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FXUS61 KPBZ 261758

Area Forecast Discussion
National Weather Service Pittsburgh PA
158 PM EDT Sun Mar 26 2017

Warm temperatures will be marred by rain this afternoon and 
Tuesday as a series of low pressure areas cross the region. A 
Tuesday cold front will drop readings back toward the averages.


With noon update, tweaked pops for rain moving into eastern
Ohio, as well as rain across central West Virginia that will
move northeast into the region. Also tweaked temperatures a bit
in locations that received a few hours of sun earlier. General
trend of forecast appears to be on track. Previous discussion

The primary change with the 8:30am forecast update was to slow
down arrival of precipitation by a couple of hours in most
locations. Closest precipitation remains west of the Columbus
metro area, and trended the forecast in the direction of the
HRRR/RAP. Only minimal changes made to the rest of the forecast.

Shortwave ridging in advance of midwestern low pressure continues
to suppress precip over the Upper Ohio Region despite the presence
of a stalled front analyzed across the Pittsburgh area.

That situation will change today as the low is forecast to continue
digging eastward, escalating POPs from the west as the system 
trundles toward the Lakes. A general half, to three quarters of
an inch of rainfall is expected with the passage, and in the
wake of the systems occluded front during the next 24 hours.

Thunderstorm formation is progged to be hampered by meager
instability, although deep layer shear will be favorable for
severe as usual this time of year with the crossing low. A
chance thunder mention was maintained with the categorical rain

Rain chances will fade quickly on Monday morning as the weakening
trough slides eastward. Given the occluded nature of the front,
warm temperatures will be maintained in its wake.


Shortwave ridging is timed to keep much of Monday dry, but
another midwestern trough, albeit weaker is likely to generate 
more precip on Monday night and Tuesday. That system is 
projected to pull a cold front across the region later on 
Tuesday which will drop temperatures closer to the seasonal 


With high pressure settling in behind Tuesday's cold front and
northerly flow developing, dry and seasonable weather is
expected Tuesday night through Thursday. By Thursday evening, 
the GFS and ECMWF begin to show diverging forecasts, with one 
model showing low pressure over Lake Huron by Saturday morning 
and the other model showing low pressure across Tennessee. Have 
stuck close to the Superblend through this part of the forecast.


Low pressure tracking across the OH valley/lower Great Lakes 
will result in 3 distinct periods of showers the remainder of
the afternoon and tonight. VFR looks more likely to be
maintained after the first wave...but as moisture increases in
the lower levels deterioration to low MVFR is likely.
Thunderstorms still remain a possibility, however, have not been 
included in TAFs at this time based on limited instability.

Restrictions are likely again Mon night/Tue with a crossing 
cold front.



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