Area Forecast Discussion
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000 FXUS61 KPBZ 281844 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 244 PM EDT Sun Aug 28 2016 .SYNOPSIS... 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 ridge perimeter. && .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/...
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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.
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&& .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 Wednesday. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$

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