Area Forecast Discussion
Issued by NWS Albany, NY
Issued by NWS Albany, NY
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756 FXUS61 KALY 070030 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 830 PM EDT Sat Jul 6 2024 .SYNOPSIS... Widely scattered showers and thunderstorms will end this evening, followed by dry conditions tonight into Sunday. Humidity levels will be slightly lower on Sunday, but very warm temperatures will persist. Above normal temperatures will continue through early next week, with humid conditions returning. The next chance of showers and thunderstorms arrives Tuesday, as a frontal system approaches form the west. && .NEAR TERM /THROUGH SUNDAY NIGHT/... .UPDATE...As of 830 PM EDT, heat advisory has been allowed to expire, as heat indices have generally dropped into the mid 80s to lower 90s and will keep falling this evening. Weak cold front was now settling south and east of Albany, extending into the northeast Catskills and into SW VT. Latest SPC Mesoanalysis indicates decreasing ML CAPES, generally under 500 J/kg for areas west of the Hudson River, and 500-1500 J/kg to the east, highest across NW CT. Will have to watch for any additional convection as the front continues sagging southeast into the Taconics, Berkshires, and especially Litchfield County where greatest reservoir of instability remains, despite some earlier convection. However, with sunset occurring, overall instability should decrease over the next 1-2 hours. Based on mesoanalysis, will keep PoPs for areas remaining southeast of the front, but only in the slight chance to low chance range due to expected limited coverage. Will also keep mention of gusty winds with thunderstorms for another couple of hours. Elsewhere, chances of additional showers/thunderstorms has ended. Otherwise, gradual decrease in humidity levels is expected from NW to SE this evening, most noticeable for areas along and north of I-90, and west of I-87. PREVIOUS [315 PM EDT]...A weak cool front will continue to slowly move eastward across the area into this evening, with an upper level short wave tracking east across the lower Great Lakes. This will continue to result in just enough forcing for widely scattered showers/T-storms into early evening. Environment continues to support an threat of isolated severe storms producing damaging wind gusts. SPC Mesoanalysis indicating 1000-1500 J/Kg MLCAPE and 50-60 kt of effective shear. The Storm Prediction has a Marginal Risk (level 1 of 5) of severe storms. Poor mid level lapse rates and moist environment with high freezing levels mitigate hail threat, but locally heavy rainfall will occur with isolated flash flooding possible where any persistent or repeated downpours occur. The heat risk lowers after sunset, with humidity levels dropping slightly in wake of the front. Low temperatures should range from the upper 50s in the Adirondacks to upper 60s in the mid Hudson Valley. Patchy fog will may occur, especially for locations that receive rainfall today. Sunday looks to be a quiet day with a broad SW flow aloft and surface high pressure building in from the west. Subsidence should halt any convective development, with just some fair weather cumulus clouds around. A warm air mass will be in place with 850 mb temperature anomalies around +1 STDEV, so with sufficient sunshine highs should reach the mid to upper 80s in lower elevations, with cooler upper 70s to lower 80s in the higher terrain. Humidity levels will be lower than recent days, with dewpoints mainly in the lower to mid 60s. Surface high pressure will be positioned over the region Sun night, with flat ridging aloft. It should be mostly clear with lows ranging from mid 50s in the Adirondacks to mid 60s in the Hudson Valley. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Monday should be another rain-free day with surface high pressure in place and flat ridging aloft. Tempertures will be slightly warmer as 850 mb temperature anomalies rise to a solid +1 to +2 STDEV. Humidity levels will also be creeping up into the upper 60s to near 70, so max heat indices may reach or slightly exceed 95F in the mid Hudson Valley. A Heat Advisory may eventually be needed. Actual highs look to be in the lower 90s in the lower elevations. Dry, but warm/humid conditions expected Mon night with lows in the 60s to around 70. The next chance of showers/T-storms arrives Tue as a frontal system and upper level trough approach from the Great Lakes. There are timing differences in the guidance, so it is unclear when convection will initiate yet. Some guidance has the upper trough lagging farther back to the west which delays showers and storms until later in the day into evening, which is more in line with NBM favoring likely PoPs during this time. Depending on timing and eventual instability/shear parameters, there could be some stronger storms. Also locally heavy rainfall may occur due to anomalously high PWATs (increasing to +1 to +2 STDEV). Prior to convection developing, the combination of temperatures in the lower 90s and dewpoints in the lower 70s could yield max heat indices the mid/upper 90s in valley locations. Scattered to numerous showers and T-storms expected to persist into Tue night depending on the timing of the upper level trough moving in. It will remain warm and humid with lows in the 60s to around 70. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Latest guidance indicating the aforementioned front may stall somewhere across the southern part of the area on Wed, so will need to maintain a chance of showers and T-storms. Temperatures will be somewhat cooler, especially north of the front, but still slightly above normal with mid to upper 80s in lower elevations. Forecast confidence then decreases considerably in the Thu to Sat timeframe. The main question is where the remnant circulation of post-tropical cyclone Beryl ends up going, as it potentially interacts with the front in the Northeast. Some guidance has it tracking NE across the Tenn/Ohio Valley regions into Thu, then into the lower Great Lakes Thu night into Fri. Depending on the track, this could bring widespread and potentially heavy rainfall given its tropical origin. Will continue to monitor trends and mention mainly chance PoPs for now until forecast confidence increases. Slightly above normal temperatures and relatively humid conditions should persist through the long term period, with above normal temperatures continuing to be favored further out in the 8-14 day outlook from the Climate Prediction Center. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... Mainly VFR flying conditions expected this afternoon but given how humid it is, isolated showers and thunderstorms have develop this afternoon mainly away from the terminals. However, with aggregated cumulus in place and a weak boundary approaching, the atmosphere is primed for scattered showers and storms to form this afternoon. Included TEMPO groups at all the terminals for brief IFR visibilities and MVFR ceilings to occur during any thunderstorm. For ALB, POU, and GFL, we have the TEMPO group from 18 UTC to 00 UTC during any storm with PSF delayed a bit until 20 UTC to 01 UTC. A few storms may linger until 01 - 03 UTC but given low confidence, we ended the TEMPO group at 00 to 01 UTC for all the sites. Showers and storms end before Midnight with clearing skies thereafter. Any terminal that experiences rain this afternoon will likely see fog develop as the low-levels remain moist. We show MVFR visibilities at ALB and POU from 06 - 12 UTC with IFR visibilities at GFL and PSF. Any fog lifts by 12-13 UTC at the latest with VFR conditions the remainder of the TAF period. Southerly winds ranging 5-9kts this afternoon become light and variable after 00 UTC. Then, winds shift out of the west to northwest by 15-16 UTC becoming sustained 5-8kts. Outlook... Sunday Night: No Operational Impact. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: Moderate Operational Impact. Chance of SHRA...TSRA. Tuesday Night: Moderate Operational Impact. Likely SHRA...TSRA. Wednesday: Moderate Operational Impact. Chance of SHRA...TSRA. Wednesday Night: Moderate Operational Impact. Chance of SHRA...TSRA. Thursday: Moderate Operational Impact. Chance of SHRA...TSRA. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...JPV NEAR TERM...KL/JPV SHORT TERM...JPV LONG TERM...JPV AVIATION...KL/Speciale