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NWS Area Weather Forecast Discussion
County Warning Area [CWA]: PBZ
Regional NWS Weather Office: Pittsburgh, PA

FXUS61 KPBZ 222341

Area Forecast Discussion
National Weather Service Pittsburgh PA
641 PM EST Thu Feb 22 2018

Periodic rain chances will continue through Sunday. Conditions
should be dry for the beginning of the work week.


Deeper moisture is exiting the southeastern portions of the
area at the moment, but easterly flow is well entrenched over
the area, and cold air is oozing down through central
Pennsylvania toward the Mason-Dixon line in the higher terrain
fairly efficiently. However, above the boundary layer, flow
quickly turns southwesterly with warm advection. As this occurs,
surface temperatures will continue to fall on the eastern
periphery of the forecast area. This will not really be
problematic anywhere in the area except for one lone
exception...Garrett County, Maryland.

In Garrett County, NAM/NAM 4 km nest projections seem to be
handling the boundary layer and the layers below 925 mb far
better than other guidance. In fact, they are the only pieces of
guidance that both show some semblance of an idea with regard to
surface temperatures and follow what is the observed temperature
persistence pattern based upon boundary layer flow. That said,
temperature fall down toward and essentially straddle freezing
from later this evening through Friday morning in the interior,
eastern, and northern portions of the county. Model soundings
suggest +10C above that level, so the cold air will be
exceedingly shallow. Thus, any precipitation that falls will be
either rain or freezing rain. With that in mind, a winter
weather advisory has been issued for this interval for Garrett
County alone. All other mountain zones should remain above
freezing. In fact, based upon the thermal profile, the majority
of Tucker County should remain within striking distance of 50F
most of the night. This is due to the fact that low level ESE
flow that turns SE does not favor cold air sneaking into that
area. Fries

Previous discussion follow for Friday...The focus of rainfall
on Friday will be along a warm front moving into the region from
the west. Many locations could pick up at least an inch of
rainfall during the daytime hours, which was enough to cause
flooding issues today. The additional waves of rainfall expected
Friday and Saturday are the primary reason that earlier today
the flood watch was extended to all locations through the end of
the weekend. Southerly winds will allow for very mild
temperatures tomorrow, with highs reaching the 50s and 60s, with
an isolated 70 degree reading not out of the question.


The second 24 hour period of the forecast should be very similar
to the first 24 hour period of the forecast, with a break in
precipitation Friday night and reintensification on Saturday.
However, Saturday night will remain wet as the region will be in
a transition area from warm front impacts to cold front impacts.
The cold front will push through on Sunday, bringing some
definitive clearing to the region. Highs will reach the 50s and
60s again before the cold front arrives.


The work week should start out dry before a large system moves
from the Plains towards the East Coast Wednesday into Thursday.
Temperatures will be slightly above normal.


MVFR/local IFR stratus is expected to continue tonight with low
level moisture below a temperature inversion. Widespread IFR and
rain is expected again late tonight and Friday as another area
of low pressure crosses and lifts a warm front, then a cold
front, across the area. With the crossing sfc boundaries, winds
should veer through the period.

Restrictions are expected to continue with a Saturday warm
front, and a Sunday cold front.


Numerous forecast points are already at action stages across the
region. Pittsburgh is already over 21 feet.

3 successive disturbances over the next 72 hours will drop
rainfall amounts ranging from 1.50 to 4.50 inches across the

River Flood watches will likely be expanded across the region.
With QPF, we expect river flooding to be widespread by 00Z/25


MD...Flood Watch through Sunday evening for MDZ001.
     Winter Weather Advisory until 10 AM EST Friday for MDZ001.
OH...Flood Watch through Sunday evening for OHZ039>041-048>050-
PA...Flood Watch through Sunday evening for PAZ007>009-013>016-
WV...Flood Watch through Sunday evening for WVZ001>004-012-021-



Forecast Discussion from: NOAA-NWS Script developed by: El Dorado Weather