Area forecast discussion
National Weather Service Albany New York
1021 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 has been allowed to expire for
Herkimer...Hamilton...Montgomery...Fulton...Warren...Saratoga and
Washington counties.
The concern for the overnight is the convection over eastern Great
Lakes and across eastern PA and central New York and the potential for
heavy rainfall with some portions of the forecast saturated from
heavy rains Tuesday night and Wednesday afternoon. Precipitable
water values from albany's 00z sounding is 1.51 inches and buffalo's
1.48 inches. The hrrr-3km 15 minute composite reflectivity is
handling the current convection placement and intensity pretty
well. Have used this for probability of precipitation and timing into the early morning
hours. The convection is expected to weaken as it moves east
mainly after midnight and we are seeing some signs of this. Have
showers likely with scattered thunderstorms with heavy rainfall
and gusty winds. The Storm Prediction Center has much of forecast
area in slight risk...may mention of strong storms in our
hazardous weather outlook.
&&
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 /02z Thursday through Monday/...
variable conditions overnight. Thunderstorm threat will prevail
for the next couple of hours...as lingering daytime instability
continues to fuel these storms. Have included tempo groups at
kgfl/kalb to account for any remnant thunderstorm activity.
Elsewhere...the threat for vcsh will remain throughout the night
as showers/thunderstorms approach from the western New York/mid-Atlantic
region. A combination of saturated low-levels and recent rainfall
should allow for MVFR ceilings/visibilities to develop at all taf
sites during the overnight hours. Kgfl/kpou may briefly dip to IFR
levels towards daybreak but confidence remains on the lower side
at this time.
The threat for showers/thunderstorms will increase during the day
Thursday as renewed daytime heating commences...with expected
scattered to widespread thunderstorm coverage by the early afternoon
hours. Flying conditions Thursday will fluctuate between VFR/MVFR
with periods of IFR associated with shower/thunderstorm activity.
Have introduced low level wind shear into the tafs through the overnight period as a
low-level jet passes overhead with light southerly surface winds
generally less than 5 knots. These southerly winds will increase
slightly during the day Thursday to 5-10 knots...with the potential
for higher gusts associated with any thunderstorms.
Outlook...
Thursday-Thursday night...MVFR with IFR possible. -Shra/-tsra likely.
Friday...mainly VFR. Chance -tsra mainly in the am.
Sat-Mon...VFR/MVFR. Chance -shra.
&&
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...iaa/okeefe
short term...okeefe
long term...iaa
aviation...irl
fire weather...okeefe
hydrology...Snyder
