textproduct: Burlington

WHAT HAS CHANGED

As of 301 AM EDT Saturday...

Increased chances for scattered showers this afternoon. Frost potential for tonight remains uncertain.

KEY MESSAGES

As of 301 AM EDT Saturday...

1. Showery weather prevails today with temperatures remaining below normal.

2. Frost is possible tonight and perhaps again Sunday night, though additional showers Sunday night into Monday may preclude frost formation.

3. Confidence continues to increase for an unsettled pattern with below normal temperatures for mid to late next week.

DISCUSSION

As of 301 AM EDT Saturday...

KEY MESSAGE 1: An area of light precipitation associated with a weak upper shortwave will continue to move across the region early this morning. Rainfall amounts have been fairly lackluster so far, with most areas seeing around a tenth of an inch or less over the past 6 hours. Temperatures in the higher elevations of northern NY and in central and northeastern VT are in the mid to upper 30s, while mountain summits are generally in the mid 20s to around 30. Therefore, expect the higher elevations, mainly above 1500 ft, will see precipitation in the form of wet snow. A few inches of accumulation is possible atop the highest summits. Some snow may mix in above 1000 ft from time to time, but little to no accumulation is expected.

This main batch of precipitation will exit to our north and east by mid/late morning. However, additional scattered showers are expected to develop this afternoon as low level lapse rates steepen in response to cold air advection and some daytime heating. SB CAPE values could approach 150 J/kg or more, so some of the showers may be relatively robust, capable of a quick downpour. Rainfall amounts through today will mainly be a quarter of an inch or less, but a few spots may see more if a heavier shower moves overhead. Otherwise, it'll be a cool day with highs only in the mid 40s to mid 50s under partly to mostly cloudy skies.

KEY MESSAGE 2: Showers will come to a quick end this evening as daytime heating wanes. Ridging will briefly build in Sunday night into Monday, with light winds and dry conditions. However, the amount of cloud cover is still uncertain as model guidance shows some lingering 700-900 mb moisture, potentially enough to limit frost potential under partly to mostly cloudy skies. Have kept frost in the forecast for now, but do not have enough confidence at this time to issue any headlines. However, anyone with sensitive outdoor vegetation may want to take precautions, just in case.

Dry weather persists on Sunday, then another round of showers moves in Sunday night into Monday. This, too, should limit any frost, though it will depend on how quickly showers and associated cloud cover spreads over the region. Highs on Sunday will be a few degrees warmer than today, while Monday will be even warmer still after a warm frontal passage. Highs will be in the mid 50s to mid 60s.

KEY MESSAGE 3: The latest WPC forecast shows 7 periods Tues thru Fri of at least 55 or greater pops for our most of our cwa, especially the higher trrn of northern NY and VT. Tuesday wl be the warmest day as southwest flow and llvl waa helps to advect progged 925mb temps 14C and 16C ahead of approaching cold frnt. This supports highs well into the 70s as most of the precip should hold off until sunset. GFS does show an axis of weak instability thru 00z, but most of the precip is post frontal, so not anticipating much potential for strong or severe storms. Have kept isolated mention for thunder.

Mid/upper lvl trof deepens acrs the central Great Lakes on Weds into Thurs, as thermal gradient sharpens along the eastern CONUS. The forecast spread increases for mid to late week with regards to phasing of northern and southern stream energy, along with development and track of sfc low pres. Crntly 00z GFS and ECMWF are the most aggressive with development of closed 7-5h circulation and deepening sfc low pres and producing a widespread moderate to heavy rain event for Weds into Thurs. Meanwhile, CMC is much less amplified and more progressive with tracking sfc low pres off the eastern seaboard, which results in less rain. For now have continued with WPC pops of 70-85% for this time frame, given the relatively good agreement in at least some precip occurring, just uncertainty on placement and how much attm. Temps wl trend below normal, especially daytime highs by Weds and Thurs, as cooling occurs with development of mid/upper lvl trof and areas of precip. Highs generally in the mid/upper 30s summits to upper 40s to mid 50s, while lows are in the 30s and 40s. Deep cyclonic flow lingers into next weekend, with additional s/w energy and pockets of moisture, combined with upslope flow supports the threat for additional showers and below normal temps.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Through 12Z Sunday...A challenge taf package this morning with regards to cigs heights across our 7 taf sites. Currently a mix of mvfr/vfr conditions with some light rain and snow showers impacting our tafs. Thinking MVFR cigs and vfr vis at our mtn taf sites through 15z, before all site trend toward VFR. Additional light rain showers are likely this afternoon, with 30-40% probability at SLK/EFK and MPV, less chance in the valleys. Any showers could briefly produce MVFR vis/cigs, before activity decreases by sunset. Utilized PROB30 groups to cover this potential. Some sounding data hints at potential MVFR cigs redeveloping toward 03z, with even some lower cigs possible. For now trended a few sites toward IFR. Winds are generally light from the north/northwest.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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