Area Forecast Discussion
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000 FXUS61 KPBZ 251735 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 135 PM EDT Sat Mar 25 2017 .SYNOPSIS... Well above normal temperatures will continue into next week. A few isolated showers are possible this afternoon but more widespread precipitation is expected later Sunday afternoon and evening. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... With noon update, only made slight changes to forecast. Many places had minimal increases in temperatures over the last hour, which is coincident with many automated stations now reporting overcast skies. Have stuck close to previous forecast high temps. Although nearly stationary front should make some southward progression during the day (current temperatures are 37 in Erie with a northwest wind and 63 in Meadville with a southwest wind), HRRR/RAP/NAM are all in good agreement that this afternoon/evening should remain dry across northern counties, so reduced coverage of showers and brought any chance pops down to slight chance. Previous discussion follows. With 915am update, primary update was to increase high temperatures by a couple of degrees today. It`s still quite early in the diurnal cycle to determine what temperature trends will be for today, but yesterday the high-resolution models did a much better job handling the well above normal temps, and so have decided to tweak the temperatures in that direction. Latest runs of the HRRR/RAP have forecasts very similar to yesterday`s observed highs. While temperatures this morning started much warmer than they did yesterday, more cloud cover is expected today as well. Cloud cover and ongoing warm advection supported a very warm night with temperatures 25 to 30 degrees above the averages. Morning hourly trends were tweaked toward the much warmer NAM and high res models in conjunction with current observations. Otherwise, shortwave ridging on the van of a cutoff Plains low suppresses will suppress widespread precip for most of the region. The exception may be the I 80 corridor where the encroachment of a front in conjunction with a northern stream shortwave may support some isolated, to scattered showers today. With the Upper Ohio firmly entrenched under the ridge/warm sector, warm high-temperatures can again be expected with readings about 20 degrees above the averages forecast, with only minor moderation projected along the I 80 counties as the aforementioned front sags toward/across that area. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... As the cutoff low over the Plains digs eastward this weekend, shortwave ridging will suppress widespread rain and maintain warmth for the immediate area. Moist flow and that systems occluded front will degrade that inhibition on Sunday and POPs will be on the increase, albeit with questionable timing given model discrepancy in handling the cutoff low. For now, have continued the ongoing categorical pops, but have adjusted timing and the mention of thunder given instability projections. Renewed shortwave ridging in the wake of that weakening system, and in advance of another midwestern shortwave in timed to provide a break in precip for Monday. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... Zonal and split flow is forecast to initially maintain above average temperature for the remainder of the week, although a midweek front is expected to drop them closer to the averages. The next, best chance for precip is expected with that front and with another, albeit filling cutoff low emerging from the Plains by the weekend. Tweaked Superblend was used in long-term forecast construction. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... Surface winds will veer over the course of the day as a front slowly transitions south over the region, however, VFR levels should largely be maintained. Outlook... Widespread restrictions are likely on Sunday with crossing low pressure, and again with a Monday night cold front. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...None. OH...None. PA...None. WV...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.