Area Forecast Discussion
Issued by NWS Pittsburgh, PA
Issued by NWS Pittsburgh, PA
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546 FXUS61 KPBZ 012319 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 719 PM EDT Mon Jul 1 2024 .SYNOPSIS... High pressure will provide dry and comfortable weather for the first half of the week before an unsettled pattern, with periods of showers and storms, takes hold to close out the week. Wednesday will be the hottest day of the week with lower 90s outside of the mountains. Pay close attention to the weather if you have outdoor fireworks plans on the 4th. && .NEAR TERM /THROUGH TUESDAY/... KEY MESSAGES: - Dry and comfortable thru tonight. - Temperatures below normal. ------------------------------------------------------------------- No changes to current forecast. High pressure will maintain comfortable - i.e dry and seasonably cool temperatures, for the remainder of today into tonight. Diurnal mixing is allowing for the dry air aloft to mix to the surface, bringing dewpoints into the mid- upper 40`s. Expect another night, not unlike last night with cool temperatures in the low 50`s as the surface high remains situated overhead. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... KEY MESSAGES: - Dry weather through Tuesday and most of Wednesday. - Temperatures warm both days with above normal readings returning on Wednesday. ------------------------------------------------------------------- The broad 500mb ridge centered over the southern states will build over the region and into New England Tuesday, with the surface high shifting to the east over time. Winds will veer more southerly as well, returning warm advection. Both the higher heights and waa will support a warming trend Tuesday into Wednesday. Temperatures are currently projected to be close to seasonal averages Tuesday but will once again rise above average on Wednesday. The aforementioned ridge will slowly break down on Wednesday, as a shortwave trough digs into the upper Midwest and pulls a surface cold front eastward. NBM begins to introduce probabilities for measurable precipitation Wednesday evening. The high probs (30-40%) are mainly over Ohio and NW PA at this time, expanding south and eastward overnight. Based on the current timing, models are keeping the bulk of the instability over Western and Central Ohio, though some instability (<500j/kg) is present in our eastern Ohio counties. Shear should be sufficient for storms as well, though the timing of the front and some lingering warm air aloft may cap things until late. At this time, SPC has a portion of the region in a marginal risk, and given the uncertainty, find this to be appropriate. The primary concern would be wind at this point, though a secondary concern is heavy downpours as PWAT values will be increasing through the rest of the week. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... KEY MESSAGES: - Showers and thunderstorms possible Wednesday night continuing through the end of the work week with the return of a more active pattern. - Showers and storms could pose a heavy rain/localized flooding threat Thursday ------------------------------------------------------------------- Cold front will continue to track southeastward but appears to stall/become more diffuse with time as it loses its connection with the associated low shifting into ne Canada. At the same time, the upper ridge will be flattening across the upper Ohio Valley, maintaining zonal flow through the end of the week. Shortwaves passing through this the zonal flow will support multiple rounds of showers and storms along the east- west oriented boundary in a moisture- rich environment. At this time, the placement of the boundary is generally south of I-70 but there is some uncertainty in it`s exact placement. That being said, the very moist airmass that will be present across at least a portion of the region (NBM has a 60-80% chance of PWATs nearing climatological max of 2 inches for the areas from I-70 south) could lead to training of thunderstorms and flooding rain potential. Still a bit too far out to dive into certain specifics, but will have to keep an eye on the pattern evolution and potential for an unsettled July 4th holiday. Machine learning continues to highlight some severe potential with this pattern as well as the front will initially be moving into a warm and moist airmass, though weak flow aloft resulting in limited bulk shear is helping to keep the overall threat low at this time. Still, this too will bare watching over coming days. Ensembles then signal an upper wave diving through the Great Lakes to close out the week, though uncertainty comes into play with how deep the trough is and subsequently how strong the surface low is and where it tracks. Consensus is to our north and dragging a cold front through sometime early in the weekend, but details remain fuzzy. && .AVIATION /23Z MONDAY THROUGH SATURDAY/... VFR is expected through the TAF period as high pressure tracks across the Upper Ohio Valley region. Expect wind to veer from NE-SE tonight and Tuesday, with speeds less than 10kt. .Outlook... VFR is expected through Wednesday. A slow moving front is expected to persist across the region Wednesday night through Friday, bringing showers, thunderstorms and associated restrictions back to the area through the end of the week. A cold front will maintain showers, thunderstorms and ocnl restrictions on Saturday. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...34 NEAR TERM...34 SHORT TERM...34 LONG TERM...Cermak/34 AVIATION...WM