Area Forecast Discussion
Issued by NWS Burlington, VT

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305 FXUS61 KBTV 261127 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 727 AM EDT Mon Jun 26 2017 .SYNOPSIS... We will have a dry start to the day today...but scattered showers and isolated thunderstorms are expected this afternoon and evening. An even greater likelihood of showers and thunderstorms is expected on Tuesday. Temperatures will be several degrees below normal both today and Tuesday. The threat of showers will continue into Wednesday...but then a change will take place to a warming trend starting Thursday and continuing through the weekend. However...this pattern will also be conducive to more widespread showers and thunderstorms across the entire area during this period. && .NEAR TERM /THROUGH TUESDAY/... As of 727 AM EDT Monday...Going forecast in good shape and only tweak was to remove mention of any showers through mid-morning across the Northeast Kingdom as showers that were moving toward the area dissipated rather quickly in the past hour or two. And just a few tweaks to match current sky conditions and near term trends. Previous Discussion... Noticeable differences standout when comparing today to yesterday with respect to the convective potential. Today we are lacking the dynamic support as the shortwave trough that enhanced convection yesterday is moving northeast of the region this morning. No well defined dynamic support is expected across the area today. Cooler temperatures today will not allow for as much instability that developed yesterday and enhanced convection. Enough instability will develop to support convection...mainly scattered showers with only isolated thunderstorms. Deep layer shear has shifted just a bit to our south today versus being right over our area today. As a result...only looking at isolated to scattered showers today along with a few thunderstorms. Synoptic scale features and thermodynamic profiles do not support any storms becoming organized today. Highs today will only be in the mid 60s to lower 70s. Tonight...the showers and isolated storms lift northeast and most of the activity should be done by midnight. Lows will generally be in the upper 40s to upper 50s. Tuesday...Well defined shortwave trough moves out of the eastern Great Lakes and provide sufficient dynamic support for the development of showers and some thunderstorms. Colder air aloft will move into the region and despite highs only in the mid 60s to lower 70s...much like today...destabilization will occur and sufficient instability should develop for convection as 850-500 millibar lapse rates become dry adiabatic. These two elements should be enough to create more widespread showers than today and the idea of many areas having likely precipitation chances looks real good. If any storms do get organized on Tuesday...could see some small hail with them as wet bulb zero values will be on the lower side...much like on Sunday. && .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/... As of 450 AM EDT Monday...Overall convective activity should begin to wane Tuesday evening with the loss of surface instability but expect a few showers and thunderstorms to linger through the night as the driving mid/upper level shortwave trough passes through the region. It`s a fairly cold trough for late June so behind the feature temps will run about 5 degrees below normal across the board with lows in the 50s across the St. Lawrence and Champlain Valleys to mid/upper 40s elsewhere. Wednesday features a drier northwest flow behind the exiting upper trough with a mix of clouds/sunshine and temps seasonal in the low/mid 70s. Could see some terrain driven showers and perhaps a few thunderstorms with weak surface instability developing in the afternoon, especially across northern areas, but with the lack of any strong forcing aloft areal coverage should be low. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... As of 450 AM EDT Monday...Another active period of weather is expected for the end of the work week and through the weekend with the highlights being the potential for widespread and possibly heavy rain Thursday and again Saturday. Aforementioned upper trough exits the region Wednesday night with possibly the last dry night of the week before a fast westerly flow develops aloft for Thursday through Friday. Shortwave energy moving through the flow aloft combined with a warm front extended west to east from low pressure moving through the Great Lakes will provide the setup for widespread rain to develop along the boundary during the day Thursday. Instability is rather weak, and PWATs aren`t super high (1-1.5") so the heavy rain threat shouldn`t be widespread, but this event may prove to be the pre for potential hydro problems on the weekend. As the warm front shifts over the region Thursday/Thursday night it stalls with additional heat and moisture streaming into the region Friday night into Saturday on increasing southwesterly flow aloft with blocking high pressure anchored off Bermuda. While this is several days away, indications are for a return of 70 dewpoints and a plume of PWAT`s in excess of 2" presenting a heavy rain threat Saturday and Saturday night. Depending on what QPF falls through the week and especially on Thursday, flash flooding could be possible this weekend. Stay tuned. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... Through 12Z Tuesday...Overall looking at VFR conditions through the period. Areal coverage of showers will be isolated to scattered in nature and will be between 18z and 04z with just a low chance for thunder. Have indicated vicinity showers at all sites during this time period. Despite the showers...ceilings will generally be VFR through the period and visibilities for that matter too. Some MVFR ceilings may make it into parts of northern New York late in the period...generally after 06z. Winds will generally be under 10 knots through the period and will be from the west and southwest. Outlook... Tuesday: VFR. Chance SHRA...Slight Chance TSRA. Tuesday Night: VFR. Chance SHRA...Slight Chance TSRA. Wednesday: VFR. Breezy. Chance SHRA...Slight Chance TSRA. Wednesday Night: VFR. Slight Chance SHRA...Slight Chance TSRA. Thursday: VFR/MVFR. Chance RA...Chance TSRA. Thursday Night: VFR/MVFR. Likely RA...Likely SHRA...Chance TSRA. Friday: VFR. Chance SHRA...Chance TSRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Evenson NEAR TERM...Evenson SHORT TERM...Lahiff LONG TERM...Lahiff AVIATION...Evenson

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