Area Forecast Discussion
Issued by NWS -- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KPBZ 281844
Area Forecast Discussion
National Weather Service Pittsburgh PA
244 PM EDT Sun Aug 28 2016
Thunderstorm chances will increase today as warmth and humidity
fuel a crossing disturbance.
.NEAR TERM /THROUGH TONIGHT/...
Weak boundary will sink across the region through the period. A
few showers have already popped up in northern PA but consensus is
that coverage will increase this afternoon as we destabilize.
Most, if not all of the model guidance suggests greatest
thunderstorm chances will be north of I-70 supplemented by the
passage of a shortwave and very minimal cooling aloft. Steep low
level lapse rates would suggest some storms may produce strong
wind gusts through the evening, if they can maintain themselves.
With more cloud cover and thunderstorm development, temperatures
may be a degree cooler than yesterday. However, humidity levels
will be higher, maintaining the mid 90 heat indices.
Convection should fade with the loss of heating, but low chance
PoPs were maintained as shortwave energy extending from Canadian
low pressure is progged to continue carving the aforementioned
.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
Low pressure is forecast to dig over Eastern Canada, with trough
extension over the Northeast U.S. by Monday morning. The
associated surface front may continue to provide focus for
diurnally-enhanced convection over southern zones on Monday, but
building surface high under northwest flow should suppress precip
by Tuesday. The POP forecast has been adjusted for that
eventuality, and for small rain potential with the reinforcing
front on Wednesday.
Short term temperature will be in decline as an Eastern CONUS
trough develops. These were forecast near, or a couple degrees
under the averages using SuperBlend guidance.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
-- Changed Discussion --Troughing over the eastern CONUS will result in cooler
temperatures the remainder of the week before ridging builds back
in this weekend. Dry conditions are forecast under dry
northwesterly flow and ridging later in the period.
-- End Changed Discussion --
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Warm air aloft has been capping off convective development thus
far, however, weak surface convergence, slightly cooler
temperatures aloft, and the passage of a weak wave in the mid and
upper levels looks more likely than not enough to trigger
convection by late afternoon into early evening. Outflows from
early convection should be deep enough to continue initiate storms
from northwest to southeast heading into early evening but will
diminish as instability lessens. Do to the degree of uncertainty
in timing have opted to utilize mention of VCTS in latest TAFs
but will update as details emerge through the afternoon.
.OUTLOOK /MONDAY THROUGH THURSDAY/...
Restrictions are possible Monday mainly S of PIT as the front
completes its passage, and again with another crossing front