Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
145 am EDT Wednesday may 6 2015
a ridge of high pressure will build across the north country
overnight...lasting right though the week. Mostly sunny
skies...above normal temperatures and dry conditions will continue
through Friday with associated fire weather concerns. Conditions
then turn more unsettled into the weekend which offers the next
chance for precipitation for the north country.
Near term /until 7 am this morning/...
as of 124 am EDT Wednesday...forecast in good shape...so just
some minor changes made. Satellite loop showing high clouds that
were over the region have mainly moved southeast of the region at
this time...with mostly clear skies now over the region.
Short term /7 am this morning through Thursday night/...
as of 324 PM EDT Tuesday...main message in this period is high
and dry, as high-amplitude middle-level ridge builds in aloft.
Sensible weather conditions pretty similar each day and night,
with mostly clear skies producing sizable diurnal ranges with
abundant daytime sun and sharp cooling at night. Winds will
generally be light and largely terrain/lake- breeze driven as
well. The primary concern in this period will be the continued low
relative humidities and extremely dry fine fuels making the north
country susceptible to wildfires. For more specific details, see
our fire weather section below.
Thermal fields warm by a couple degrees each day, up to around
+10 to +11c at 850 mb by Thursday. We should mix to this level at
least, but likely even higher than that. After upward adjustments
to highs due to sunshine and dry soil moisture conditions, looking
at highs into the 70s by Wednesday and then the upper 70s/spot 80
degrees on Thursday, with lows in the 40s Wednesday night and the
upper 40s-low 50s Thursday night. From a moisture perspective,
still have a Good Reservoir of 925-700 mb drier air to mix down,
but guidance forecast soundings show progressively higher moisture
in this layer each day. It means dew points aren't likely to fall
quite as much as we've seen over the past couple of days. So
afternoon min relative humidity levels should stay in the 20-30
percent range through the period, due to roughly offsetting
effects from warming air temperatures and gradual rise in dew points.
Long term /Friday through Tuesday/...
as of 327 PM EDT Tuesday...seasonably mild to warm weather with
uncertain rain chances as we progress from Friday Onward into this
weekend and beyond. Most problematic will be eventual location of
a semi-stationary east to west oriented surface front and chances
for showers/scattered thunder in the Sat-Monday time frame with this
morning's models showing the boundary setting up anywhere from
southern New England to southern Canada. With the overall strength
of western Atlantic ridging, it would seem a more southerly
solution would tend to be an outlier at this point and have leaned
conservatively toward a blend of available guidance. Indeed, if
you believe this morning's Canadian global and European model (ecmwf) output the
front will have a hard time making it much past the international border.
This setup appears to have merit given the aforementioned Atlantic
ridging and some sort of sub-tropical development along the
southeastern Seaboard during this time frame. Regardless, have
offered chance probability of precipitation in the Sat-Monday time frame with at least a
nominal threat of scattered thunder Saturday afternoon. Highest values
mainly across our central/northern counties. Prior to that, quite
a warm day on tap for Friday as mean 925 mb temperatures average around
+20c under partial to full sunshine and a deeply mixed planetary boundary layer to near
750 mb. Thus maximum temperatures solidly in the 80s appears reasonable with
middle-upper 80s possible in the Champlain/St Lawrence valleys.
Cooling back slightly by Saturday into Monday but remaining above
By next Tuesday models come back into agreement showing more
robust energy ejecting east from the midwestern states. This
system will bring a more widespread threat of showers to the
region along with cooler, more seasonal temperatures. After all,
normal high temperatures are in the lower to middle 60s this time of
Aviation /06z Wednesday through Sunday/...
through 06z Thursday...VFR conditions will prevail at all sites
through 06z Thursday. Winds will become light terrain driven
overnight...before slowly shifting to the southwest during the
daytime hours. Expect a lake breezy to once again develop at pbg
with southeast winds between 5 and 10 knots.
Outlook 06z Thursday through Sunday... VFR conditions will
prevail through Sunday with exception of brief MVFR visible/ceilings in a
passing shower Sunday. Winds will generally be from the
south/southwest at 5 to 15 knots through the time period...with some
localized terrain effects at pbg and Rutland.
as of 124 am EDT Wednesday...weather conditions will continue to
remain favorable for fire weather through the rest of the week.
Light winds are anticipated through Friday, which will preclude a
red flag condition across Vermont and northern New York. However,
minimum afternoon relative humidity values will still fall into
the 20 to 30 percent range. In addition, one- and ten-hour fuels
are already extremely dry due to several days of sunshine and a
lack of precipitation (under two tenths of an inch from last
night's frontal passage). Further drying of these fuels will
continue to take place, and with these conditions, fire weather
concerns will linger into Friday. Statewide burn bans are in
effect for the state of Vermont until may 19, and remain in effect
for the state of New York until may 15.
as of 318 PM EDT Tuesday...boaters should keep in mind that water
temperatures remain cold - in the 40s. Swimming early in the
season is discouraged as immersion for prolonged periods of time
could produce hypothermia given these water temperatures.