Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCTP 221119
Area Forecast Discussion
National Weather Service State College PA
719 AM EDT Wed Mar 22 2017
A parting shot of mid-winter cold today and tonight before a
more seasonable spring pattern returns temperatures to near or
above normal levels through the end of March. A wintry mix
remains possible early Friday morning before changing to rain.
The weekend starts off very mild with rain likely by Sunday.
.NEAR TERM /THROUGH TONIGHT/...
Minor changes made to the first 12 hours of the fcst based on
radar/satellite trends and observational data. Subsidence and
drying clearly evident with dewpoints in the single digits in SW
Cold/dry air continues to penetrate into Central PA behind
strong low level CAA via gusty NNW winds. Scattered snow showers
and flurries will continue early this morning across the
Northern Alleghenies with little to no accumulation expected.
The main sensible wx impact felt across Central PA today will
be the brisk cold especially relative to yesterday with 3/21 max
temps (~50-60F) and todays minimum wind chill (~0-20F) spread
on the order of 40 to 50 degrees!
The cold air is being supplied by a strong 1035+mb modified
arctic high pressure system that will drift across the Great
Lakes this afternoon to a position virtually overhead by
daybreak Thursday. The abnormally dry air coupled with clear
skies and light winds will result in a very cold night with
minimum temperatures falling to near-record territory. See the
climate section for 3/23 minimum temperatures records.
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
After a cold start, temperatures will begin to rebound as the
low level flow veers to the south/southwest. Highs Thursday will
be below average but it should feel warmer with very light winds
and plenty of late March sunshine.
WAA pattern ramps up quickly Thursday night into Friday via
anomalous west-southwest low level jet. Models continue to show
pcpn spreading into marginally cold/retreating and relatively
dry air near the surface between 06-12z Fri. Even with some evap
cooling/wet bulb effects, hard to see thermal profiles
supportive of snow unless the pcpn comes in very fast. Therefore
went with rain, sleet or freezing rain wx/ptypes which fits WPC
guidance. Ice accumulation will be hard to come by given temps
near 32F, warm surfaces and climo but will show a few hundredths
for storm total ice. Overall impact appears minimal but it only
takes a small amount of ice to cause problems especially during
the early morning commute. Temps should climb above freezing by
mid morning Friday ending the risk for ice.
Rain focus should shift north into NY Friday afternoon into
Friday night as baroclinic zones sets up in upper level
confluence zone downstream of deep cyclone moving through the
Southern Plains. The boundary placement will be key to the fcst
but it looks for now that most of the area will be in the mild
.LONG TERM /SATURDAY THROUGH TUESDAY/...
The models and ensembles continue to show a series of upper
troughs progressing onshore from the Eastern Pacific and across
the Southwest/South-Central Plains before deamplifying as they
move east of the MS River. The first of 3 upper troughs emerges
from the Southern Plains and crosses into the MS Valley Sunday
and continues to weaken as surface frontal wave translates
downstream crossing the OH Valley/Great Lakes into the northern
Mid Atlantic states by Monday. Blend of NBM/ECENS/WPC still
indicating max POPs in the Sunday-Sunday timeframe.
Above average temperatures are expected over the weekend with
the warmest day likely on Saturday with some sites approaching
70F over southern PA. Sunday should also be mild but a bit
cooler due to the likelihood of rain. Fcst issues pertaining to
a backdoor cold front appear to be confined to New England early
next week with temperatures remaining near or or above climate
averages into early next week.
.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --Decreasing snow showers with drier air working its way into
region. Gusty NW winds behind cold front for first half of the
day. VFR conditions into Thursday.
Thu...No sig wx expected.
Fri...Showers/reduced CIGS possible, mainly BFD.
Sat-Sun...Showers/reduced CIGS possible.
-- End Changed Discussion --
Minimum temperature records for 3/23 at select sites:
MDT: 14 in 1934
IPT: 8 in 1906
BFD: 5 in 1959
AOO: 15 in 1960