 in 1998
2. 36.1 in 1954
3. 35.6 in 2002

Altoona: 2017 rank=2 (36.5)
1. 37.4 in 1976
Evening cooling will be a little slower than last
night.
Bradford: 2017 rank=6 (29.3)
1. 32.3 in 1998
2. 30.1 in 2002
3. 29.6 in 2012
4. 29.5 in 1990/1976
-------------------------------------------------------------

&&

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

&&

$$
SYNOPSIS...Dangelo/Lambert
NEAR TERM...DeVoir/Lambert
SHORT TERM...Dangelo
LONG TERM...Lambert/Gartner
AVIATION...Fitzgerald/Martin
CLIMATE...



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.