Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service State College PA
1155 PM EDT Wednesday Apr 16 2014

Synopsis...
high pressure will drift northeast of the region tonight...
supplying US with another very cold night for middle April.
Temperatures will gradually rebound tomorrow and Friday as the
flow around the retreating high becomes southeasterly. Easter
weekend looks mainly dry but cooler than normal.

&&

Near term /until 6 am Thursday morning/...
high pressure will continue to retreat off to our
north...providing clear to scattered skies and light winds
overnight. Temperatures will settle to near...or perhaps slightly below
record lows. See climatology section below for more details.

A freeze warning has been posted for the lower susq valley region
from midnight - 8 am Thursday.

&&

Short term /6 am Thursday morning through 6 PM Thursday/...
high pressure will have drifted into the New England states by
midday Thursday. In its wake...low level southeasterly flow beneath deep south
to south-southwest flow aloft will help temperatures to recover to more bearable
levels for middle April...but still 5-7f shy of normal afternoon
highs.

Some scattered pancake cumulus is likely Thursday...along with some
periods of cirrus or high Alto cumulus.

After a frosty morning with a light easterly wind...the wind
should increase from the southeast to 8-12 kts...and gust into the
15-19kt range in the afternoon which will still make it feel on
the chilly side.

&&

Long term /Thursday night through Wednesday/...
high pressure will strengthen to +3-4sd over northern New England
through Thursday...before slowly weakening into the upcoming
weekend. This suggests a possible easterly maritime low level flow with
low clouds and perhaps some light rain/dz possibly reaching into the
southeastern/scentral zones. At the very least...the surface pressure ridging
east of the Appalachians will limit blyr mixing and - when
factoring in the east-southeast winds - will keep temperatures cooler in the
eastern zones Thu/Fri.

There is general agreement in a shortwave trough crossing the
Great Lakes region Friday night-Sat am with the best chance for light/scattered
rain showers over the northwest 1/3 of the County Warning Area. The models generally
agree on this idea...with previous timing diffs mostly resolved.

Looking into the medium range...while forecast confidence in the precipitation
pattern is average at best the guidance favors a mainly dry forecast sun-
Monday before rain chances return by Tuesday. The uncertainty is
associated with a low amplitude Pacific shortwave trough ejecting
eastward from the northern rockies. The generally weak nature of
the Pacific energy crossing the northern-tier Continental U.S. Along with a
somewhat unusual but rather explicit north-south split in the
500mb flow both contribute to low confidence in the forecast.

The split flow aloft appears to be short-lived as the lw pattern
is forecast to reamplify by the middle of next week...with strong
height falls/Spring cut-off low prognosticated to migrate from the West
Coast into the Great Basin...supporting slightly above-average 500mb
ridging spreading eastward from the plains to the Midwest and
eventually into the northeast toward the end of next week. A
Canadian shortwave crossing northern New England may delay the
height rises in the east and send a back-door cold front into the
middle-Atlantic around day 8.

Overall...expect temperatures to moderate from below normal to
near or slightly above late April normals by next Wednesday.
Opportunities for rain now appear to be focused in the Friday night
Saturday morning and Tuesday time-frames. So most of the Easter
weekend looks like it will be mainly dry in central PA.

&&

Aviation /04z Thursday through Monday/...
calm winds and clearing skies will be the norm overnight. VFR
will continue through Thursday...though southeast winds will
increase to 8-12 kts with occasional gusts in the upper teens to
low 20 knots range tomorrow...before subsiding tomorrow early
evening.

Another round of wet weather possible by Sat.

Outlook...
Friday...generally VFR. Areas of MVFR ceilings possible across southeastern Penn
early Friday.
Sat...reduced ceilings/visibilities in rain /and possibly some wet snow
across the higher terrain/.
Sun and Monday...mainly VFR under a weak ridge of high pressure.

&&

Climate...
looks like Bradford has a new record min for the 16th already -
and also came close for the 15th as well - just a degree off tying
the record for tax day. But the short period of record at bfd
Airport /since 1957/ makes it a little easier to crack many of the
records there. Kjst and kaoo have also attained/tied their
respective record mins for today.

Temperatures again Thursday morning - will be close to record
lows. Below are the current records for April 17th from around
the area.

Aoo... 23/1980
bfd... 16/1963
jst... 21/1966
ipt... 25/1904
MDT... 29/1980 and 1904

&&

Ctp watches/warnings/advisories...
freeze warning until 8 am EDT Thursday for paz057-059-063>066.

&&

$$
Synopsis...la corte
near term...la corte
short term...dangelo/Lambert
long term...steinbugl
aviation...Lambert/ceru
climate...