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FXUS61 KBTV 032305 AFDBTV

Area Forecast Discussion National Weather Service Burlington VT 705 PM EDT Fri May 3 2024

SYNOPSIS
Dry and seasonably warm weather will continue across the region to start the weekend, with the exception of a few possible showers across northern New York on Saturday before widespread precipitation returns for Sunday. A period of warmer and sunnier conditions are expected for the start of the week, with more unsettled weather returning by the middle of next week.

NEAR TERM /THROUGH SATURDAY NIGHT/
As of 700 PM EDT Friday...A beautiful early May day acrs the North Country with temps in the mid 60s to lower 70s with mostly sunny skies. Upper air analysis and water vapor indicate mid/upper lvl ridge axis overhead, but weak short wave energy and mid lvl moisture is approaching the SLV. This has produced a broken area of light showers acrs western NY into the Ottawa Valley, with just light precip reaching the sfc. These light showers wl continue to slowly move toward northern NY tonight, with increasing chcs for light precip. Have continued with chc pops with a few hundredths of an inch of precip possible, not anticipating precip to reach CPV, as ridge holds firm.
Otherwise, temps cool back into the mid 40s to lower 50s with mostly light trrn driven winds, except northeast acrs the SLV and se at Rutland. No significant changes made to crnt fcst.

Previous discussion below: Surface high pressure and upper level ridging across the region haver made for a pleasant Friday afternoon, with dry conditions and seasonably warm temperatures. As we head into the evening, the upper level ridge axis will continue to shift eastward,although dry conditions will persist. There will be increasing high clouds across the region overnight associated with a frontal boundary to our west. Unlike the last few nights, increased clouds and winds will inhibit any fog development across the region. A light rain shower or two may be possible across northern New York early Saturday morning as the frontal boundary moves closer, but any measurable precipitation would be minimal. Overnight low temperatures will be mild, in the 40s to low 50s.

Saturday will be another pleasant day as we remain under the influence of high pressure, with mostly dry weather. Temperatures will warm into the 60s to near 70 in some of the broad valley locations, with high clouds remaining overhead. Dry weather will continue through most of Saturday night, with the latest guidance continuing to trend on the drier side for Saturday night with a strong ridge axis in place. Another mild night is expected, with temperatures in the 40s to low 50s ahead of approaching widespread precipitation on Sunday.

SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/
As of 303 PM EDT Friday...PWATs rise to around 1.5 standard deviations above normal on Sunday as moisture with Gulf of Mexico origin looks to overspread the region. Upper level pattern shows a stout omega block shifting east of our area into Maine, increasing shower chances and coverage on Sunday. However, organized convection is not expected as the main jet energy associated with the shortwave trough moving eastward from the Great Lakes is diverted into Quebec.
As a result, the main trough axis does not approach North Country until sometime next Tuesday. This will be discussed in the long term section of the forecast discussion. Indeed, forecast soundings show a lack of surface-based instability, so showers with brief locally heavy downpours look to be the main risk. While there could be embedded thunder due to elevated instability, no organized thunderstorms are anticipated.

PoPs do increase to the likely category with scattered to perhaps numerous showers on Sunday. While there would likely be widespread wetting rainfall, QPF amounts are quite manageable in the 0.1 to 0.3 inch range with locally higher amounts. Indeed, the MMEFS shows none of our area rivers going into action stage. Sunday will be quite a bit cooler than Saturday, with highs only in the 50s with low 60s possible if there are breaks in the rain or clouds. In addition, a 40-50 kt 925mb southerly low level jet overspreads the region on Sunday. NAEFS situational awareness ensemble table shows the v vector wind rising to almost 2.5 standard deviations above normal, so it will be breezy if not blustery. A mitigating factor is that the waters of Lake Champlain is still quite cold with water temperatures still in the low to mid 40s, which is almost isothermal to the forecast 925mb temperatures in the +5 to +8C range. That could reduce the mixing potential in the boundary layer. So have mostly kept wind gusts in the 30 to 35 mph range across the Champlain Valley despite the southerly wind component being anomalously strong. Overall, no overall hazardous weather to speak of but Sunday does look to be a less than ideal day for outdoor activities. Heading into Sunday night, showers taper off and the boundary layer looks well mixed enough to preclude widespread fog development. Temperatures stay quite mild in the mid 40s to low 50s.

LONG TERM /MONDAY THROUGH FRIDAY/
As of 303 PM EDT Friday...The overall weather pattern heading into the first full week of May can be described as unsettled with no real significant warm up or impactful weather. Unsurprisingly, the CPC 8-14 day temperature outlook favors near normal temperatures and leans towards above normal rainfall. For reference, typical highs for North Country in early May are in the low to mid 60s, while average overnight lows are in the mid 30s to low 40s. The upper level pattern features a positively tilted omega block sandwiched between an anomalously deep trough across the Rockies/northern Great Plains and another trough over eastern Quebec/Newfoundland. H5 height anomalies favor a period of widespread showers and thunderstorms in the Tuesday/Wednesday time frame, as positive H5 height anomalies give way to near normal values. Depending on the timing of the associated surface cold front, ingredients may exist for a few stronger storms. Taking a first look at ensemble guidance probabilities, it does look like the better chance for organized convection is across our southwestern zones, with more garden variety thunderstorms towards Vermont and the Champlain Valley. This makes sense from a synoptic perspective as the aforementioned positively tilted omega block may not be that easy to dislodge. As a result, our region only gets a piece of weak shortwave energy that peels off from the base of the northern Great Plains upper low and deamplifies as it tracks towards southern Ontario/Quebec. In simple terms, our region gets a glancing blow in terms of dynamical forcing and as a result, the odds for any stronger convective storms greatly diminish. While we are still 4 days away, model trends are favoring an unsettled but benign pattern for North Country in the upcoming week.

AVIATION /23Z FRIDAY THROUGH WEDNESDAY/
Through 18Z Saturday...VFR conditions prevail at all terminals this afternoon, and are expected for most of the forecast period.
Dry conditions are expected to prevail across all terminals, with increasing high clouds overnight. A stray shower cannot be ruled out across KMSS or KSLK as a frontal boundary approaches from the west, with some MVFR ceilings possible as well but there is a lot of uncertainty with any flight category reductions. Winds will be relatively light throughout the forecast period, generally less than 10 knots variable, becoming more southerly through the forecast period.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES
VT...None.
NY...None.

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