Area Forecast Discussion
Issued by NWS Burlington, VT
Issued by NWS Burlington, VT
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492 FXUS61 KBTV 301639 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 1239 PM EDT Sun Jun 30 2024 .SYNOPSIS... Humid air ahead of a cold front will help supply enough fuel for scattered morning thunderstorms. Some storms may be capable of a few strong to locally severe wind gusts and flash flooding. Chances of thunderstorms will decrease during the afternoon as drier air begins to enter the North Country, and precipitation chances will diminish tonight. Quieter weather is expected for the upcoming week with seasonable warmth and mostly rain-free conditions. && .NEAR TERM /THROUGH MONDAY/... As of 1232 PM EDT Sunday...Biggest change with this update was to temperatures. With ample sunshine, they`ve soared well into the 80s across much of VT, while NY spots are in the mid/upper 70s. This is already above previously forecasted highs by 3-5 degrees, and have increased maximum temperatures for this afternoon accordingly. Otherwise, the rest of the forecast remains in good shape. We continue to see isolated to scattered convection popping up along the pre-frontal trough, with the bulk of the activity having been in the northern tier of counties along the international border. Storms have not been overly impressive so far, with updrafts getting sheared apart before being able to gain much appreciable height. We will continue to monitor closely, but so far the main threat has been torrential rainfall; saw one rain gauge near Franklin, VT that recorded nearly an inch in less than 30 minutes. Any strong/severe storms would be capable of producing damaging winds, as evidenced by strong cells that have been crossing southern NY over the past couple of hours. Please remain weather aware today, especially if you have outdoor plans. Previous discussion...A strong and complex frontal system will progress through the northeastern US today. At the moment, we are in the warm sector with ample heat and humidity, but because of the nocturnal timing, instability is pretty low, especially in Vermont. In northern New York, particularly in St. Lawrence and Franklin counties, there is notably higher instability. This environment should support thunderstorm development in the pre- dawn hours as outflow from a cluster of showers in Ontario approaches, providing necessary lift to grow existing showers, which are being hampered by mid- level dry air. Given ample effective shear and downdraft CAPE, organized thunderstorms will be capable of isolated, damaging wind gusts, so we will be focused on the morning convection over the northern counties of our region as it moves across northern New York and Vermont. Following this, there will be one more opening for impactful weather associated with a pre-frontal trough, between 8 AM and about 1 PM. There will likely be at least some sunny breaks in the sky, allowing for temperatures to warm into the low 80s across much of Vermont to boost instability. Coverage of thunderstorms remains questionable given the drying aloft, but any cells will also be capable of damaging wind gusts with similar parameters given high deep layer shear and DCAPE. Generally the threat will shift southeastward during this time frame. Then this evening we will see winds back to the northwest, supporting lowering humidity following some scattered showers along and just behind the cold frontal passage. Low temperatures should be about seasonable in the upper 40s to near 60. Dry weather is expected tomorrow. With continued cold air advection and the related northerly breezes, temperatures tomorrow will end up actually a little below normal, mainly in the low to mid 70s. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/... As of 324 AM EDT Sunday...Surface high pressure building into the region with a cooler, drier airmass with low temperatures in the 40s/L-M50s. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... As of 324 AM EDT Sunday...Really no changes from yesterday`s perspective...High pressure still in control on Tuesday with moderating temperatures to near or slightly above seasonable levels with highs in the U70s-L80s. Tuesday night will feature upper ridge axis across the NE and dampening with the approach of a northern stream shortwave with the surface high shifting SE for the development of a return SSW flow and temperatures back into the M50s-L/M60s. Northern stream shortwave shifts east across southern Canada which will dampen further the heat ridge across the southern CONUS. A warm front traverses the area Wed with increased heat/humidity but likely decent amount of clouds which may limit instability. Pre-frontal trof may try to move during or shortly after peak heating so can`t rule out showers and t-storms late Wed then front Wed eve especially in northern NY possibly holding off in VT until around/after any firework celebrations but stay tuned. as there are some firework celebrations Wed eve. Highs in the upper 70s-M80s with dewpoints back AOA 60F. Upper level shortwave rotates east across southern Ontario/Quebec thus the cold front slowly moves across CWA but appears to wash out across the area. Therefore showers overnight Wed night with a leftover morning shower possible on the 4th. Otherwise, despite a lingering boundary there appears to be lack of any lift or instability and should be mainly dry or only a shower for Independence Day festivities with temperatures in the U70s-M80s. Another northern stream shortwave/trof moving across the upper Mississippi Rvr Vly Friday lifts ENE across the northern Great Lakes and weakens Friday night and takes a similar path across SE Canada Saturday. Weak low pressure associated with it will follow suit but the lingering boundary will attempt to lift across our area as a warm front Friday night-Saturday for some shower activity but not a repeat of yesterday. Also right now, I`m leaning toward mainly dry for Friday. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... Through 12Z Monday...Aside from SLK where ceilings are as low as 1200 feet, VFR conditions are present this morning with isolated showers primarily in northern New York. Following some daytime heating, showers and thunderstorms will become more likely ahead of a pre-frontal trough through about 16Z. Still have relatively higher chances across the SLK-PBG-BTV area through this period. A direct hit would support brief heavy rain and IFR conditions, but mainly VFR/MVFR conditions are expected to continue. Winds mainly 5 to 10 knots have already trended westerly; they are primarily southwesterly this morning and expected to become westerly this afternoon, and then northwesterly towards 00Z. The northwesterly winds will be accompanied by additional shower chances along with lowering ceilings, with MVFR conditions most likely at SLK and EFK overnight. Outlook... Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. NO SIG WX. Tuesday Night: VFR. NO SIG WX. Wednesday: VFR. Slight chance SHRA. Wednesday Night: Mainly VFR, with local IFR possible. Chance SHRA, Slight chance TSRA. Independence Day: Mainly VFR, with local IFR possible. Slight chance SHRA. && .HYDROLOGY... The threat for localized heavy downpours and isolated flash flooding continues across our region through midday. We`ve generally seen between 0.75" and 1.5" of rain over the last 24 hours. Sharp river rises of the East Branch of the Passumpsic in East Haven and the Lamoille River in Johnson occurred overnight, indicative of hydrophobic soils. Therefore, scattered heavy showers and thunderstorms this morning will be capable of flash flooding in portions of northern Vermont today. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Kutikoff NEAR TERM...Hastings/Kutikoff SHORT TERM...SLW LONG TERM...SLW AVIATION...Kutikoff HYDROLOGY...Clay/Kutikoff