Area Forecast Discussion
Issued by NWS
FXUS61 KPBZ 200237
Area Forecast Discussion
National Weather Service Pittsburgh PA
937 PM EST Thu Jan 19 2017
Rain will return to the region late tonight and Friday as the
next upper level system moves through. The mild pattern continues
through the weekend.
.NEAR TERM /THROUGH FRIDAY/...
Plume of moisture and lift associated with approaching shortwave
and warm front will provide for a period of rain across the
region overnight into Friday. With good model consensus, have
made very little change to the PoP forecast. Only adjusted the
timing slightly based on the latest hi res model guidance with a
period. While temperatures have fallen off a bit with the help of
some clearing/thin cirrus, this should be stifled as thicker
clouds spread northward. Also, while some of the observations in
these areas are now near freezing, these values are likely to warm
before precipitation occurs, especially as the rain encroaches on
the dry air that is currently present in the 00z PBZ sounding.
Rain will shift northeastward Friday afternoon, with above
average temperatures expected, despite persistent cloud cover.
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
Although different models show isolated showers through this
period, have decided to go with a dry forecast Friday night and
Saturday, and chance pops Saturday night since there should not be
much to provide any sort of organized lift. This should be the
warmest stretch of the forecast, with lows only dropping into the
40s and many locations reaching the 60s on Saturday.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
A strong upper low will develop over the Southern Plains Sunday and
track eastward into early Monday, before turning toward the
northeast Monday night and Tuesday. While the GFS and ECMWF keep
the surface low moving along the Atlantic coastline, the NAM keeps
the surface low as far west as Kentucky, and have not used the NAM
during the early part of the extended forecast. The GFS and ECMWF
are trending farther east with the track of the system, and while
they are in good agreement, this track may result in the
widespread precipitation shield also being farther to the east.
Nevertheless, have still kept likely pops in the forecast for now
from Sunday through Monday night. After a brief break in
precipitation Tuesday, GFS and ECMWF are in good agreement showing
low pressure moving across the Great Lakes Wednesday and Thursday,
and have gone with chance pops. Although temperatures will be
lower with multiple storm systems, the forecast remains well above
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Clouds continue to erode westward this eve. A period of VFR will
prevail at most, if not all, of the sites where this has occurred,
with low clouds unlikely to return until the precipitation reaches
the region in the early morning. After this time, conditions
should return to low mvfr/ifr with the passage of the shortwave
and a deep inversion likely to keep low clouds overhead until the
Wind will be ese, gradually veering to wsw as the day progresses.
A brief period of LLWS is possible as wind just above the surface
will just meet criteria.
Restrictions are likely to continue through Friday night with the
passage of low pressure, and will return again on Sunday with the
approach of another system.