Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
343 PM EDT sun Aug 2 2015
a warm and increasingly humid air mass will move into the region
tonight and Monday ahead of a cold front. This cold front will
bring showers and thunderstorms to the region Monday afternoon and
evening. Some of the thunderstorms may be strong to severe along
with locally heavy downpours. Cooler and less humid conditions
arrive for the middle week period.
Near term /until 6 am Monday morning/...
as of 330 PM EDT...diurnally driven cumulus has developed within a middle
level Theta-E ridge axis advecting into the region. Current surface
dewpoint depressions across the region were between 20-30f so any
sprinkles/showers that may develop will likely not reach the
ground /virga/. The loss of daytime heating will likely dissipate
the cumulus field with a dry night expected and near seasonable
temperatures. Further upstream...a line of severe thunderstorms
has developed across Lake Huron and into southeast lower Michigan.
This is likely a signal for our upcoming weather during Monday.
Short term /6 am Monday morning through Tuesday night/...
strong to severe thunderstorms are possible Monday afternoon and
evening ahead of an approaching cold front.
Storm Prediction Center continues to highlight the region within the slight risk /15%/
with the 18z update and NCEP model suite continues to suggest an
active period of weather later Monday afternoon into Monday
evening. Impressive thermal warm advection in advance of the cold
front as h850 temperatures rise close to 20c Monday morning with filtered
sunshine due to the convective debris from diminishing convection
upstream. Strong surface heating well into the 80s and dewpoints
climbing into the lower and middle 60s will allow for increasing
instability. Sbcapes climb to between 1-2k j/kg...30-40kts 0-6km
shear and associated hodographs revealing cyclonic curvature
with the 0-1km...showalters dropping below 0c /mainly across
E-NY/...middle level lapse rates of 6.5-7.5 c/km and precipitable waters climbing
to an average value of 1.50 inches...scattered to numerous
thunderstorms are expected along and just ahead of the cold front.
Per coordination...we will place severe wording into the
grids/forecast from late afternoon into early evening. Initial
convective Mode will scattered-broken cellular structures /perhaps
supercellular/ before evolving into a scattered-broken line of convection
as lengthening hodographs will favor some long-lived cells and/or bows
capable of damaging winds and large hail /from Storm Prediction Center swody2/.
Since this will likely be a late event...question will be how much
will survive once it reaches portions of western New England and
especially into Litchfield County. Some of the high resolution
experimental reflectivity forecasts suggest a weakening trend for
these areas...however...we will continue to fine tune the
specifics with overnight updates.
In the wake of the frontal passage...a cooler and rather unsettled cyclonic
flow regime evolves with additional showers and storms possible
into Tuesday. In fact...if enough surface heating were to
commence...additional hail threat may develop as wet bulb zero
heights fall to around or below 10k above ground level. H850 temperatures fall back to
between 10-15c with h500 temperatures averaging around -15c.
Conditions should quiet down Tuesday night...with the exception
off Lake Ontario as those h850 temperatures continue to fall back into
the positive single digits...however...this too will increase the
low level lapse rates for some lake response for some showers to
impact portions of the dacks.
Temperatures will initially be quite warm-hot on Monday in
advance of the cold front with mainly 80s and perhaps touching 90f
in a few spots before the clouds/storms arrive. Then temperatures
slipping back to near to a bit below normal for early August the
remainder of the short term.
Long term /Wednesday through Sunday/...
a large trough will occupy the northeast Continental U.S. During this period.
Wednesday high pressure will be building into the region from the
Great Lakes...bringing a touch of the season to come. It will
be a bit cooler and less humid with highs 75-80 in the valleys...
lower to middle 70s higher terrain.
Due to cyclonic flow and cold air aloft...there could be a few
mainly afternoon instability showers...well north of I-90. Otherwise
it will be a mix of clouds and sunshine and perhaps a sprinkle even
It will be pleasantly cool Wednesday night with lows generally in
the 50s...with some middle or upper 40s in the coolest mountain valleys.
On Thursday....all the models now indicate a significant wave
will develop into a low pressure area well to the south of our
region. This low is forecast to track south and east of the region
much like a winter storm. Of course precipitation will be all
rain...and right now the rain shield could reach north to about
I-90 or even a little further north by early Friday. Thursday
looks as if cloud increase and a few showers could develop south
of Albany by late in the day. We increase probability of precipitation to 30 for now
everywhere by Friday and call it showers (although there is an
outside chance it could be an all day rain).
With clouds and chance of showers...highs will only be in the 70s
both days...and if the situation looks even wetter...we could be
talking about highs in the 60s for Friday. For now...kept it
closer to climatology and given it is not a slam dunk that rain
will overspread our region.
Low pressure moves out on Saturday...but a lingering upper level
trough could keep our weather a little unsettled (due to residual
low level moisture and cyclonic flow). For now...we just kept slight
chances in for Saturday and Sunday. Temperatures will continue to
average a bit below normal...upper 60s northwest to upper 70s
southeast with overnight lows generally in the 50s.
Aviation /19z Sunday through Friday/...
VFR flying conditions will prevail throughout the taf period
except for some potential late night MVFR visibilities associated
with mist at kpou and kpsf.
This afternoon...scattered to broken cumulus/stratocumulus will
prevail at the taf sites through much of the afternoon before
diminishing with loss of peak daytime heating this evening. Winds
will be out of the south/southwest around 10 knots.
Tonight into Monday...skies will become clear as high pressure
begins to slide east of the region...and a cold front approaches
from the Great Lakes region. Skies are expected to remain mainly
clear through 08/09z when scattered high clouds ahead of the
approaching cold front move into the region. Patchy MVFR
visibilities associated with mist/increasing low-level moisture
will be possible at kpou and kpsf between 08z-12z. Any MVFR
conditions will return VFR after 12z with scattered high clouds
and cumulus around 5 kft forming by the late morning.
Winds will generally be light and variable tonight...except for
southerly at kalb around 5-7 knots. Winds will be south/southwest
after 12z Monday around 10 knots.
Monday night: high operational impact. Likely rain showers...tsra.
Tue: moderate operational impact. Chance of rain showers...tsra.
Tuesday night-Thu: no operational impact. No sig weather.
dry conditions will continue through tonight and most of early
Monday morning before showers and thunderstorms develop on Monday
along and ahead of the cold front. Tonights relative humidity
values will rebound from the 25 to 45 percent this evening to 75
and 95 percent overnight.
It will be very warm and more humid Monday with minimum relative
humidities between 45 and 65 percent. Showers and thunderstorms
are expected Monday afternoon and evening as a cold front
approaches and crosses the region. Some strong to severe
thunderstorms will be possible along with locally heavy downpours.
mainly dry weather tonight into Monday morning with showers and
thunderstorms expected Monday afternoon and evening as a cold
front approaches and crosses the region. The storms will be
capable of producing locally heavy downpours as precipitable waters rise up to
around 1.5 inches ahead of the boundary. The heavy rainfall could
lead to some minor flooding in poor drainage and low lying areas.
Also some within bank river rises would be expected.
Isolated to scattered showers and thunderstorms are expected on
Tuesday especially during the afternoon as the upper level trough
axis approaches and passes over the region.
For details on specific area rivers and lakes...including
observed and forecast river stages and lake elevations...please
visit the advanced hydrologic prediction service /ahps/ graphs on
kenx Doppler radar maintenance is complete and have returned to
full operational Mode. Thank you for your patience.