Area Forecast Discussion
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FXUS61 KPBZ 251326
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
926 AM EDT MON JUL 25 2016

.SYNOPSIS...
A slow moving cold front will pass through the area this evening
bringing the chance for scattered storms. A dry mid week before
the weather pattern gets active Friday and Saturday. Above normal
temperatures are forecast all week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The area is in a lull this morning with showers and thunderstorms
for now. The cold front out in Indiana will move east today and be
the focus for precipitation development. Latest hi-res models do
not indicate much in the way activity for our region. It appears
the thunderstorm complex over western NY will kick out an outflow
boundary and storms should develop southeast and move through
central PA. There is the possibility that our far northeastern
sections could see a storm that may approach severe limits. Much
the case on Sunday, wet microbursts and heavy rain will be the
primary impacts. Modified skew-ts illustrate a water loaded
sounding /pwats near two inches/ yielding potential for wet
microbursts. As for flash flooding, storm motion is 20-30 kts so
unless training develops do not foresee a widespread event.
Previous discussion below...

This would mean today`s convection will be very efficient rain
makers, allowing for a high risk for heavy downpours. Depending on
how much sunshine, and in turn surface heating occurs today, its
possible that some storms could approach severe levels. The main
threat would be strong winds. Models are showing different stories
on when and where convection may erupt, as they are attempting to
decipher the effects of the western complex and where its energy
will eventually travel. Since questions remain on location and
timing, have left pops in the chance category.

Temps were constructed using the Bias-Corrected short range
consensus.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
Front will fizzle out tonight and do little to eject the humid
airmass in place. Models are in pretty good agreement that any
convection will die out tonight. Noticeably drier air does move
in from the north in the mid and upper levels, however humidity
levels look to remain rather high through Tuesday with the lack of
low level dry advection.

It will take until Tuesday night and then finally into Wednesday,
when the juicy low level air is shoved to the south.

Both Tuesday and Wednesday look dry with a good deal of sunshine.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Highlights:
- Continued above normal temperatures
- Best shot at rain arrives Thursday night into Friday

Overall no real change to synoptic pattern for much of the week
as a broad H5 anticyclone dominates the southern 2/3rds of the
CONUS. Our mid level height values will fall a few decameters,
but not enough to usher in temps where they should be for this
time of year. Based on H8 temps progs...do not see a stretch of
90F+ weather like this weekend. However, would not be surprised
for eastern Ohio to be right around 90F for daytime highs most of
the week.

Baroclinic zone that crosses Monday night weakens and washes out
over the central Appalachians Tuesday as flow become parallel to
the boundary and it encounters increased subsidence. In its
wake, slightly cooler weather than what we have experienced
takes hold for mid week. By weeks end, another shortwave trough
traverses the region sweeping a cold front through. Timing
differences reside with ECMWF and GEFS, but ECMWF keeps the
recent summer trend going of shortwaves passing outside peak
heating hours. GFS opts for a Friday afternoon passage. Either
way, the next shot of widespread precipitation appears to be
Thursday night into Friday. Zonal flow re-establishes for the
weekend with temperatures near the climo average of lower to mid
80s.

&&

.AVIATION /13Z MONDAY THROUGH FRIDAY/...
General VFR expected today in the warm, moist airmass ahead of an
approaching front. A few showers have popped up across the region
this morning, but they have missed the terminals to this point.
Expect coverage to increase as we become more unstable this
afternoon but with no definite line of showers and storms
developing, have opted to carry VCTS in the TAFs. Restrictions
will be limited to any terminal that experiences a thunderstorm.

The rather diffuse front will slowly sag across the region through
this evening, with a wind shift from southwest to west.

.OUTLOOK /MONDAY NIGHT THROUGH FRIDAY/...
Lingering low level moisture tonight may promote restrictions in
fog. But after Tuesday morning, the next chance for restrictions
will be with a late week front.

&&

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

&&

$$

synopsis...98
near term...98/33
aviation...34



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