Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
217 PM EDT Monday Jul 28 2014
a strong middle-Summer low pressure and upper disturbance will bring
rain and embedded thunderstorms to the north country today. The
rain will fall heavy at times resulting in gradual main Stem river
rises. A few strong storms could develop across eastern Vermont
during the afternoon hours. This system exits into Quebec later
tonight with leftover showers confined to the mountains. The middle
to latter part of the week features isolated afternoon showers
under cool temperatures aloft. Highs will be a few degrees below
normal through midweek...trending closer to normal by later in the
Near term /until 7 PM this evening/...
as of 215 PM EDT Monday...updated to include Severe Thunderstorm
Watch box #452 for central and southern Vermont. Latest laps show surface
based cape values have increased between 800 and 1200 j/kg across this
region. Thinking the best chance for strong to severe storms will be
across Rutland...Windsor...and Orange counties through early this
evening. No other change with this update.
Water vapor shows well defined dry slot across central/eastern
Vermont...with comma head moisture/lift across western/northern New York.
Watching potent 500 mb vorticity crossing southern/eastern New York at this time...which
has helped in the development of additional convection. This
convection will impact southern/central Vermont this afternoon...with strong
to potentially a few severe storms possible. Have updated to
mention gusty winds...small hail...and heavy rainfall across this
region this afternoon. Latest btv4 shows cape values between 1500 and 2000
j/kg...0 to 6 km shear around 35 knots...and lowering freezing/wet
bulb zero hghts as the closed 500 mb/7h approaches...supporting a hail
threat. Also...will continue to monitor potential for localized heavy
rainfall...especially across northern dacks associated with
deformation zones...and any heavier rainfall rates with stronger
convection over central/southern Vermont. Temperatures have jumped into the
70s with some breaks in the overcast near vsf...but are struggling
in the u50s/l60s across the dacks.
Short term /7 PM this evening through Wednesday/...
as of 415 am EDT Monday...
For tonight: prognosticated sub-1000 mb surface low lifts into Canada.
Moderate rain still expected early tonight but expect probability of precipitation to
generally decrease. A good signal for northwest upslope/blocked flow
showers (e.G. Sub-critical Froude numbers per 00z nam) keeps highest
probability of precipitation after midnight to the mountains. 850 mb temperatures fall to +7 to
+9c tonight and partial clearing should bring lows in the middle 40s to
Tuesday through wednesday: both days are fairly similar in terms of
sensible weather. Large-scale lift diminishes...with cyclonic flow and
cold air aloft producing diurnally-driven clouds/showers -
generally dissipating with loss of daytime heating. Slight chance
to chance probability of precipitation indicated...generally highest across the mountains
and across northern New York closer to upper troughing. Highs
generally in the upper 60s-70s Tuesday and Wednesday with upper 40s
to middle 50s for lows Tuesday night.
Long term /Wednesday night through Sunday/...
as of 415 am EDT Monday...a slow warming trend to near normal late
Summer temperatures is expected with partly sunny skies and an
average chance of an afternoon/evening shower or thunderstorm.
Models in good agreement that the upper trough weakens but remains
in place Thursday then retrogrades a few degrees westward over
the weekend. A building Atlantic ridge aloft, rising heights over
the East Coast with a Bermuda high strengthening at the
surface...which is fairly typical for late Summer...leaves US in a
weak but mild southwest flow aloft. Some small chance of showers and
thunderstorms will continue each after/evening as area remains locked into
the eastern side of the upper trough.
Slightly below normal maximum temperatures are expected Thursday with partly
sunny skies. High temperatures mainly 75 to 80 with 850 temperatures
around 10-12c. 850 mb temperatures warm a couple degrees 12-14c Friday and
little change expected over the weekend day should be 12-14c. With
partial sun under diurnal cumulus clouds expect highs moderating to
near normal - upper 70s lower 80s. Low temperatures will be generally in
the 50s to lower 60s trending milder over the weekend. Looks like
winds will be light through the period so River Valley fog is likely
as we move toward our our peak fog season.
Aviation /18z Monday through Saturday/...
through 18z Tuesday...a mix of flight conditions will continue
across the btv airspace over the next 12-18 hours...eventually
trending to VFR towards/after 12z Tuesday. As low pressure tracks
eastward across New York then northeast along a frontal system through
central New England to western ME/southern Quebec by 06z Tuesday
light to moderate rain will continue across northern NY/VT...with
thunderstorms developing across central/southern Vermont this afternoon.
Best chance for thunderstorms and rain will be at krut from 18-22z. Precipitation begins to
dissipate after 03z with MVFR/IFR trending to VFR after 12z where
thereafter diurnal cumulus will develop across the higher terrain.
North-northeasterly winds today trend towards the northwest later
today and eventually go light tonight before picking up again at
5-15kts from the west/northwest tomorrow.
Outlook 18z Tuesday through Saturday...
18z Tuesday - 12z Thursday...mainly VFR. Scattered showers with an isolated
thunderstorm possible Wednesday afternoon. IFR/lower visibility possible in
overnight fog/mist mpv/slk.
12z Thursday - 00z sun...mainly VFR although brief periods of MVFR
possible in an afternoon shower or thunderstorm.