Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
1147 am EDT Friday Oct 24 2014
upper level low pressure will pull slowly away from the region
today with morning showers or periods of light rain tapering off
as the day wears on. A brief period of dry weather is expected
tonight into Saturday...before more shower activity arrives
Saturday night into Sunday. Drier and warmer weather are expected
for the early portions of next week.
Near term /until 6 PM this evening/...
as of 1140 am EDT Friday...just finished a little belated late
morning update, but in general the overall forecast is in good
The deep moisture is departing, and based on web cams and surface
obs, there does not appear to be much more than spotty drizzle or
very light rain, and this is mainly across Vermont. On the other
side of the forecast area, skies are starting to clear out across
the St Lawrence Valley and as a result, temperatures are already
poking into the lower 50s there. For everyone else, low-middle 40s is
about all (except the highest peaks above 4000ft where
temperatures are running in the lower 30s with some light icing
happening since they are in the clouds).
For the rest of the afternoon, the improvement process is going to
be painfully slow for the eastern half of the region. Perhaps some
breaks in the clouds will make it as far east as the Champlain
Valley, but that won't be until just before sunset at the very
earliest. As a result, I knocked temperatures down a few degrees
from the Champlain Valley eastward as the clouds and continued
northerly flow will keep things on the cool side.
Short term /6 PM this evening through Sunday/...
as of 348 am EDT Friday...variable clouds then gradually trend
partly cloudy tonight as weak shortwave ridging skirts across the
area. Advective processes not all that strong and with at least
some lingering/patchy clouds around near seasonal lows ranging
through the 30s look reasonable at this time.
By Saturday into Sunday models remain consistent in showing rather
robust northern stream energy dropping east-southeast into our region with a
renewed threat of showers. Energy will arrive in two bundles...the
first occurring by Saturday evening and the second during the
daylight hours on Sunday. Latest nwp trends suggest better dynamical
support for precipitation to occur across the north later Saturday night and
especially into Sunday where ive offered a decent shot of showers
(50-70%). Quantitative precipitation forecast not all that heavy given Continental source region of
the feature...but a good bet that many areas will see a few showers.
The best day of the weekend will occur on Saturday as much of the
day will be dry out ahead of this system and where 925 mb thermal
forecasts support highs ranging through the 50s. By Sunday...arrival of
clouds and precipitation will Herald somewhat cooler temperatures (46 to 54). As
colder air arrives aloft through the day on Sunday...precipitation will
likely trend to snow above 3000 feet where some light accumulations
will be possible by days end.
Long term /Sunday night through Thursday/...
as of 348 am EDT Friday...low pressure continues to exit the
region Sunday night into Monday with an upper ridge building
eastward from the central Continental U.S. And surface high pressure
developing over the southeast. Cyclonic northwesterly flow
continues across the north country through Monday supporting some
lingering valley rain and mountain snow showers though mainly
confined to the higher elevations of Central-Northeast Vermont.
Temperatures will run right around seasonal values with lows sun/Monday
nights in the 30s and 40s...and highs Monday in the 40s and 50s.
Upper ridge builds across the northeast Tuesday while high pressure
over the southeast shifts offshore and low pressure develops
upstream over the western Great Lakes. Pressure gradient between
these features increases southerly flow across the northeast with
1000-500mb thicknesses rising to around 560dm Tuesday afternoon.
850mb temperatures rise to near +10c supporting highs well above normal in
the middle 50s to middle 60s under partly sunny skies. As the surface low
shifts northward from the Great Lakes to east of James Bay Tuesday
night into Wednesday morning...a thermally strong but moisture
lacking cold front tracks through the region. 00z runs of the European model (ecmwf)
and GFS are in decent agreement with frontal passage timing which is a bit
faster than previous runs. Based on current forecasts...cold front would
push through the area Wednesday morning with light quantitative precipitation forecast amounts
and temperatures falling sharply through the day under strong cold air advection.
Thereafter for the remainder of the extended period through Thursday
surface high pressure builds back into the region with zonal to
southwesterly flow persisting aloft. This will offer a generally dry
forecast with seasonal temperatures.
Aviation /16z Friday through Tuesday/...
through 12z Saturday...a mix of IFR to MVFR ceilings will persist
through most of today as moisture feed off the Gulf of Maine
continues to stream into the forecast area. Exception will be kmss
where VFR conditions will continue. Areas of drizzle and MVFR
visibility remain likely through 16z from kslk eastward as well.
Conditions begin to improve after 16z from west to east with a
sharp improvement in ceilings middle-late afternoon as low clouds
scatter out revealing middle/high VFR deck. All sites are VFR after
Outlook 12z Saturday through Tuesday...
12z Saturday - 18z Saturday...VFR under high pressure.
18z Saturday - 12z Monday...VFR trending to areas of MVFR in
valley rain showers and possible mountain snow showers as a cold
front brings colder air into the region.
12z Monday - 00z Wednesday...VFR under high pressure.