Area Forecast Discussion

WHAT HAS CHANGED

As of 238 PM EDT Saturday...

No significant changes made with this forecast package.

KEY MESSAGES

As of 238 PM EDT Saturday...

1. Scattered showers and thunderstorms are expected into the evening hours with a few stronger storms possible, additional showers likely on Sunday.

2. Warm and humid weather is expected towards the latter half of next week, with potential heat risk concerns.

DISCUSSION

As of 238 PM EDT Saturday...

KEY MESSAGE 1: GOES-19 mid lvl water vapor imagery potent s/w energy over the central Great Lakes with sfc low pres approaching the Ottawa Valley, while a warm frnt is draped acrs central/northern VT. Our potential for strong/severe storms this aftn continues to be a conditional threat based on amount of clearing/instability that can develop. Latest trends on the GEO-Color imagery indicates overcast skies acrs most of VT with some breaks developing in the warm sector/dry slot over central NY, angling toward southern Dacks/southern VT. RAP sfc based CAPE analysis shows 1000-1500 J/kg within this sector, which wl angle toward c-southern VT by 21z. This instability combined with potent s/w energy diving toward the SLV, should provide enough dynamical support to enhance scattered convective acrs our cwa btwn 21z-02z this evening. The 0-6km wind shear is 35 to 40 knots, enhanced by a ribbon of stronger 700mb winds of 40 to 45 knots, per latest upstream VADS at BUF/TYX and BGM. If enough instability can develop to sustain updrafts and prevent outflow air from cutting off convection, a few mini bowing line segments are possible, with greatest potential over Rutland/Windsor counties, where progged instability wl be the highest. Continued enhanced wording with small hail and gusty winds over southern counties. Given the fast westerly flow aloft, storm motions should be 20 to 30 knots and drier developing aloft, feel the potential for heavy rainfall/flash flooding is very low thru this evening. QPF wl vary greatly based on areal coverage of convection but basin wide averages wl be in the 0.25 to 0.75" thru tonight. Also, did note some stronger sfc wind gusts outside convection over western NY associated with better mixing within the warm sector, so have placed this into our region thru this evening.

As sfc low pres shift into central Maine by 12z Sunday deep northerly flow develops with additional s/w energy dropping south acrs our cwa. This s/w energy with additional mid lvl moisture wl produce more showers on Sunday acrs our cwa. However, instability is minimal given timing of forcing, so probability of thunder is low (<15). Have kept pops 70 to 90% thru 18z Sunday, before quickly tapering off by 00z Monday. Highs mainly in the 70s on Sunday.

Mid/upper lvl ridge builds into the northeast CONUS Sunday into thru Tuesday. This wl support a warming trend with dry conditions prevailing. Still noted some bl winds in sounding data on Monday morning, so did not place fog into the grids, but something to watch if winds can decouple, especially northern Dack valleys. Progged 925mb temps btwn 16-18C Monday support highs mid 70s to lower 80s. These 925mb temps warm 18-20C by Tuesday, supporting highs mostly in the 80s with comfortable humidity values thru early next week and cool overnight lows.

KEY MESSAGE 2: As we head through next week, increasingly warm and muggy conditions are expected as the region remains under southwesterly flow. High temperatures by the middle of next week are expected to be in the upper 80s and lower 90s, with increasing dewpoints in the 60s making it feel quite muggy. Overnight lows will provide little relief with temperatures only dropping into the 60s. These conditions look to be the hottest of the year so far, with potential for heat related illness as HeatRisk region reaches Moderate and Major levels and headlines may be required as we get closer. In addition to the heat, there will be shower and thunderstorm chances Thursday and Friday as weak trough moves into the region with the humid airmass supporting development.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Through 18Z Sunday...A period of variable flight conditions is expected across the region this afternoon as showers and potential thunderstorms develop across the region after the initial round of showers this morning. Given the overall uncertainty in timing and development of thunderstorms and showers, PROB30 groups were utilized to highlight the most likely period of convection at each terminals, with thunder chances beginning to drop off towards 00Z or so as the main boundary moves through. Ceilings are expected to lower overnight, with terminals trending towards MVFR with ceilings generally between 1500 and 2500 ft AGL, with IFR ceilings possible especially KSLK. Additional showers are expected to develop overnight into the morning hours tomorrow. Winds continue to be southerly this afternoon, becoming more westerly behind the convection this evening. Some gusts of 15 to 25 knots will be possible In addition to the surface winds, pockets of LLWS are possible overnight.

Outlook...

Sunday Night: VFR. Patchy BR. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. NO SIG WX. Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA. Wednesday Night: Mainly VFR, with local IFR possible. Chance SHRA, Slight chance TSRA. Thursday: MVFR/IFR conditions possible. Chance SHRA, Chance TSRA.

BTV WATCHES / WARNINGS / ADVISORIES

VT...None. NY...None.