Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Pittsburgh PA
625 am EDT Friday Oct 9 2015
a cold front will bring showers today followed by cooler
temperatures for Saturday. Dry and mild Sunday and Columbus day.
Near term /through tonight/...
cold front approaching Northwest Ohio at 09z. Have adjusted probability of precipitation
to current radar trends as pre-frontal shower bands have developed
across northwest PA and also no moving into the southeast ridges.
Also lightning strikes across northern PA currently and have
expanded thunder mention. Remainder of forecast unchanged and
previous discussion follows.
Front will sweep across the region today with increasing showers
this morning...then showers and a chance of thunderstorms this
afternoon. Have trimmed probability of precipitation slightly across eastern Ohio into the
northern West Virginia Panhandle as best moisture and lift with
front trends across I-80 and from Pittsburgh east. Any
thunderstorms not expected to be widespread or strong with weak
cape near 500j/kg...although bulk shear will be close to 40 kts.
00z models in agreement in being a bit quicker to push front
southeast this evening and have trended a quicker end to precipitation
with most locations dry by 00z. The exception would be the far
southeast ridges where scattered showers will end before midnight.
Warm advection ahead of front will keep temperatures in the 60s
north of I-70 and in the ridges...with lowers 70s south. After
showers end this evening drier and cooler as high pressure builds
across the region. Lows in the lower to middle 40s. Temperatures were
a blend of met/mav MOS.
Short term /Saturday through Monday/...
cool northerly flow will keep temperatures below the seasonal
averages on Saturday before warming on Sunday as surface high
shifts east and southwest low level flow returns. Generally stayed
close to bias corrected MOS values for the weekend. Warmer still
for Monday in warm advection ahead of an approaching cold
front...with high clouds increasing late.
Long term /Monday night through Thursday/...
after the passage of an initial shortwave and frontal boundary
Monday night...broad upper troughing is prognosticated across much of the
eastern Continental U.S. Through the upcoming week resulting in seasonally cool
temperatures. Maintained shower chances Monday night...though the
best upper support for precipitation is prognosticated to stay north of the area
for the rest of the week as weak shortwaves advance through the main
trough. Followed close to wpc ensemble based guidance to smooth out
minimal model differences through the period.
Aviation /10z Friday through Tuesday/...
condition deterioration to MVFR is expected by middle morning as an
approaching cold front brings showers to the region. With limited
instability...a thunderstorm is possible but chances appear too
low for taf inclusion. The front should complete it/S passage this
afternoon/early evening...with a wind shift from SW to northwest. MVFR
stratocu ceilings should continue behind the front tonight.
Outlook...Saturday through Tuesday...
brief restriction chances return with a Monday night cold front.