textproduct: Burlington

WHAT HAS CHANGED

As of 225 AM EDT Monday...

The timing of precipitation on Wednesday has sped up.

KEY MESSAGES

As of 225 AM EDT Monday...

1. Seasonable conditions with nighttime fog early this morning and tonight.

2. Hotter weather will begin to build, but incoming precipitation on Wednesday will bring in the humidity.

3. Warm and humid conditions will continue into the later portion of the week with chances for showers and thunderstorms.

DISCUSSION

As of 225 AM EDT Monday...

KEY MESSAGE 1: After two days of soaking rain, especially north, widespread fog is being observed as surface high pressure builds overhead. Despite some breezy winds just off the ground, it has not stopped the fog from blossoming across the area. Take extra time commuting, and avoid using high beams. Allow additional space between yourself and other vehicles as well.

After sunrise (about 5am), fog will quickly dissipate, which should help keep impacts outside the heaviest commuter traffic. Seasonable weather conditions are expected today as moderation takes place underneath beautifully sunny skies. Very dry conditions will place relative humidity between 25-35 percent during the day, but there will be little wind to speak of. So we will again radiate out tonight. We'll likely observe fog more confined in space and time to more favored river valleys with pleasant lows in the mid 40s to mid 50s.

KEY MESSAGE 2: The upper ridge axis will shift east on Tuesday, and this will send temperatures upwards during the afternoon. The NBM 5.0 has been noted to have a modest warm bias, and so the forecast is keeping conditions in the 80s. Dewpoints will be on the rise as well, but it won't be anything too oppressive with lower to mid 50s during the day.

Otherwise, model timing on Wednesday's system has trended faster. An upper trough embedded within the high amplitude ridge pattern that has defined the last couple weeks will approach northern New York perhaps as early as Tuesday night. Precipitation will then spread east into Vermont mid to late morning. This faster arrival will impact daytime temperatures and will likely keep things in the mid 70s to lower 80s for most. This activity slides east overnight, but another system with an additional push of deep moisture will move east. So we may not lose showers completely with sunset as we head into Thursday. Fortunately, the amount of instability and forcing appears marginal. However, some embedded downpours in weak mid-level based instability of 100-200 J/kg are possible. The air mass will trend towards pea soup territory with precipitable waters climbing to 1.75-2.00". Thursday will be warmer, but again, pulled back the NBM 5.0's warm bias to reflect muggy conditions in the mid 80s to near 90.

KEY MESSAGE 3: Large scale mid to upper level ridging will breakdown late this week as a transient upper level low gradually tracks across southern Canada and the Great Lakes towards Friday. Shower chances look to increase into Friday afternoon associated with the upper low. There does appear to be good model consensus among the ensembles, and even more so amongst the deterministic models, of a cold frontal passage during the day Friday, though exact timing on Friday remains uncertain. The region looks to be in the right entrance region of a jet streak leading into Friday, which with a frontal passage colocated with peak heating could lead to some thunderstorm activity. Long range GFS model soundings show good dynamics present with the system. Limitations to the setup would be any convective debris that may linger from Thursday should convection fire in the Great Lakes. Temperatures Friday and into the weekend will be dependent on any shower activity, with 925mb temperatures around 20, supporting highs in the mid to upper 80s. With the approach of the Friday system, moisture will also be increasing with dewpoints in the low to mid 60s, drying slightly for the weekend into eh upper 50s. It will be a hot and muggy end to the week with overnight lows in the low to mid 60s, offering only a slight reprieve. Models become varied beyond Friday in terms of precipitation, with the GEFS denoting a hung up cold front, keeping moisture and shower chances into Saturday, and others like the ECMWF offering a transient front with drier conditions through the weekend.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Through 12Z Tuesday...Visible satellite this morning shows extensive river and valley fog across the entire region, though based on observations it is shallow only around 100-200 ft agl. Given how dense the fog is, with vsby reductions to 1/4SM in some locations, along with model soundings, fog may linger towards 13Z even with our early sunrise. Visibility improvements will likely occur around 12Z, with cig improvements following closely between 12-13Z. Once fog clears this morning, there is high confidence in VFR through at least 00Z tonight. Winds will be near calm with very light, under 5 knot, variable flow. A light lake breeze may impact PBG throughout the day with light SE flow, but otherwise remaining variable for all terminals. Winds trend calm tonight, with some signs of fog development again. Best chances for fog, which are low at the moment, will be at MSS/SLK/MPV with more sheltering and better chances to reach the crossover temperature.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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