Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
757 am EDT Monday Mar 10 2014
a crossing disturbance will bring clouds and a few sprinkles
today. Low pressure will track across the upper Ohio Valley region
Tuesday night into Wednesday evening bringing rain and snow.
Near term /through tonight/...
a weak shortwave will cross the region today bringing clouds. Precipitation on radar
appears to be aloft as no surface observation stations are repeating any precipitation. Later
this morning we could see a few sprinkles reaching the ground but
measureable precipitation is not expd. Temperatures should rtn to above average readings
Previous disc...high pressure may nose in from the south
overnight. Wind speeds will remain up overnight...and with skies
only partially clearing...think that tonight could be rather warm.
While locations north of the Pennsylvania Turnpike that may still
have some snow cover should drop towards the freezing mark...rest
of the region is expected to only drop into the lower 40s.
Short term /Tuesday through Wednesday night/...
a frontal boundary will sag across the Great Lakes
Tuesday...arriving locally Tuesday evening. While some light
precipitation will be possible along the front Tuesday
night...more substantial precipitation is not expected until late
Tuesday night into Wednesday as low pressure advances along the
front. Low pressure system will move quickly...passing from
Kentucky Wednesday morning to the New Jersey coast by Wednesday
evening. Bulk of precipitation will fall Wednesday...with precipitation
rapidly diminishing from west to east Wednesday evening.
There are still plenty of details that will bring changes
to the forecast. 00z models have trended slightly colder...which
should allow precipitation in most locations to change from rain
to snow slightly quicker. Coupled jet is most apparent in 00z
NAM...although GFS and European model (ecmwf) both showed this signature to a
lesser extent. Current timing suggests highest rates could occur
as precipitation is generally changing from rain to snow in the
early afternoon. Warmer air aloft could also allow for a brief
period of freezing rain. Overall...feel that southernmost
locations could pick up around an inch of wet snow during the
late afternoon and evening hours...while locations along the
Interstate 80 corridor could pick up several inches of snow
depending on just how long it takes for precipitation to change
from rain to snow in the morning. Will add mention of the storm in
the hazardous weather outlook but do not have enough confidence in
any given scenario to issue a Winter Storm Watch.
Much colder air will move in behind the low pressure system
Wednesday night...and temperatures will take a tumble all the way
into the single digits up north and lower teens elsewhere.
Long term /Thursday through Sunday/...
high pressure will quickly build in Thursday. Cold air wont linger
long as strong warm air advection kicks in by Thursday evening as a weak system
approaches from the northwest. The colder than average temperatures Thursday will give
way to slightly warmer than average temperatures Friday before another...weak
cold front pushes through in the early portion of the weekend.
Timing of the front remains in question as models have sped up the
feature significantly from earlier runs. Colder air lingers
through the weekend as a broad trough remains entrenched over eastern
Aviation /12z Monday through Friday/...
a weak disturbance may bring a brief shower this morning...but
primarily thicker cloud cover. Still expecting mostly VFR through
Monday with gusty SW winds developing. Clouds dissipate Monday afternoon and
evening. Low level moisture could generate some borderline MVFR
stratus for eastern terminals overnight.
Outlook.../Monday night through Friday/...
widespread restrictions are expected Tuesday night into Wednesday evening as
low pressure tracks across the upper Ohio Valley.
through Wednesday...the breezy combination of warmth with incrsg
dewpoints followed by rain will eliminate any remaining snow in the
ridges. With the quantitative precipitation forecast of the Wednesday system on the order of
three quarters to an inch...flooding concerns should be
local...however...ridge zone creeks and the Monongahela river
basins will have to be monitored as the remaining water equivalent is