Area Forecast Discussion
Issued by NWS Buffalo, NY

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136 FXUS61 KBUF 150513 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 113 AM EDT Sat Jun 15 2024 .SYNOPSIS... High pressure moving in from the upper Great Lakes will supply us with fantastic weather for the weekend. Oppressive heat and humidity will then DOMINATE our weather next week with dangerously high apparent temperatures, peaking in the upper 90s to low 100s Tuesday and Wednesday. && .NEAR TERM /THROUGH TONIGHT/... Tonight, expansive high pressure centered over the upper Great Lakes will slowly drift to the southeast towards our region. Other than some patchy areas of clouds, this scenario will promote moonlit skies tonight with temperatures dipping to below normal levels. Mins will range from the low to mid 50s in most areas, to the mid and upper 40s across much of the Southern Tier and also across Lewis County. The large area of high pressure will move directly over our region Saturday and Saturday night. This will support mainly clear skies, although it will be on the cool side of normal with Saturday afternoon temperatures only in the 60s to near 70. Mins Saturday night will be lower than those of tonight for much of the area. Enjoy this pleasant weather that will be in place through this weekend, before dangerously oppressive heat and humidity takes hold for much of next week. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... Broad mid-level ridging centered across the Great Lakes Sunday will continue its eastward progression into the eastern Great Lakes through Monday. Meanwhile within the ridging, a shortwave trough will ride the top of the ridge Sunday and Monday well to the north of the region. While this shortwave trough indicates some active weather Sunday night through Monday, its placement well to the north should keep any activity outside of the area. This being said, have slight chances for showers and thunderstorms Monday afternoon. Outside of this, deep southerly flow will advect in warmth and moisture from the Gulf of Mexico initiating the heat wave for the middle portion of the week. Highs Sunday will topple off in the low to mid 70s across the North Country and upper 70s to low 80s elsewhere. Monday will be warmer with highs in the mid to upper 80s across most of the region, however across the climatologically warmer places in the Genesee Valley a few low to mid 90 readings will be possible. These 90 degree readings along with the humidity will create heat index values to range in the mid to upper 90s. && .LONG TERM /TUESDAY THROUGH FRIDAY/... ...Dangerous Heat Wave To Impact The Region Next Week... A very strong 500mb ridge will anchor itself across much of the eastern CONUS and western Atlantic through much of the week, which will dominate the sensible weather across the eastern Great Lakes. NAEFS ensemble guidance continues to indicate this ridge will be of anomalous strength with 500mb heights and 850mb temperatures in the 99th percentile, if not exceeding the maximum climatological values for the Northeast through Thursday. Deep anticyclonic flow around the resultant Bermuda High will cause hot, humid air to surge across the eastern CONUS. Given the strong signal from nearly all available long range guidance packages, confidence is high in a prolonged stretch of oppressive summer heat and humidity lasting through much of the week. Not much change to previous forecast packages with daytime highs solidly in 90s Tuesday through Thursday. Highest temps will be in the interior valleys, while cooler temps will be found immediately along the lakeshores and immediately northeast of both lakes (including Downtown Buffalo) as a persistent southwest flow advects cooler marine air off the lakes. Tuesday and Wednesday still seem like the peak days of excessive heat and humidity with low 100s possible in interior valleys. This heat comes as dewpoints climb into the low 70s, which will cause overall heat indicies in the afternoon to climb into the mid 90s to lower 100s. An upper level trough over south-central Canada will move east through the end of the week. The approaching trough will begin to suppress the strong ridge over the eastern Great Lakes region Wednesday night. Based on the NAEFS, 850mb temperatures will begin to fall into the upper teens Thursday through Friday, HOWEVER this may only result in a few degrees difference from Tuesday and Wednesday, continuing the heat wave across the forecast area. For context, daytime highs average the upper 70s for Buffalo, Rochester, and Watertown during the days of June 18-21. Little relief is expected overnight with overnight lows in the upper 60s to mid 70s. Otherwise...The primary forecast uncertainty through much of next week continues to be the potential for convection. Daytime surface based instability will be present each afternoon with dewpoints climbing into the upper 60s and low 70s although the strong ridge should preclude much of the diurnal convective potential with strong capping expected to be in place. Given the low confidence in shower and storm timing and coverage, PoPs values remain on the low side (15-30%) through Thursday. && .AVIATION /05Z SATURDAY THROUGH WEDNESDAY/... Widespread VFR flight conditions will remain in place overnight, with just some patchy areas of low level VFR clouds. High pressure will build overhead on Saturday, providing dry weather with VFR flight conditions and light winds through the end of the TAF period. Outlook... Saturday night through Monday...VFR. Tuesday through Wednesday...VFR, but a slight chance for afternoon thunderstorms inland from the lakes. && .MARINE... Northwesterly winds behind a cold front late this evening will generally remain below 15 knots while veering more northerly overnight. Conditions will remain below headline criteria through the weekend, although there may be a few periods with some light to moderate chop, especially on eastern Lake Ontario later tonight into Saturday morning, then western Lake Ontario Sunday afternoon. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...None. && $$ SYNOPSIS...JM/RSH NEAR TERM...JM/RSH SHORT TERM...EAJ LONG TERM...HSK/PP AVIATION...JM MARINE...JM