Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
844 am EDT Wednesday Apr 1 2015
dry weather today will be followed by a warm Thursday with
increasing shower and thunderstorm chances.
Near term /until 6 PM this evening/...
845 am...no major changes other than to tweak hourly trends.
Forecast looks good overall.
a weak shortwave is prognosticated to cross the region this morning bringing
an increase in clouds...especially north of pit. Otherwise...surface
high pressure should bring dry weather today with any remaining
clouds decreasing during the afternoon. Near average highs are
expected using the latest bias corrected MOS.
Short term /6 PM this evening through Saturday/...
warm advection is expected tonight and Thursday in southwest flow
ahead of the next approaching shortwave. This wave and its
associated cold front is prognosticated to advance across the region late
Thursday with increasing shower chances. Limited instability is
prognosticated...but with a low level jet in place and showalter indicies
just below zero...maintained the chance of thunder. The front is
prognosticated to stall across the area through Friday as a surface wave
develops and tracks along it...with periods of showers continuing.
With the rain prognosticated to be spread out over a couple of days...
significant problems are not expected at this time.
The upper trough axis is prognosticated to shift east of the area Saturday
morning...with the front and surface wave exiting. A brief
changeover to snow is possible as the precipitation ends. Any remaining
precipitation chances...mainly NE of pit...should diminish by afternoon.
Generally followed a NAM/sref/GFS blend for forecast details.
Discounted European model (ecmwf)/S stronger surface wave with the lack of a strong
digging upper trough. A blend of sref and MOS data was used for
the temperature forecast...resulting in readings around 15 degrees above
average for Thursday in gusty SW winds...with a decrease to below
average levels again by Saturday.
Long term /Saturday night through Tuesday/...
a trailing shortwave is still prognosticated to generate some showers
along a southward sagging cold front on Sunday. Confidence in the
situation...especially southward progress of the front remains
questionable...so slight...to chance probability of precipitation were confined to
Otherwise...temperatures are expected to moderate to near...then above
the seasonal averages as a shortwave ridge develops over the
eastern half of the Continental U.S. In response to western states troughing.
Precipitation chances will rise as the week and trough progress.
The long term prognosis was primarily based on adjusted wpc
Aviation /13z Wednesday through Sunday/...
general VFR is expected to continue at most ports despite passage
of a weak shortwave today. The exception may be at fkl and duj
where some early local stratus and MVFR stratocu are possible
with that feature. Otherwise...only middle level cloudiness will Mar
Outlook.../Thursday through Sunday/...
restrictions are likely as a frontal system brings showers...and a
few thunderstorms to the area later Thursday...and into Saturday.