Area Forecast Discussion

WHAT HAS CHANGED

As of 222 PM EDT Saturday...

No significant changes made with this forecast package.

KEY MESSAGES

As of 222 PM EDT Saturday...

1. Light rain and cool temperatures expected on Sunday, followed by drier and seasonable cool weather for the start of the new work week.

2. Quiet weather for the extended

DISCUSSION

As of 222 PM EDT Saturday...

KEY MESSAGE 1: Sfc analysis indicates weakening 1024mb high pres stretching from Eastern Canada into central Maine, while weak 1010mb low pres is over central Iowa with warm front extending into the Ohio Valley. This area of low pres wl race toward the Ohio Valley tonight with increasing clouds acrs our fa and light rain developing along the warm frontal boundary by mid-morning Sunday. Temps drop quickly this evening, due to very dry bl conditions/light winds but warm after midnight. Lows generally mid 30s NEK to mid/upper 40s Champlain/St Lawrence Valleys. The highest pops and greatest qpf wl occur btwn 13z and 20z on Sunday, per best moisture and lift proggs. Given the lack of instability and highest pw values >1.30" staying south of our cwa, along with relatively quick movement of system, thinking qpf wl range in the 0.20" to 0.50" for most areas. Did note some southeast downslope component in the bl to 900mb wind fields, which could cause some localized shadowing along the western slopes. In addition, RAP/HRRR sounding data at CLC indicates good mixing below inversion near 1000 feet of 25 to 29 knots, so thinking a brief lake wind advisory wl be needed btwn 10z- 15z Sunday morning. As rain arrives, conditions wl stabilize and mixing/winds wl decrease, especially by early aftn. Next noticeable impact wl be the relatively cool high temps for Sunday, given clouds/precip. Expecting highs only mid/upper 40s mtns to mid/upper 50s warmer valleys. A cool/raw day is anticipated with intervals of light rain.

Sunday night, sounding data indicates strong subsidence inversion developing under caa and blocked flow. Given this synoptic scale scenario with rainfall in the past 6 to 12 hours, expect areas of low clouds/drizzle, especially favorable upslope mtn elevations above 1000 feet with some fog possible. Temps wl range from the mid 30s to mid/upper 40s with no frost formation expected given the caa advection and bl mixing.

Monday-Tuesday...a period of very quiet wx is anticipated as strong 1030mb high pres builds toward the International Border from Hudson Bay. This wl produce a cool-dry anticyclonic flow of air acrs our cwa, with pw values dropping <0.50". This deep dry layer wl result in large diurnal spread in daily temps and sharp elevation depend gradients from mild valleys to cool summits. Have utilized the mtn max temp tool to highlight this thinking, which supports highs l/m 40s summits to upper 50s to mid 60s valleys for both Monday and Tuesday. Conditions look favorable for frost/freeze headlines on Monday night/Tuesday morning for parts of the SLV and n-central VT valleys. Lows generally mid/upper 20s SLK/NEK to mid/upper 30s, except mid 40s near Lake Champlain.

KEY MESSAGE 2: A high pressure to our north and a low pressure to our south will bring us several days of dry weather and cool temperatures, perfect for your outdoor plans. Daily highs will be in the 60s through Thursday before the forecast becomes less clear. WHile the GFS has backed off from the more extreme scenario it was painting during the last forecast cycle, the low pressure to our south will move up the coast sometime late in the week or into the weekend, bringing some rain to the regions.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

Through 00Z Monday...VFR expected through 12Z under light winds as mid to high cloudiness increases over time after 06Z. Periods of light rain will then move into the region in the 12-15Z time frame and generally persist through late afternoon before tapering off late. Conditions gradually lower to MVFR at most sites with exception being KMSS which should remain largely VFR. Have opted to stay away from some of the more pessimistic guidance showing more widespread IFR cigs tomorrow afternoon given southeasterly flow regime and have only offered this scenario at KSLK at this point as confidence remains low on this playing out as advertised.

Outlook...

Sunday Night: Mainly VFR, with local IFR possible. NO SIG WX. Monday: Mainly VFR, with local IFR possible. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. NO SIG WX. Wednesday: VFR. NO SIG WX. Wednesday Night: VFR. NO SIG WX. Thursday: VFR. Slight chance SHRA.

MARINE

As of 222 PM EDT Saturday...

A brief Lake Wind Advisory maybe needed between 6 AM and 10 AM on Sunday morning for breezy south to southeast winds of 15 to 25 knots, especially on the open waters. The winds will quickly decrease to 10 to 15 knots once the rain arrives and helps to stabilize the winds from mixing down over the warmer waters. Waves generally 1 to 3 feet, but localized near 4 feet possible on Sunday morning.

BTV WATCHES / WARNINGS / ADVISORIES

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