491
FXUS61 KPBZ 141117
AFDPBZ

Area Forecast Discussion
National Weather Service Pittsburgh PA
717 AM EDT Wed Aug 14 2024

.SYNOPSIS...
Dry weather with slowly rising temperature is expected through
Thursday. Precipitation chances will increase Friday as a front
slowly crosses the region. A more active pattern is possible for
the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
KEY MESSAGES:

- Dry and comfortable with temperatures near normal.

-------------------------------------------------------------------

The eastern trough, which has brought the quiet weather pattern
to the region, will slowly shift eastward today. The trough is
being displaced by an amplifying ridge that will build into the
Midwest. With the shifting of the upper level waves, slow
height rises are anticipated today. This will mean a
continuation of the dry weather and warmer temperatures. We may
not see as much CU develop this afternoon due to the warm air
advection aloft.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
KEY MESSAGES:

- Dry weather with slowly rising temperature expected
  Thursday.
- Shower/storms chances increases Friday, but timing issues
  still remain.

-------------------------------------------------------------------

Upper level height rises will continue on Thursday as the ridge
axis moves into western Ohio during the afternoon. The rises
will be somewhat shunted later Thursday as a shortwave trough
will swing through the western Great Lakes and begin to flatten
the eastward moving ridge. The biggest impact from the wave will
be an increase in high clouds. Warmer air will continue to
overspread the region, so temperatures will warm a few degrees
above normal.

Timing differences remain on the progression of the trough
moving across the Midwest Friday morning and the corresponding
surface front. Models are promoting a stacked system over the
western Great Lakes Friday with a lobe of upper level energy
swinging eastward on the southern side of the 500mb low. A
warm front will press eastward with the energy aloft and cross
the region sometime on Friday. Again, still seeing timing
differences with the eastward progression. Latest model
solutions are not showing a lot of instability or shear, and a
slower progression would allow more cloud cover to spread across
the region ahead of the rain. Temperatures aloft remain
relatively warm, with model soundings showing a capped
atmosphere for a time on Friday. Friday does look like a good
shot at widespread rain, but there is still much to be resolved
with the threat for convection.

Temperatures will cool a bit on Friday with increased cloud
cover and rain.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
KEY MESSAGES:

- The threat for rain continues into Saturday with slow passage
  of a cold front.
- Ensembles favor Great Lakes troughing into early next week
  that would maintain low probability, diurnally driven
  convection.
-------------------------------------------------------------------

Ensemble synoptic pattern analysis shows relatively minor
differences of the progression of an upper level trough towards
the Great Lake region into early next week. Broadly speaking,
this pattern will promote periodic shower and thunderstorm
chances, low probability severe/flash flood threats, and near to
slightly below average temperature.

More convective development is possible Saturday as the upper
trough positions just west of the area and both the pre-frontal
trough and surface cold front swing through. Ensemble means
hint at some marginal instability with dry air aloft leading to
a low end wind threat Saturday afternoon, but confidence is
still low on conditions all aligning properly.

Sunday into Monday is likely to feature isolated to scattered
diurnally driven convection with the backside of the trough
remaining overhead.

&&

.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
Surface high pressure will promote light NE wind and VFR
conditions through the TAF period. Diurnal heating may spark a
few to locally scattered CU this afternoon.

Very localized river valley fog may develop between 06z-12z
Thursday morning near FKL.

.Outlook...
High confidence exists for VFR through Thursday under the
influence of high pressure. A slow moving upper level trough
will promote periodic showers and thunderstorms with occasional
restrictions Friday through Monday. Probabilities for
restrictions peak Saturday morning with MVFR (40-70%) to
localized IFR (20-50%) cigs.

&&

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

&&

$$

SYNOPSIS...22/Frazier
NEAR TERM...22
SHORT TERM...22
LONG TERM...22/Frazier
AVIATION...Frazier