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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 211942

Area Forecast Discussion
National Weather Service State College PA
242 PM EST Thu Feb 21 2019

High pressure builds east into Pennsylvania from the issippi 
Valley over the next two days. A strengthening storm will track 
north through the Great Lakes this weekend, with a trailing cold
front coming through Pennsylvania Sunday.


A drier westerly flow has brought brightening skies and breezy
but milder conditions to the region this afternoon. Melting and
evaporating occurring as a result. Just a few stratocu evident
in the visible imagery over the Laurel Highlands but most areas
enjoying nearly full sunshine with temperatures ranging mostly 
through the 40s, except for upper 30s far north.

Sfc high pressure will build over lower MI tonight with dry cool
conditions prevailing over PA, while a flat wave of lower
pressure pushes moisture through the Virginias and to the mid
Atlantic coastline by 12z Fri. Expect a fair amount of mid and
high cloud to stream overhead, especially over the southern
tier. Mins will be seasonable with lows ranging from near 20F
northwest to the upper 20s southeast.


Fair weather continues Friday as high pressure and associated 
low pwat air mass build over the region. Still a fair amount of
cirrus streams across the region along axis of 120kt jet 
separating anomalous upper ridge over the Caribbean and a deep 
trough over the western conus. Thickest clouds will again be
over the south as flat wave exits off the mid Atlantic coast. 
A cooler afternoon expected, as mixing with be shallower 
beneath surface high, and am remaining close to Superblend/NBM 
highs in the upper 30s and low 40s.


Models typically do a better job with tracking and placing high 
pressure systems and this is again the case as a signifcant ridge 
will be negatively tilted across the Great lakes and  will continue 
to be pushed to the north east this weekend.

 A small but strong upper level low will undercut this ridge, 
driving a sfc system through the Mid Atlantic region this weekend. 
As has been the trend, warm air advection will track ahead of the 
system. 850 mb temperatures by 00Z Sunday will be in the 3-6C range. 
With daytime temperatures looking to be in the upper 30s to low 40s, 
and dewpoints in the low 30s, there seems to be less of a chance for 
FZRA however there could be localized pockets mainly over the higher 
terrain of the Appalachians. The trend aloft and and the surface 
continues to be warm, so rain will be dominate precipitation type. 

Focus then shifts toward the potential of strong winds Sunday
PM, as trailing cold front sweeps through the area, allowing
strong winds associated with Grt Lks storm to mix to ground
level. This scenario of a powerful low passing north of Pa fits
the pattern we see with our strongest winds across central Pa 
and a quick look at model 850mb winds suggest >50kt gusts are 
possible. Have introduced the possibility of strong winds in the

As the Temperatures continue to warm, expect a likely surge to 
springlike readings Sunday. The shallow cool air should mix out then 
there should be a return to seasonal readings for next week. Med 
range guidance points toward dry weather early next week, as high 
pressure builds across the region. However, model spread and 
forecast uncertainty ramps up by the middle of next week concerning 
the track, timing and strength of a fast moving shortwave 
approaching from the midwest. Given when the instability is for the 
storm next midweek, have changed precip type to mostly snow. 


VFR will prevail through Saturday with a drier and breezy west 
northwest wind (270-300 degrees gusting 20-25kts) throughout the
airspace slackening tonight. Isold MVFR cigs possible across 
the northwest airspace tonight/early Friday, otherwise VFR
expected to hold through Friday. 


Fri...MVFR cigs NW psbl early, otherwise VFR.

Sat...Trending MVFR to IFR with wintry mix to rain. 

Sun-Mon...Windy with sfc gusts 30-40kts from 250-300 degrees.




LONG TERM...Fitzgerald/Ceru