textproduct: Burlington

WHAT HAS CHANGED

As of 252 PM EDT Wednesday...

No significant forecast changes.

KEY MESSAGES

As of 252 PM EDT Wednesday...

1. Increasingly mild, breezy, and showery weather is expected through Friday in advance of a cold front. Sharply drier and sunny weather will return on Saturday.

2. Turning cooler early next week with low chances of showers Sunday night into Monday.

DISCUSSION

As of 252 PM EDT Wednesday...

KEY MESSAGE 1: It has been hard to scour out our low cloud deck in Vermont, and especially the eastern Champlain Valley, today. Partial sunshine has gradually broken out this afternoon with temperatures responding in kind, reaching the 70s as of this writing in southern St. Lawrence County. The warming trend will be more noticeable with our nighttime temperatures as southerly flow and increasing moisture helps keep us warmer than normal as we move into October. Looking upstream, there are light showers streaming eastward across the eastern Great Lakes, so a few sprinkles are possible tonight along with plentiful cloud cover. Further modification of our air mass will set the stage for unusually warm low temperatures for Friday; the EFI highlights the southern and eastern portions of Vermont especially, where low temperatures in the low 60s would be near/above daily records. (Note sharply cooling temperatures Friday night prior to midnight will make records unlikely.)

The latest guidance has backed off on chances of rain for tomorrow afternoon, but have maintained some PoPs out of continuity. By and large, any appreciable rain will hold off until after sunset. From the evening into the early morning hours Friday, showers will only slowly sag southeastward such that a good soaking rain looks mainly across northern New York from St. Lawrence to Clinton Counties, and possibly extending through northwestern Vermont. Friday morning much of the steady, and widespread rain, is favored to expand southeastward through the remainder of northern Vermont and the Adirondacks as the system's primary cold front passes through. The shorter duration of rain, and plume of anomalous PWAT (REFS mean at about 1.8" is near the 99th percentile) dwindling as it pushes southeastward, leads to decreasing rainfall amounts during the day. Moderate rainfall totals near 1" are most likely in pockets of northern New York near US Route 11/western foothills of the Adirondacks, and northwestern Vermont due to combination of the orientation of the steady rain Friday morning and upslope west- southwesterly flow. While southerly/southwesterly winds will be noticeable, especially before rain arrives, the peak of the low level jet (about 35-40 knots in the 850-925 millibar layer) will be concurrent with the rain and during the early morning hours. As such, any impacts look modest and mostly centered around recreation and aviation interests with strong stability present.

A secondary cold front is evident in higher resolution model guidance for Friday afternoon, and it may have sufficient convergence to organize scattered to numerous showers. Given the piecemeal nature of this front, unsurprisingly there is limited deep moisture by this time so despite ample low level moisture and shear, instability will be very shallow and no thunderstorm risk is evident. Brief downpours will be possible with these showers, then much drier air will begin to make its way to the surface. By Saturday morning, dew points will have tumbled from the 60s into the 40s and skies are very likely to become clear given the deep northwesterly flow indicated by all guidance in advance of a large area of high pressure. Seasonably cool and dry air will make for ideal leaf peeping conditions on Saturday.

KEY MESSAGE 2: High pressure slides across the Northeast CONUS and out toward the Canadian Maritimes early next week, giving us a dry finish to the weekend. A cold front crosses the region Sunday night into Monday. The best forcing with this system will remain to our north, but still expect scattered showers to be possible with the frontal passage. A colder airmass follows the front as high pressure returns for mid week. Tuesday looks to be the coldest day with highs only in the mid 40s to mid 50s, while overnight lows in the 20s to around 30F.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Through 00Z Friday...For the next several hours, mainly high clouds and some virga are expected as a decaying upper level system shifts just north of the region. Gradually increasing low-level winds and cloud cover should preclude fog development. The only potential exception will be localized IFR/LIFR possible in fog in the favored valleys in eastern VT, including KMPV. Probabilities from the NBM are sporting values of about 40-60 percent between 08z and 12z, and utilized a TEMPO for 2SM there for now. Light southerly winds increase and become more southwesterly in some spots with wind speeds 7 to 13 knots sustained with gusts 16 to 22 knots. As winds start subsiding around 20-21z, LLWS will be possible, mainly over KMSS and KSLK, which could spread east beyond 00z Friday. Additionally, some isolated rain showers may start reaching areas west of the Greens by about 20-22z.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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