textproduct: Burlington

WHAT HAS CHANGED

As of 235 PM EDT Sunday...

No significant changes.

KEY MESSAGES

As of 235 PM EDT Sunday...

1. Dry and seasonable through Tuesday

2. A brief intrusion of tropical moisture on Thursday will give way to seasonable, dry conditions heading into the weekend

DISCUSSION

As of 235 PM EDT Sunday...

KEY MESSAGE 1: An upper low will remain centered just to the east heading into tomorrow, keeping the region in a seasonably cool airmass. Skies will continue to clear as it inches to the east and by tonight, the clouds should be mostly gone. This will set the stage for efficient radiational cooling, with lows generally falling into the 40s and upper 30s. The current forecast low at SLK is 37, but it could easily fall a few more degrees if winds go calm early. Warm air advection will begin for Monday and Tuesday, but it will be unsuccessful in causing a significant airmass change, with the humidity staying low and temperatures remaining around seasonable values. A few showers are possible in northern areas Monday night and early Tuesday morning as a dying cold front passes into the region.

KEY MESSAGE 2: A very humid air mass will quickly advect into Vermont and northern New York late Wednesday into early Thursday due to channeled flow stretching across the Great Lakes into New England with 100+ knot flow at 300mb. Flow will be fast down at 850mb as well, though the intensity of the LLJ has backed off towards 40-45 knots. It will still result in a short duration of 2" PWATs across the region. Departing high pressure and the fast mid-level flow will result in fairly strong isentropic upglide. There should also be marginal CAPE of about 250 J/kg after dark on Wednesday for at least the St. Lawrence Valley (LREF ~40% > 250 J/kg, but expect that to percentage to increase as we get into the mesoscale model window). So moderate rain, perhaps briefly heavy, will race eastwards. Again, synoptic models are likely broad brushing rainfall amounts too much given the LLJ will produce west slope orographic enhancement and east slope terrain shadowing. The residence time of this moisture will be very short (5-9 hours) due to the fast flow, which will prevent significant rainfall totals. Broadly speaking, totals appear to range about 0.25-0.75", and we'll get towards the end of mesoscale models tomorrow for some of those finer details.

On Thursday, the tropical air mass will be gone, but there's still going to be a little moisture lingering. Marginal diurnally driven instability could produce a few showers Thursday afternoon, but it'll be generally warm in the 70s to near 80 while we await a cold front that'll pass through late Thursday night or Friday morning. Medium range guidance has shifted towards drier solutions for Friday. So we'll spend most all our weekend without rain as broad high pressure builds across the area. Some rain showers could begin approaching towards next Sunday evening when broad surface higher pressure will begin shifting offshore.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Through 00Z Tuesday...Surface high pressure is nosing into northern New York per latest analysis, but still notice a pres gradient between this high pres and departing low pres over eastern Canada. Sounding data shows 10 to 15 knots around 500 feet above ground level overnight, which could delay fog development at our climo favored sites. Have used tempo group to indicate IFR development between 05-08z at MPV/SLK with prevailing IFR/LIFR by 09z at both sites. Meanwhile, less confidence in fog development at EFK/MSS, so just used tempo to show potential near sunrise on Monday. Otherwise, rest of our taf sites stay VFR for the next 12 to 24 hours with northwest winds 5 to 10 knots, but gusts 15 to 20 knots on Monday afternoon.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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