Area Forecast Discussion
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FXUS61 KPBZ 220535
Area Forecast Discussion
National Weather Service Pittsburgh PA
135 AM EDT FRI JUL 22 2016
Warm temperature, increased humidity, periodic thunderstorm
chances can be expected into early next week.
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
900pm update...convection to the northwest has all but dissipated
as the activity has run into a wall of stability and a capped
atmosphere. Would expect just additional cloud cover overnight.
Pops and temperatures have been updated.
Changes for the near term period included precip probability
adjustments for the potential that ongoing convection over the
Great Lakes Region survives mid level warmth, or spawns outflow
that ploughes into the diurnally destabilizing airmass over the
area. An escalation through "chance" numbers was thus included for
the evening hours, and maintained tonight basically north of
Interstate 70 as isolated to scattered convection may accompany
the actual shortwave. Limitations include the aforementioned CAPE-
robbing mid level warmth, fading diurnal support, and lack of
Morning lows in the moderating airmass were progged close to the
previous forecast, i.e. about 5 degrees above the averages.
.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/...
A better chance for rain is expected with another disturbance on
Friday. Improved boundary layer moisture and instability with a
marginally cooler mid level should be more conducive for showers
and storms, although limited deep layer shear should keep the
threat of severe isolated.
Thereafter, a shortwave ridge extending from the broad Central
CONUS high is forecast to continue the warmth and humidity over
the immediate area. Dewpoints in the upper 60s, to around 70 F
with temperature about 7 to 10 degrees above the averages will
generate heat indices in the 95 to 100 degree range for Saturday
and Sunday afternoons. A Hazardous Weather Outlook mention was
maintained for the Ohio counties as those heat indice projections
are flirting with the 100 degrees heat advisory criteria.
Convection in the warmth will be limited by warm mid levels and a
lack of forcing, so small PoPs will be the rule with hedges
dependent of weak disturbances and mesoscale effects.
.LONG TERM /MONDAY THROUGH THURSDAY/...
A stronger disturbance is forecast to carve the ridge over the
Upper Ohio early next week. That system will provide the next,
best chance of rain with a shortwave ridge quickly rebuilding in
its wake. The flatter flow pattern will moderate temperature in
this time frame, although readings are expected to remain above
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --VFR conditions are forecast in a prevailing sense through the TAF
period. Just high clouds are forecast for the rest of the night.
There is a small chance of shower or storm formation prior to 12Z
but not nearly enough to mention. There is a better chance of
storms during the day Friday but coverage looks scattered at best
with weak forcing. Handled with VCTS for now. Winds out of the
west and southwest should remain around 10 knots or less.
.OUTLOOK /FRIDAY NIGHT THROUGH TUESDAY/...
Restrictions will be possible late Sunday and Monday with
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