textproduct: Burlington

WHAT HAS CHANGED

As of 229 PM EDT Tuesday...

Rain chances have lowered and trended quicker to end on Friday.

KEY MESSAGES

As of 229 PM EDT Tuesday...

1. Quiet weather, then showers and some thunderstorms remain likely Thursday afternoon and evening as a cold front moves through the region.

2. Dry weekend and some showers early next week.

DISCUSSION

As of 229 PM EDT Tuesday...

KEY MESSAGE 1: Aside from lingering light rain in southern Vermont, possible very localized showers late this afternoon in the western foothills of the Adirondacks, and fog development in the typical locations late tonight, there is little weather to speak of through Thursday morning. Following a cool start to the day, abundant sun and light winds will result in efficient warming tomorrow. As 925 millibar temperatures warm a bit relative to today, near 21 to 23 Celsius, we should see highs in the mid to upper 80s in most locations. Tomorrow night with increasing clouds and a bit more near surface west/southwest winds bringing in more humid air, we will not be quite as cool to start the day on Thursday.

The latest guidance for Thursday's expected showers appears to be in fairly good agreement in this forecast cycle, where a weak front draped west to east develops right over the region during the afternoon and slowly shifts southward. In a marginally unstable environment, driven off of increasing moisture convergence in a higher PWAT environment, cells will tend to develop on the north side of this boundary rather than south. This pattern with very dry air aloft south of the boundary suggests warm sector coverage of convection will be quite limited. At this time, there appears to be a relatively narrow threat area closer to the International Border during the afternoon and first part of the evening, shifting southward with time into the Adirondacks and central Vermont by evening. The Storm Prediction Center currently shows a general thunder risk, which seems reasonable considering the small overlap area of 1000 J/kg of CAPE and 30-40 knots of bulk shear near the front (greater shear north, greater instability south). Still think a storm or two could reach severe wind levels in this environment, but the risk of this is low. Similarly, there is no Excessive Rainfall Outlook at this time; antecedent dryness and only a small ribbon of anomalous deep moisture points to only brief heavy rainfall associated with any stronger thunderstorms in northernmost portions of New York and Vermont.

Have noted that with this front sinking southward and little additional shortwave energy passing through Thursday night, precipitation will tend to become lighter or even diminish as it moves into southern Vermont. In general, the risk of showers, and especially heavy rain, for July 10th is low with these trends as cool northerly flow brings our humidity back down during the course of the day Friday. Perhaps southern portions of Vermont will have enough lingering heat and humidity to spark a thunderstorm, but trends in the data are suggesting Friday is mainly a dry day for our region; expect PoPs will trend lower.

KEY MESSAGE 2: This weekend will be dry both in terms of precipitation and humidity, with no rain expected and low humidity. Temperatures will be seasonably warm, with highs in the upper 70s and 80s. Lows overnight will be relatively comfortable, in the 50s to around 60. The heat and humidity begin to build in for the beginning of next week, but a cold front looks to come through before they can become fully established. It will be accompanied with a round of showers and potential thunderstorms, but the exact timing and extent of the precipitation remain uncertain. This is the typical July setup where the potential for strong to severe storms will be watched, but it will be conditional on factors like the exact timing of the frontal passage, the strength of the synoptic forcing and the amount of instability that will be able to develop ahead of it. However, the the front does look to be relatively strong for the time of year, with the potential for a notably cooler airmass on the backside.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Through 00Z Thursday...Conditions are VFR at this time. Patchy fog development is expected in climo favored spots like KMPV and KSLK, but also at KRUT since it received rain into the afternoon. Overall, highest confidence is in KMPV, and noted prevailing 3SM with a 1SM TEMPO from 07z-11z, and will monitor trends overnight. Any fog that forms lifts by 12Z and VFR conditions will persist through tomorrow. Light or terrain driven flow is expected, tonight, and will favor southwest to northwest after 12z, followed by a shift to southwest or south beyond 22z. Wind speeds will be about 4-8 knots through the period.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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