textproduct: Burlington

WHAT HAS CHANGED

As of 247 AM EDT Monday...

Winds have been increased for Tuesday afternoon, but otherwise no significant changes were made with this forecast package.

KEY MESSAGES

As of 247 AM EDT Monday...

1. Widespread rain this morning will end by this afternoon, with warmer and drier conditions expected through Tuesday. Tuesday will also be breezy with gusts of 25 to 40 mph possible along the international border.

2. Low chances of showers and seasonable temperatures expected for mid week.

3. Below normal temperatures and some showers are likely late in the week before conditions trend dry and warmer.

DISCUSSION

As of 247 AM EDT Monday...

KEY MESSAGE 1: Much like yesterday, a swath of light to moderate rain is spreading over the region early this morning. This precipitation will continue to push eastward through the morning hours as a surface trough/boundary likewise moves eastward. Moisture converging along/ahead of the trough has resulted in PWATs exceeding 1.25 inch, and with warm cloud depths around 10 kft, rainfall processes should be pretty efficient as this rain moves through. Indeed, note that are pockets of moderate to even heavy rain embedded within the broader area of precipitation, with some spots reporting a quarter to upwards of a third of an inch of rain in an hour. While the front is slow-moving, it will make enough forward progress to limit any flooding threat beyond ponding of water in poor drainage areas. The rain still looks to exit to our east by early afternoon; total rainfall amounts through that time should generally be in the 0.50 to 1.0 inch range, with locally higher amounts possible where heavier rain lingers. The St Lawrence Valley will remain on the northern fringe of the rain, so rainfall there will be closer to a quarter of an inch.

Drier air will follow the trough/boundary, and expect we'll end up with a fairly nice afternoon under partly to mostly sunny skies. Highs will be much warmer than yesterday as we'll top out in the mid 60s to mid 70s. This warmer and drier trend will carry over into Tuesday. High pressure centered just to our south will allow for lots of sunshine, fair weather, and highs in the upper 70s to mid 80s. A cold frontal boundary will approach from Canada late in the day, but any showers associated with this will hold off until dark. A 45+ kt 850 mb jet ahead of this front will move over northern areas Tuesday afternoon, and with steep low level lapse rates resulting in efficient mixing, winds will likely become quite breezy, especially in the St Lawrence Valley and along the northern Adirondacks. Gusts of 30 to 40 mph will be possible in these areas Tuesday afternoon. Elsewhere, gusts should remain 20 to 30 mph.

KEY MESSAGE 2: Upper low pressure will slowly pivot across eastern Canada and the Maritimes Wednesday through Thursday, keeping us under northwest flow. A series of upper shortwave troughs and surface boundaries/fronts will rotate around the upper low, bringing occasional chances for showers through mid week. These features are hard to pinpoint in timing, placement, and intensity, so really can't say for that any one day will be dry vs another, so have gone with 15-30% PoPs for much of the Wednesday through Thursday timeframe due to the uncertainty. Regardless, any showers that do develop should remain scattered and fairly light in nature. We do anticipate the start of a cooling trend; while highs on Wednesday will be in the 70s to near 80F, Thursday will be noticeably cooler with temperatures remaining in the 60s in most spots.

KEY MESSAGE 3: No big changes to the forecast rationale for late in the week into the weekend as an upper level trough digs southward into our region before slowly kicking to our east, supporting cool and mostly cloudy conditions. The global ensemble mean shows this upper level low and associated greatest 500 millibar height anomalies (per AIGFS as low as the climatological 2nd percentile) overhead Saturday morning and then weakening/migrating to our east thereafter as anticyclonic flow develops. As such, the period in which this trough is either upstream or overhead will provide us with at least scattered to numerous showers due to strong synoptic scale lift, especially if a surface cold front sharpens coincident with the system. PoPs remain in the chance category due to uncertainty in timing/location of this trough, but the pattern looks favorable rain to occur at some point, especially on Friday and Saturday. The latest cluster analysis reflects the timing uncertainty. Two of the four upper air patterns, making up the majority of ensemble membership, show similar progression of anomalous 925 millibar temperatures and precipitation chances, but high 6 hourly probabilities of rain are offset by about 12 to 18 hours. While chances of rain decrease on Sunday, per some of the latest guidance showing a very slow exit of the trough rain cannot be ruled out this far out in time.

AVIATION /06Z MONDAY THROUGH FRIDAY/

Through 06Z Tuesday...Expected changeable flight conditions due to fluctuating ceilings and intensities of rain as a plume of widespread showers gradually shifts eastward over the airspace through the morning. Moderate rain with embedded heavier elements will affect all sites except for MSS, for about two to four hours within the 06Z to 12Z period with otherwise light rain intensity. Additionally, upstream observations and model soundings suggest within lighter rain ceilings could lower, especially with decreasing winds towards 12Z. While all sites will likely have temporary IFR conditions, greatest chances of prevailing IFR ceilings appears to be at sites including MSS, SLK and RUT. Winds will be largely light as the precipitation-inducing front moves through. Breezy conditions with about 10 to 15 knots of southeasterly winds at RUT will diminish as precipitation expands over the terminal. As drier air moves in from the west between 12Z and 18Z and clouds scatter soon after, winds will gradually shift westerly and increase into the 7 to 10 knot range, then trend southwesterly after 00Z.

Outlook...

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

BTV WATCHES/WARNINGS/ADVISORIES

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