Scientific Forecaster Discussion
000 FXUS61 KPBZ 232349 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 749 PM EDT Fri Jun 23 2017 .SYNOPSIS... A cold front sweeping through early Saturday will return comfortable humidity levels by the weekend. Below normal temperatures greet us early next week. && .NEAR TERM /THROUGH SATURDAY/... Tweaked forecast to reflect current radar trends. The heaviest rain rates appear to be over with. We will be conducing a damage survey for Greene and Fayette counties Saturday and likely into West Virginia. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... Dry and less humid air will be welcome news for many this weekend as dewpoints drop into the 50s! Northwest winds behind the baroclinic zone will clear out the sky during the morning, however moisture will be on the increase as a fast moving shortwave trough crosses during the evening hours. The column is fairly dry, so no measurable QPF is foreseen Saturday. Dry weather continues for the second half of the weekend despite less sunshine. Yet another passing short wave will bring clouds and given its stronger than the one Saturday isolated showers are possible north of the I-76 corridor in the late afternoon / early evening hours Sunday. Mid level heights continue to fall as we kick off a new work week. Most of the energy will reside along the lakes, so precip chances are small over northern WV and western MD when compared to northwest PA. Any shower will be brief. The bigger story is the spring like feel as daytime high temps do not leave the 60s Monday! This will be almost 15 degrees below normal. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Highlights: - Cool start - warm end temp wise - Unsettled weather returns Friday - No heat waves or high water threat Mid level heights increase with a ridge building into the eastern United States. This will bring temps back to normal levels by Thursday and above normal by a week from now. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... VFR weather will yield to MVFR and IFR cigs this evening in wake of the cold front. Drier air will work into the area toward 12Z bringing terminals back to VFR where they will stay for the balance of the forecast. Winds will be gusty from the WSW tomorrow afternoon with peak gusts around 20 kts. .OUTLOOK... Upper trough may bring occasional restrictions Sun and Mon in afternoon showers/storms. && .HYDROLOGY... The flash flood watch remains on track. The axis of highest QPF has shifted a little north to far southern PA where 24 hour amounts in excess of three inches are possible. HRRR shows a several hour period of moderate to heavy rainfall thankfully it is across a region that was not impacted by the nearly 4-6" of rain that fell in parts of Indiana county last evening. Warm rain process and PRE setup remain in place. PWATS are pushing two inches while warm cloud depths are in excess of 13kft. The low level jet continues to pump moisture from Cindy into our region. All of these point to enhanced convergence ahead of the front. River forecasts have been tweaked upward across Mon and headwaters of Ohio river. We still do not have any forecast points going to flood, but Pittsburgh, Elizabeth, and Charleroi are predicted to reach action stage. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...Flash Flood Watch until 2 AM EDT Saturday for MDZ001. OH...Flash Flood Watch until 2 AM EDT Saturday for OHZ039>041- 048>050-057>059-068-069. PA...Flash Flood Watch until 2 AM EDT Saturday for PAZ013-014- 020>023-029-031-073>076. WV...Flash Flood Watch until 2 AM EDT Saturday for WVZ001>004-012- 021-509>514.