Area forecast discussion
National Weather Service Albany New York
433 PM EDT Wednesday may 22 2013
Synopsis...
a cold front will slowly approach the region into Friday. Periods
of showers and thunderstorms will precede the front. The rain will
be heavy at times. Cooler and showery conditions will persist
into the first half of the Memorial Day weekend.
&&
Near term /until 6 am Thursday morning/...
..Severe Thunderstorm Watch 210 in effect until 10 PM...
Main band of convection and associated severe weather and flooding
rainfall continues to progress east. Some reports of wind damage
in Schenectady and Schoharie counties. Meanwhile...heavy
rainfall...radar estimate shows 2-3 inches has led to urban
flooding in Schenectady County.
With mesoscale convective system-like system continuing to track northeast through the
late afternoon severe threat/flash flood threat will continue east.
Attention will turn to activity for later this afternoon and
tonight. Currently to our West Lake breezes are forcing isolated
thunderstorms and rain. Hrrr shows lake breeze to Blossom with convection into later
this afternoon and evening as larger scale ascent translates
eastward from lower lakes. Instability has recovered across
western County Warning Area with mesoanalysis shows convective available potential energy in 1500-2000 j/kg range.
Bulk shear will remain favorable for severe storms with values
into the 30-40 knot range. Will carry enhanced wording to coincide
with watch...then scattered rain showers/thunderstorms and rain through remainder of overnight as
wait to see how convection evolves.
&&
Short term /6 am Thursday morning through Friday night/...
cold front slowly approaches the region on Thursday...not clearing
County Warning Area until Friday morning.
Slowly moving front will provide environment for bouts of heavy
rain through the period. Precipitable waters remain in the 1.5 inch range
through Thursday...only slowly dropping off into Friday.
Approaching upper level jet tomorrow brings right rear quadrant into
forecast area for the afternoon. See Hydro section for discussion
on flood risk.
Severe potential tomorrow is not clear cut now. Model cape looks
to be in the 1000 j/kg range with bulk shear respectable in the
30-40 knot range. Middle level lapse rates are relatively weak at
5.5c/km. Storm Prediction Center has region in see text. From today/S Vantage Point
that looks appropriate.
With cold front moving through on Friday...some diminishing in
precipitation expected for part of Friday. However GFS and European model (ecmwf) coming
into agreement on cut off migrating slowly from Delaware-Maryland-Virginia into New
England into the Holiday weekend. This will keep the threat of
rain/showers in the forecast for Friday. With County Warning Area on cool side of
surface low track...instability looks near none. So no mention of
thunderstorms and rain for Friday.
Mins on Saturday morning in Adirondacks are forecast in middle 30s.
This would mean threat of frost given beginning of the growing
season there. Will depend on clouds and precipitation.
&&
Long term /Saturday through Wednesday/...
model guidance has trended to a wet start to the Holiday weekend
along with chilly temperatures due to more cloud cover.
The model guidance has come into fairly good agreement that an area
of low pressure will form on the cold front just off coast near Cape
Cod as short waves move through the longwave. An upper level low is
expected to develop over the middle Atlantic region Friday night with
additional short waves maintaining this upper low with it moving
gradually northward up the coast. The low along the boundary will
slow the front's eastward progress and throw rain showers and clouds
back across New England and eastern New York state Saturday. The
region will remain under cyclonic flow through the weekend with
upper ridging not expected to begin to build in until Tuesday. At
the surface...high pressure should begin to build in Monday and
especially Tuesday. It appears the high should hold on for Wednesday.
As for temperatures...chilly. Temperatures are expected to run 10 to
15 degrees below normal Saturday and again Sunday. Brisk and gusty
northwesterly winds will only add to the chill. Temperatures are
expected to moderate toward seasonable levels Monday with the help
of sunshine but still be below normal by around 5 degrees.
The growing season is underway across the middle Hudson Valley...
greater capital district...Lake George Saratoga region...the Mohawk
Valley...eastern Catskills...Taconics...Berkshires...Bennington and
eastern Windham counties Vermont and Litchfield County. It will start on
may 25th for the southern Adirondacks and western Windham County.
Nighttime lows over the weekend are expected to be in the 40s with
30s across the higher terrain. With the expansion of the growing
season by this time frost advisories might be needed. Conditions
will be more favorable for frost Sunday night/Monday morning and
Monday night/Tuesday morning.
&&
Aviation /19z Wednesday through Monday/...
VFR prevailing with periods of MVFR for the balance of the
afternoon. Scattered -shra and thunderstorms and rain will directly affect or be in
the vicinity of the airports from the start of the taf period
through at least 22z. Clouds will be hard to clear
out...particularly the high-level CI/cs...which should limit
instability and the proliferation of ts. High dewpoints overnight
will result in some hazy fog...mainly MVFR...with a period of IFR
fog poss at kpsf where winds through the column will be lighter.
With little change in the environment expected into early
Thursday...MVFR conditions are expected to prevail at the airports
into the early afternoon hours...with more ts activity is
likely...though perhaps not until after the end of the taf period.
Expecting a period of marginal shear during the early night except
at kpsf...35 knots should be about it. Surface winds will hold up
overnight at less than 10 knots...picking up to speeds on Thursday
averaging slightly higher than today.
Outlook...
Thursday PM and night...MVFR with IFR possible. -Shra/-tsra likely.
Friday-Friday night...mainly VFR. Chance -shra/-tsra...mainly in the am.
Sat-sun...VFR. No sig weather.
&&
Fire weather...
no fire weather concerns into Saturday. Periods of rain...moderate
to heavy at times will continue into the Holiday weekend.
Relative humidity values will increase to 85 to 100 percent tonight...and
Thursday night...and lower to 45 to 60 percent Thursday afternoon.
Winds will generally be south at 5 to 10 miles per hour.
&&
Hydrology...
European model (ecmwf) and GFS very aggressive in bringing heavy rainfall into County Warning Area
into the Memorial Day weekend. Operational European model (ecmwf) and GFS produce
5-7.5 inches of rain in County Warning Area into Sunday. Gefs show average of 2.25
inches through weekend with 4 members pushing in excess of 3
inches. While not quite ready to accept totals of Euro and
GFS...enough guidance available to at least warrant potential of
heavy rain threat in severe weather potential statement. First challenge for heavy rain will come
tomorrow with slowly moving front. Eastern County Warning Area and central County Warning Area
have seen heaviest rain over the last two days and would appear to
be the region where flash flood threat is at highest.
Will monitor closely for at least potential of flash flood or
Flood Watch Thursday into weekend.
&&
Aly watches/warnings/advisories...
CT...none.
New York...none.
Massachusetts...none.
Vermont...none.
&&
$$
Synopsis...okeefe
near term...okeefe
short term...okeefe
long term...iaa
aviation...elh/wasula
fire weather...okeefe
hydrology...okeefe
