Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
748 am EDT Thursday may 28 2015
a cold front will move through the region today bringing a chance
of showers. There is a chance for some thunderstorms this
afternoon across Vermont. A ridge of high pressure will build into
the region tonight and will remain over the north country through
Friday. A strong cold front will move slowly southeast from Canada
on Saturday. This cold front will bring a chance for showers and
thunderstorms Saturday and Saturday night.
Near term /until 6 PM this evening/...
as of 748 am EDT Thursday...composite radar loop showing showers
across the northern Champlain Valley with more shower activity
scattered over northern New York at this time. Previous forecast
looks in good shape at this time...so no changes have been made.
Previous discussion from 426 am EDT Thursday...composite radar
loop showing some rain showers over Eastern Lake Ontario and
western New York state at this time moving northeast toward the
Saint Lawrence valley and the Adirondacks ahead of a cold front.
Cold front to swing through the region today with drier air in the
form of lower dew points arriving into the region this afternoon.
Btv 4km model showing some convection developing across the
western slopes of the Green Mountains early this afternoon ahead
of the cold front. Btv 4km model has these storms east of the
Connecticut valley by 21z today. Storm Prediction Center has portions of eastern
Vermont in a slight risk for severe thunderstorms today.
However...not buying into this as cloud cover moving in ahead of
the cold front will likely limit amount of destabilization
today...with high temperatures mainly in the 70s today...so not
expecting any severe thunderstorm activity over the forecast area
today. The best chance for any severe weather today will likely be
east of the forecast area today.
Short term /6 PM this evening through Saturday/...
as of 426 am EDT Thursday...a ridge of high pressure will build
into the region tonight and will remain over the north country
through Friday...with fair and dry weather expected. Have gone a
bit warmer than MOS guidance for maximum temperatures on Friday under
full sunshine. A cold front will move slowly southeast from Canada
on Saturday. GFS model continue to be faster and more progressive
than the slower European model (ecmwf) model with this cold front. Thus...some
timing differences as to when precipitation will develop across
the region...with the best chance for showers and thunderstorms at
this time mainly Saturday afternoon into Saturday night.
Long term /Saturday night through Wednesday/...
as of 330 am EDT Thursday...little change from the previous couple
of forecasts for days 4 through 7. Still anticipating a surface cold
front to produce a line of showers and thunderstorms on Saturday
into Saturday night. Some uncertainty with regards to amount of
instability and timing of surface feature...along with potential
impacts from middle/upper level clouds on surface heating. Will continue to
mention likely to Cat probability of precipitation on Saturday night...with some potential
for strong to severe storms...depending upon amount of instability
present when frontal passage occurs. At this time...best instability looks
to be located across central New York into central/southern New England
with cape values between 1000 and 2000 j/kg...while best 0 to 6 km
deep layer shear is across southern Canada. Surface high pressure
builds into the area on Sunday...resulting in drier and cooler
weather for the start of next week. Some patchy frost is possible
in the colder mountain valleys on Monday morning. Highs will be below
normal on Sunday/Monday with readings in the 60s to near 70...but
warm to above normal levels by Wednesday with lows generally in
the 30s colder valleys on Monday morning to M/u 40s
Champlain/Saint Lawrence valleys. Lows warm back into the 40s and
50s by middle week.
Aviation /12z Thursday through Monday/...
through 12z Friday...mainly VFR conditions expected through this
morning...with brief periods of MVFR ceilings/visible associated with
showers moving across the dacks into the Champlain Valley. Expecting
additional showers/storms late this morning into the afternoon
hours today...with best chance of seeing brief MVFR conditions at
rut/mpv/btv. A few stronger storms will be possible near mpv/rut
with gusty outflow winds and frequent lighting. Otherwise...breezy
southwest winds at 10 to 20 knots will shift to the northwest
behind boundary this afternoon and become light toward sunset.Patchy
fog/br will be possible at mpv/slk and maybe Rutland...depending
upon measured rainfall today.
Outlook 12z Friday through Monday...surface high pressure with VFR
conditions develop Thursday night and Friday...before another
front with more storms occur on Sat afternoon into Saturday evening.
Some patchy fog/br is possible at mpv/slk and Rutland on Saturday morning.
These storms will contain localized gusty winds...brief heavy down
pours...and frequent lightning. Look for breezy south to southwest
winds at 15 to 25 knots to develop ahead of approaching surface
boundary on Saturday. A wind shift to the northwest will occur
behind the boundary on Sunday. Monday will be mostly dry with VFR