071 FXUS61 KALY 291633 AFDALY AREA FORECAST DISCUSSION National Weather Service Albany NY 1233 PM EDT Sat Jul 29 2023 .SYNOPSIS... An approaching cold front will continue to bring showers and thunderstorms today. Some storms may be severe along with localized flash flooding. The cold front will pass through late today, with much cooler and less humid conditions arriving for Sunday through early next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... * Flood Watch for flash flooding across for eastern New York south of the Adirondacks and Lake George area, including all of western New England through 8 pm today. * Heat Advisory in effect through 6 pm today for eastern Ulster, Dutchess and Litchfield Counties. .UPDATE...Quick update to issue a short duration Flood Watch for flash flooding for all areas south of the Adirondacks and Lake George area. Repeated clusters of showers and storms with torrential downpours could lead to some instances of flash flooding, especially in urban, low lying and poor drainage locations. Thus far most storms have been below severe levels, but one severe storm has been moving through southern Herkimer county. Expecting more severe storms to develop this afternoon as instability increases (MLCAPE 500-1000 J/Kg already), with damaging winds the main threat. .PREV DISCUSSION[0958]...Radar indicating a cluster of scattered showers with downpours developed across parts of Ulster, Dutchess and Litchfield County, possibly resulting from an outflow boundary due to prior upstream convection. Also, starting to see widespread showers with embedded T-storms with downpours moving east from the Tug Hill area. This activity will track into the western Adirondacks late this morning associated with a cold front and wave of low pressure gradually pushing southeast across upstate NY. Otherwise, not much instability yet in our area, but should occur by this afternoon due to significant breaks in the clouds this morning. An active afternoon still expected to occur with both severe storms and localized flooding. Before the showers and storms develop and track east and south, temperatures are expected to reach the upper 70s to mid 80s and cooler in higher elevations. CAPEs will increase to over 1000 j/kg ahead of the convection. South of the wind shift boundary, CAPEs could increase to around 2000 j/kg, mainly in the mid Hudson Valley to southern Berkshires and NW CT, where there is a slight risk for severe thunderstorms. Shear is not very high but there will be some enhanced low level forcing with a distinct low level wind shift and advancing low level thermal gradient on the leading edge of the cold advection. Damaging winds are the primary risk. Localized heavy rain and brief training of thunderstorms could produce urban, small stream flooding and standing water in low lying areas. Isolated flash flooding cannot be ruled out. A few showers and isolated thunderstorms approaching the mid Hudson Valley and NW CT. Outside of the isolated activity, increasing sun through the morning into early afternoon will help those areas to have the most heating. Temperatures will reach around 90 with heat indices around or above 95 and the Heat Advisory continues there. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... Lingering showers Saturday evening will exit and by Sunday morning, some clearing, cooling and drying. Sunday should be partly to mostly sunny and an isolated shower cannot be ruled out as upper trough axis overhead and cooling aloft. Highs Sunday in the 70s to near 80. Upper trough axis still in our region and another weak upper impulse tracks through the upper trough as continued cooling aloft occurs. Morning sun will become partly sunny in the afternoon with isolated showers and storms, mainly along and north of I-90. Still, there should be enough sun for temperatures to reach the mid 70s to near 80 and around 70 higher elevations. Clearing Sunday night with lows by Tuesday morning in the 50s with a few upper 40s southern Adirondacks and Lake George Region. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Long term period begins 12z Tuesday with upper trough axis overhead associated with an upper low in southeast Canada. With the cold pool aloft, diurnally-driven cumulus clouds and a few isolated showers could develop during the afternoon, so slight chance PoPs were added for most of the area. With NW winds advecting cooler and drier air into the region, highs will only be in the 60s for the terrain and mid to upper 70s for the valleys, which is a couple degrees below average. Any showers diminish quickly with the loss of daytime heating. Lows drop into the 40s (terrain) and 50s under partly to mostly clear skies Tuesday night as high pressure builds in from the west, allowing for favorable radiational cooling conditions. Wednesday through Thursday...Heights rise aloft