Area Forecast Discussion
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FXUS61 KPBZ 222208 AAA
AFDPBZ

Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
608 PM EDT Mon May 22 2017

.SYNOPSIS...
High pressure will provide a dry Tuesday with seasonal
temperatures. Unsettled weather for the remainder of the week.

&&

.NEAR TERM /THROUGH TUESDAY/...
610pm update...only change to the overnight period was an
increase in cloud cover. First cirrus cloud shield will exit to
the east this evening. This cloud deck will be quickly replaced
by a second area of cirrus clouds before dawn.

Previous discussion...
Diurnal clouds will go bye bye with sunset leaving passing mid
and high clouds the balance of the night. With good drying at
the surface courtesy of dewpoints in the lower 40s, this should
be enough to negate fog development outside of deeper West
Virginia gorges.

Any morning fog will burn off to what will be best weather day of
the week.  High pressure yields abundant sunshine with daytime fair
weather cumulus once temperatures climb into the mid and upper 60s
/convective threshold/.  West Virginia and western Maryland will see
more mid and high clouds creating a more pessimistic forecast.
Elected to keep a small pops for the higher terrain however, recent
runs have backed off on the amount of low level moisture thus QPF if
it happens will be a few hundredths as best.  The mercury will go a
few degrees beyond what was experienced today as H8 temps climb 2C
from today`s values equating to widespread lower and mid 70s for
maximum temps.

The bias corrected consensus raw guidance was used for max and min
temps.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
Anomalously deep mid level cyclone moves slowly east with
outer band of showers reaching parts of eastern Ohio by late
morning then taking its sweet old time before reaching western
Pennsylvania and northern West Virginia toward supper time. With
plenty of moisture in the column, do not expect to see any
convective activity as it moves through. Under heavy showers
due to the slow northward propagation and easterly wind
component /upslope/, far eastern areas may see rainfall amounts
approach an inch. Otherwise, look for a half inch less through
Wednesday night.

The occluded mature system oozes eastward Thursday with the
warm conveyor belt spreading more showers across the region
during the day. GFS is more optimistic than the NAM with the
plume of showers residing in central Pennsylvania and us under a
dry slot. With the difference being only a few hundred miles
and given the numerical NCEP suite struggles with these
systems, low confidence in the forecast for this time period,
however somewhere its going to rain so continued with likely
pops.

H5 low continues to move east Thursday night, however BUFR
soundings show still portray a lot of moisture so clouds will
hang tough. Wrap around showers will continue, but rain rates
won`t be as high.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Highlights:
- Active weather regime
- Temps right where they should be
- Memorial Day Weekend BBQ plans? Monitor forecast!

The weather pattern remains active right through the long term as a
series of system traverse the region making people dodge rain drops
this upcoming holiday weekend.  The long term starts out quiet with
a transitory surface anticyclone Friday, however that is quickly
shunted off to the east by an incoming mid level shortwave trough.
The aforementioned shortwave trough is slated to arrive Saturday
night into Sunday. Still timing differences as one would expect this
far out, but whenever it passes expect a several hour period of
showers and perhaps thunderstorms. Precipitable water peaks around
1.5" and with 30 to 40 kts of flow, therefore high water does not
appear a concern at this juncture.  Severe weather threat is low as
well given uncertainty with the timing.  If it passes during peak
heating hours, there would be a low threat for damaging winds. High
pressure builds is forecast to build in just time for Memorial Day.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
VFR at all airports through Tuesday. Light east winds are
forecasted through the period.

.Outlook...
The next chance for widespread restrictions and precipitation is
expected Wednesday night into Thursday.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&

$$



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