textproduct: Burlington

WHAT HAS CHANGED

As of 237 PM EDT Friday...

No significant changes made with this forecast package.

KEY MESSAGES

As of 237 PM EDT Friday...

1. Patchy valley fog expected tonight with pleasant conditions on Saturday, followed by a chance of showers late Sunday afternoon.

2. Models trending drier for Tuesday but rain is expected to return Wednesday and Thursday.

DISCUSSION

As of 237 PM EDT Friday...

KEY MESSAGE 1: First forecast challenge is areal coverage/duration of fog after midnight tonight. Sfc analysis shows 1022mb high pres over the thumb of eastern MI, as a sfc cold frnt exits eastern New England. GOES-19 water vapor imagery shows large axis of dry air aloft moving acrs the Great Lakes into the NE CONUS this aftn, which should help quickly erode cloud cover by this evening, as sfc heating/instability is decreasing. Sounding data indicates modest caa and dry air advection continues thru 04z, before northwest flow weakens and shallow inversion strengthens. This sharpening inversion with clearing skies and light winds should allow for development of patchy dense fog with highest probability (80-90%) in favored mtn valleys. Temps wl range from the upper 30s SLK to lower/mid 50s near Lake Champlain.

On Saturday 1024mb high pres will build toward KBGM with deep dry layer shifting toward central New England by 18z, as a pocket of slightly better moisture in the 1000-500mb layer moves overhead. This combined with some weak instability wl help produce some shallow fair wx cumulus clouds, especially acrs the mtns. Progged 925mb temps btwn 14-16C support highs mainly in the 70s with comfortable humidity values. Saturday night is quiet with some patchy fog, but less than Friday night, as 925mb to 850mb southwest flow develops with some increasing moisture advection from west to east. Lows wl be warmer with values in the upper 40s to near 60F.

Sunday/Sunday night the forecast challenge wl be potential for showers and a few embedded thunderstorms as weak front approaches, along with s/w energy. Synoptic scale setup shows fast confluent 700- 500mb flow btwn closed cyclonic circulation over eastern Canada and Bermuda Ridge over the western Atlantic as weak channeled vortices moves acrs our cwa. Pw values range btwn 1.25 and 1.4", which is around 1 STD above normal ahead of approaching cold front near the International Border, while best instability is south of our cwa. Latest trends have shown less areal coverage of precip and mostly confined to the higher trrn on Sunday aftn, especially with 925 to 700mb southwest downslope flow here in the CPV. As winds shift to a favorable north/northwest upslope flow behind boundary a period of light upslope rain showers wl be possible on Sunday night, especially northern VT mtns into the eastern CPV. Highs Sunday will be in the 70s with slightly higher humidity with lows in the 50s to near 60F again on Sunday night.

KEY MESSAGE 2: The latest suite of global guidance is bringing high pressure across the Canadian Maritimes further south which is now expected to suppress much of the rainfall activity on Tuesday to our south. There is still the potential we could see models shift north slightly over the next few days as upper air analysis begins to sample several low amplitude features in the longwave trough. However, the idea that widespread rainfall across the region on Tuesday looks unlikely and the latest forecast has shows decreased rain chances as a result. The ECMWF and GFS both remain in good agreement with a series of frontal boundaries moving across the region Wednesday into Thursday with widespread rainfall likely. Deep layer ridging then looks poised to develop across the region with drier conditions expected Friday into next weekend.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

Through 00Z Sunday...With diurnal heating cut off, clouds will erode quickly this evening. The clear skies and light winds that result will allow the favored locations to develop fog between 06-09z. With CAA and dry air moving in behind today's front, fog will be more patchy with SLK, MPV, and EFK going IFR. RUT is a more borderline situation and for now have left it as TEMPO. Fog will burn off quickly in the morning as the shallow inversion gives way to mixing. Saturday will be pleasant all around with only some high clouds to deal with.

Outlook...

Saturday Night: VFR. NO SIG WX. Sunday: VFR. Chance SHRA, Slight chance TSRA. Sunday Night: Mainly VFR, with local IFR possible. Chance SHRA. Monday: Mainly VFR, with local MVFR possible. NO SIG WX. Monday Night: VFR. Slight chance SHRA. Tuesday: VFR. Chance SHRA, Slight chance TSRA. Tuesday Night: Mainly VFR, with areas MVFR possible. Likely SHRA, Slight chance TSRA. Wednesday: Mainly MVFR, with local VFR possible. Chance SHRA, Slight chance TSRA.

BTV WATCHES/WARNINGS/ADVISORIES

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