Scientific Forecaster Discussion
Area forecast discussion
National Weather Service State College PA
839 am EDT Wednesday Oct 7 2015
high pressure will dominate the weather pattern through Thursday
with mainly dry conditions and temperatures averaging near to
above normal. A low pressure system moving from the Great Lakes
through New England will drag a cold front across central PA and
bring rain showers on Friday. High pressure will regain control
of the weather pattern and return fair and dry conditions for the
Near term /through tonight/...
infrared satellite loop shows low clouds advancing east through the
susq valley as surface trough becomes progressive ahead of a cold front
across the Great Lakes. Partial clearing developing across central
and western sections will continue and expand statewide by late
A broad/flat upper trough tracking eastward along the northern Great Lakes
today will send a weak cold front /currently analyzed over central
lower Michigan/ across the County Warning Area by the end of the period. An overall dearth
of forcing and decreasing moisture suggest a dry frontal passage despite very
light model quantitative precipitation forecast mainly focused over the northwest alleghenies. Precipitable water values
actually peak early this morning prior to 12z and trend lower
through tonight...therefore will maintain dry forecast with consensus
odds of measurable precipitation quite low/10 percent or less. Despite a good
bit of cloud cover early in the day...a mix of clouds and sun
later this afternoon should allow highs to peak a few to several
degrees above early October climatology. Expect some clearing tonight as
high pressure migrates eastward from the upper Midwest into southern Quebec.
Short term /Thursday through Friday night/...
departing surface ridge is quickly overrun by robust warm air/Theta-E
advection pattern spreading eastward ahead of quick moving low pressure
system tracking from the upper Midwest through the lower Great
Lakes and northeast states. Anomalous precipitable waters and moisture flux
values focused into the area via 30+kt southwesterly low level jet ahead of the
trailing cold front...combined with modest height falls/decent
uvm will continue to support a high likelihood to near certain
odds of rain showers on Friday. Sufficient instability may also
lead to a few thunderstorms across the south central and southeastern parts of the
County Warning Area during the afternoon. The Storm Prediction Center day 3 marginal risk clips this area /from
Fulton County to Lancaster County/ and have included possible
wind/hail threat in severe weather potential statement. Quantitative precipitation forecast amounts between 0.25 to 0.50 inch basin
average will be limited to some extent by duration as the frontal
band shifts steadily southeastward into Friday night.
Long term /Saturday through Tuesday/...
07/00z GFS and European model (ecmwf) are in better agreement this cycle...indicating
a drying trend from north to south early Saturday. Kept low probability of precipitation
prior to midday in the far south /which may still be overdone/
before going dry for the remainder of the day. Saturday will be
the coolest day out of the next 7 with daytime highs in the middle
50s to lower 60s and nighttime lows in the u30s to m40s.
The global models and ensembles continue to indicate a brisk west
to northwest flow aloft extending along the Canadian border into
the northeast next week. Retrogression of the West Texas trough to
off the Pacific coast of Mexico appears to allow for broad
troughiness to develop/persist east of The Rockies...with lead
shortwave energy closing off in vicinity of the Carolina/Georgia coast this
weekend...followed by a second northern stream wave and surface cold front
reaching the Appalachians by next tues/dy7. After bottoming on
Saturday...expect temperatures to moderate with seasonably mild readings
through Tuesday with a slight cool down possible midweek.
Aviation /13z Wednesday through Sunday/...
no large changes made to 12z tafs.
Most of the day on Tuesday featured decent conditions. There was
a period of time with MVFR ceilings. This is the case at the
current time...with the lowest ceilings across the north.
Anyway...still MVFR and at times IFR ceilings across the region.
Not much fog...given the cloud cover.
Cold front is still well northwest of PA...over Michigan.
Expect conditions to improve by late morning or early
after...as a weak cold front moves south of the area later today.
Did put some fog in again for later tonight...as skies clear and
winds drop off.
Again...expect all terminals will improve to VFR by late
morning or early afternoon.
High pressure will build southward from Quebec on Thursday.
Thursday...patchy am fog possible.
Friday...showers/MVFR ceilings poss.
Sat-sun...no sig weather expected.