Isolated Severe Thunderstorms Possible For Tuesday

Champlain Valley Weather Discussion:
     As of 11:55PM Doppler Radar has calmed down quite a bit from earlier, when we had all that rain. All that's left on radar right now are some very widely scattered showers. Not only did small streams, brooks, and small rivers rise to near or above bankfull, but a few of the large stem rivers (Missisquoi, Lamoille, and Passumpsic) had some significant within bank rises of 3-5 feet. Below is a list of rainfall totals for the rain we received today.

(Note: Some of these readings are from personal automated rain gauges, so some of the data may be slightly inaccurate. I will have a more detailed list once the CoCoRaHS reports come in tomorrow morning.)

Rainfall Totals:
North Troy-(Missisquoi River Rain Gauge): 2.55"
West Glover: 2.12"
East Berkshire: (Missisquoi River Rain Gauge): 1.66"
Elmore: 1.59"
Hyde Park: 1.44"
Worcester: 1.28"
Island Pond: 1.21"
St. Albans: 0.99"
Marshfield: 0.89"
Swanton Village: 0.85"
South Burlington: 0.69"
Plattsburgh: 0.45"
Beekmantown: 0.41"

     Now we will move on to tomorrow. An upper level low near the Great Lakes region will bring a round of showers and thunderstorms as the cold air aloft, will fight with the warmer surface air, and cause some instability. At this point it is still not certain how unstable the atmosphere will become. If we can get some breaks of sun tomorrow, for any extended period of time, then the atmosphere would be able to become more unstable then currently anticipated. Never-the-less breaks or no breaks of sun, showers, and thunderstorms are expected to develop in the afternoon, with some isolated severe storms possible in the mid afternoon to early evening time frame.

     Of most concern will be the potential for some localized flash flooding, especially across Central and Northern Vermont where widespread .75 to 1.5 inch, and isolated 2.0 - 2.5 inch rainfall totals occurred today. Flash Flood Guidance indicates that 1hr/3hr/6hr Flash flood values range from 1-3 inches across Northern and Central Vermont. With precipitable water values (PWATS) expected to be in the 1.2 - 1.6 inch range tomorrow, it wont take much to get a strong thunderstorm to drop that much rain within the 1hr/3hr/6hr time frame. With this in mind, on my suggested alerts map, I have issued a Flash Flood Watch for Chittenden, Franklin, Lamoille, and Washington Counties in Vermont. As of right now, there are no official alerts in effect from the National Weather Service in Burlington, Vermont. Please stay tuned for any further updates!!