LOCAL WEATHER CONDITIONS AT Franklin, Venango Regional Airport Temperature 35.6 F / 2 C Dew Point 30.2 F / -1 C Humidity 81% Wind Speed 0 Wind Direction N 0 Degrees Visibility 10 Miles Sky Conditions Clear Current Weather Barometer 30.32 Inches Issued At 04/28/2025 04:56 $$ |
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Area Forecast Discussion
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FXUS61 KPBZ 280844 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 444 AM EDT Mon Apr 28 2025 .SYNOPSIS... High pressure overhead will make for a dry day today. A cold front will bring a threat of severe weather on Tuesday. The pattern is expected to remain busy into Thursday as well with another chance of severe weather. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Temperatures will be above normal this afternoon - Low relative humidity expected this afternoon. ------------------------------------------------------------------- Conditions this morning will feature calm winds and clear skies allowing some areas of frost to form this morning. Temperatures this morning are well below normal on the order of 10 degrees in some instances. Also noted the extreme dry air in place this morning with some instances of 10 degree dew point depressions. This will make sure that any instances of fog are in river valleys or very isolated. Heading into the day, high pressure will scoot to the east a bit but remain largely over the region. This will keep dry conditions in place with sunny skies and light winds. With a higher sun angle and the dry air, did use the 90th percentile for temperatures and the 10th percentile to cover the dew points. South-southwest winds will be in place through the day with gusts only reaching 15 mph in some cases. Tonight will feature another wild swing in diurnal trends. Low temperatures tonight will be around 10 degrees above normal given the modest warm air advection through the day. Cloud cover will increase in the mid and upper levels in advance of the cold front. Southwest winds will begin to increase towards dawn as well Tuesday morning with gusts up to 20 knots already. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY/... KEY MESSAGES: - Temperatures peak Tuesday before the arrival of a cold front. - Severe weather is expected Tuesday late afternoon and into the evening with all hazards possible. - A trailing boundary is possible on Wednesday with additional convection possible. ------------------------------------------------------------------- Tuesday will feature the arrival of the shortwave trough into the region with the axis setting up over the central Great Lakes and pushed east southeast through the evening and overnight. The only thing that stands as a possibility is the development of showers ahead of the line eating up instability. However, the amount of dry air leading up to this might limit convection to the event itself. Ensembles hint at the potential for precip as early as 12Z to 15Z with the line of thunder beginning to track southeast after 18Z. That said, the NBM has a bit more confidence in the potential suggesting a 70% to 90% probability of over 1000 J/Kg SB CAPE, and 50% prob for 1500 J/Kg or over. This increase happens in the 18Z to 21Z time frame. During this time as well, the models suggest around 40kts to 50kts of 0-6Km bulk shear. This in conjunction with the some models suggesting a 21Z to 00Z arrival of the line. Given the difference in arrival in certain solutions, will go with an 18Z to 00Z timeframe with most likely being 20Z to 23Z. Given the trends the damaging winds and large hail will be the main threat. There is also a tornado threat but a 2% prob was given. This is due to while there is plenty of shear and instability, the amount of dry air in place heading into this event will likely make this more unlikely. This raises question as the NBM is also not giving much in the way of QPF. Finally, the trends do indicate a line of convection developing but remaining more intact to the northern areas. Thus will likely see a solid MCS line over the north with some broken line convection to the south-southwest. The final aspect to watch is the 700MB flow is more perpendicular to the boundary over the northern area and more likely to push through the area. The southern portion of the forecast area suggests the steering flow being more parallel to the boundary and may not be as potent and thus, the area of Pittsburgh and south might see lingering weaker cells. The main severe threat will come to an end by 05Z. That said, this will answer the question for Wednesday on whether a boundary will be draped across the southern portion of the forecast area. Wednesday's outlook will be greatly influenced by how far southeast the surface cold front progresses as weak shortwave ridging develops overhead. If the front is able to drop south of the area before stalling, then most of the region will be dry with more seasonable temperature. If the front struggles in that progression and stalls in the region, a few light rain showers and pockets of drizzle may be possible south of the boundary along with increased cloud cover. It is likely that the boundary does not push south all the way through the area. A possibility of reinvigorated convection can't be ruled out for Wednesday with any breaks in cloud cover. Temperatures are expected to be in the mid 70s over the southern portion of the forecast area. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... KEY MESSAGES: - There is a potential for another round of severe weather on Thursday. - Multiple rounds of heavier rain possible to end week before a significant weekend cool down on Sunday. ------------------------------------------------------------------- Confidence is increasing for a wet end-of-week period due shortwave movement within moist, southwest flow ahead of a developing deep Mississippi River Valley trough. Ensemble means show potential for another severe weather day Thursday dependent on degree of heating/clearing. That said, the NBM has been advertising some healthy SB CAPE values for Thursday afternoon over the past few runs. The latest suggests a 50% to 70% prob of 1000 J/Kg of SB CAPE. Impressive given the Day 4 setup. This will be one to watch for severe and also hydro as the WPC has put a Marginal Excessive Rainfall Outlook. Once this Thursday shortwave passes through, a blocking ridge just off the east coast will keep an extended boundary along the west side of the Appalachians with a second shortwave trough tracking along the boundary. This will continue to keep rain fall chances over the area for Friday and Saturday. The extended will end with the front finally passing through late day Saturday. This will lead to the potential of another cool down potentially requiring Frost Freeze products on Sunday morning. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... VFR conditions continue through Monday as upper ridging and SFC high pressure hold on. A few patches of mid and high level clouds will move through overnight. Light and variable winds become SEerly by late morning with speeds largely less than 10KTs. Outlook... Shower and thunderstorm chances will increase Tuesday and Tuesday night with the approach and passage of a cold front. Mainly VFR is expected early Wednesday before restriction and shower potential returns later Wednesday and Thursday as the front returns north as a warm front. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...Shallenberger NEAR TERM...Shallenberger SHORT TERM...Shallenberger LONG TERM...Shallenberger AVIATION...AK |