and we get into some flat upper ridging with upper-level W/NW flow. The surface high remains overhead Wednesday, then begins to shift off to the east Thursday. The result will be dry conditions both days. Highs Wednesday will be a degree or two warmer than Tuesday with the coldest air aloft having moved off to our east. Highs Thursday will be in the 70s for the terrain and low to mid 80s for valley areas as we see warm advection with low-level southwest flow on the backside of the departing surface high. Lows Wednesday night will be in the 40s and 50s again. Thursday night through Saturday... Upper troughing approaches from the west, and a shortwave trough or closed upper low tracks to our north. The upper forcing will allow for the formation of a surface low that will track through southeastern Canada, and the trailing cold front will track through our region, bringing chances for showers and possibly some thunderstorms. As expected, there is some uncertainty in the timing of the front this far out, but overall the trend in the latest guidance has been for a slower frontal passage with the best chance for any showers/storms on Friday. This would allow for the front to clear our region to the east by Saturday, but due to the uncertain timing have maintained slight chance PoPs for Saturday, which could work out even with the front to our east as that would place the upper trough axis overhead. Thursday night and Friday night will be warmer, with lows in the 50s and 60s. Highs Friday and Saturday in the 70s and 80s. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... Through 06Z Sunday...Any fog/mist at PSF/GFL should lift by 12z, with VFR conditions expected this morning with increasing mid and high clouds. A few showers are possible near POU this morning, and have included VCSH to reflect this. Chances for showers increase towards the mid to late morning, at which point VCSH groups were introduced at the other TAF sites. The main batch of showers and storms moves in mid-afternoon which is an hour or so later than indicated with the previous TAF issuance. Once the steadier showers move in, conditions trend down to MVFR vsbys and MVFR to low-end VFR cigs. There is also a chance for thunderstorms at all of the TAF sites this afternoon, and prob30s were converted to tempo groups highlighting this potential with little change in the timing. In heavier showers and thunderstorms, MVFR to IFR vsbys and MVFR cigs are expected. Showers and storms come to an end around sunset this evening from northwest to southeast, with just some lingering SCT to BKN mid-level clouds and VFR conditions expected through the end of the TAF period, although borderline MVFR cigs are possible at PSF through most of tonight. Winds will be light and variable this morning, then pick up from the west at ALB and PSF to around 5-10 kt by mid to late morning. GFL will be north of a wind shift boundary, and winds here will be from the NE at 5-10 kt. POU, which remains south of the boundary through the morning, will see winds at 5-10 kt from the southwest. Winds increase to around 10 kt through the afternoon, then abruptly shift to the north at around 10 kt behind a cold frontal passage this evening. Winds remain northwesterly at 5-10 kt through 12z Sunday. Outlook... Sunday Night: No Operational Impact. NO SIG WX. Monday: Low Operational Impact. Isolated SHRA...TSRA. Monday Night: No Operational Impact. NO SIG WX. Tuesday: Low Operational Impact. Slight Chance of SHRA. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Chance of SHRA. && .HYDROLOGY... Flood Watch for flash flooding issued for all areas south of the Adirondacks and Lake George area through 8 pm today. Repeated clusters of showers and storms with torrential downpours could lead to some instances of flash flooding, especially in urban, low lying and poor drainage locations. Showers and thunderstorms with locally heavy rain will be possible today, especially for areas from around I-90 south. The Weather Prediction Center has included this area in a Slight Risk of excessive rainfall due to the potential for west- east oriented bands of locally heavy rainfall developing associated with thunderstorms. Rainfall of 1-2" in an hour may occur leading to localized flash flooding. A Marginal Risk remains for areas north of I-90. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...Flood Watch until 8 PM EDT this evening for CTZ001-013. Heat Advisory until 6 PM EDT this evening for CTZ001-013. NY...Flood Watch until 8 PM EDT this evening for NYZ038>041-047>054- 058>061-063>066-082>084. Heat Advisory until 6 PM EDT this evening for NYZ064>066. MA...Flood Watch until 8 PM EDT this evening for MAZ001-025. VT...Flood Watch until 8 PM EDT this evening for VTZ013>015. && $$ SYNOPSIS...NAS/JPV NEAR TERM...NAS/JPV SHORT TERM...NAS LONG TERM...Main AVIATION...Main HYDROLOGY...JPV