Area forecast discussion
National Weather Service Albany New York
321 am EDT Wednesday may 22 2013
Synopsis...
low pressure will move from the Great Lakes region today into the
Saint Lawrence valley Thursday. Warm humid conditions will persist
into Thursday with showers and thunderstorms. Thursday a strong
cold front will push slowly through New York and New England. Low
pressure will form along this front on the coast Friday...as much
colder air pours into the region. Friday night the storm will move
offshore as high pressure builds into the Great Lakes region for
the Memorial Day weekend. It will bring fair weather with
unseasonably cool temperatures for the weekend.
&&
Near term /through tonight/...
line of thunderstorms east of I-88 corridor moving through fca
at this time. Mainly heavy rain and freq lightning. Areas of moderate rain
extend behind it.
Most areas to be impacted will see another 0.5 to 1.O inch of rain
bringing totals for today up to 2-3 inches in most areas impacted
with some isolated 4 inch amounts. Areal Flood Advisory has been
issued from mhwk valley and adjacent areas into S Vermont/Berkshire County
for overnight to cover any small stream and urban flooding.
This line should exit most of upstate New York/Vermont and west Massachusetts next 1.5 to
2 hours...except Catskills and middle Hudson Valley where it is just
arriving in areas that have not had much precipitation at all or since
since late Tuesday afternoon. It should then diminish and end overnight
At surface warm front is lifting NE through fca overnight and will be along
north tier or north of region Wednesday morning. It will move to St Lawrence Valley to
Michigan line...as weak low pressure forms along and propagates up
it today. This leaves fca in warm sector with alot of residual
low level moisture/clouds from Tuesday convection
With dew point in 60s...temperatures rebounding to 80s...variable clouds the threat
of thunderstorms increases through the day. Local WRF/hrrr which handled
todays event well...show a mainly cellular and pulse response
today in simulated refl. GFS produces surface convective available potential energy on the order of
1000-2000 j/kg the NAM 2000-4000 j/kg with a define preference
from the capital district S & east and the mhwk valley.
NAM and GFS show h850-700 lapse rates around 6.5 this afternoon.
Going to hrrr for the late aftn:
Pou/alb/gfl
cape 2000/1812/1777
j/kg maximum wind 33/33/40 ehi of 1.6/1.5/1.2
storm speed 24/18/18
srh 175/156/106
maglenta 1.75/2.17/2.44 all major severe
Which is considerably stronger looking than hrrr refl. The NAM
model soundings and WRF model soundings are considerably lower in
cape around 1000-1200 j/kg.
Precipitable waters will continue to run a few Standard deviations above normal
with values of 1.50-1.8 inches.
Some other considerations low level jet at h850 hpa is 25-35kts...and
bulk of it may pass west of fca. There is little additional upper
forcing. Storm Prediction Center has outlooked New York portions of fca at this point will
not try to get specific...will go with enhanced wording today. If
theres a preferred area it would mhwk valley and S...and a preferred
time of later in the afternoon and evening.
Convection will continue into the evening hours and dim overnight as
fca is firmly in warm section. Lows and dew point will be in the
60s...and areas of patchy fog possible in the morning.
&&
Short term /Thursday through Saturday night/...
Thursday and Thursday nt 500hpa trough starts moving east through Great Lakes as surface
low organizes along semi-stalled front from from Lake Erie up St
Lawrence Valley. This system pushes slowly east dragging a cold front to
btv-syr line Thursday afternoon...and through fca by 12utc Friday. NAM/GFS in
pretty close agreement with this timing. While there is increasing
dynamics with approaching jet and trough...convective available potential energy 1000-1500 ...
will be widespread holding maximum temperatures to middle 70s to around 80. Storm Prediction Center has
only put area in see text at this time...with low probs due to limited instability.
Regardless area will see period of -shra/thunderstorms increasing Thursday...transitioning
to -shra/-ra behind the cold front overnight.
By Friday morning cold front will be in I-95 corridor along the Atlantic
coast. 500hpa trough will be moving into NE USA...and both models
develop a modest surface low over New Jersey. The warmth of past few days
will give way to a cool breezy with -shra Friday. Finally surface low
moves offshore Friday nt as high pressure builds into the Great Lakes.
However the 500hpa trough lingers and cuts off over new eng Sat.
Between these two systems a brisk northwest gradient will drive some
pretty cool air into the region for late may. With 500hpa cut off
lingering skies may only be plus Sat in GFS.
Temperatures will probably go nowhere Friday...only coming off morning lows
a few degree...or holding steady.
The weekend forecast is deteriorating...
the GFS is progressive with surface low departing the coast Friday
nt...with its 500 hpa trough crossing region Sat and departing Sat
nt with pc skies and a rather brisk wind gradient.
The 00utc European model (ecmwf) cuts off the 500hpa low over New Jersey...develops a
coastal low...which lingers along the East Coast for the weekend
with periods of raw chilly rain.
The GFS temperatures would bring mins Sat morning into the middle 30s to
middle 40s with some near 30 and potential frost/freeze issues in
adrndks. Highs Sat will only rebound even with the strong sun to
the 60s. Lows Sat night would again be in the 30s. Winds will
remain brisk. European model (ecmwf) would result in slightly warmer night time
temperatures and cooler yet daytime temperatures in middle 50s to low 60s. HPC
leans toward a blend with chance probability of precipitation lingering into Sat. It will be a
fall like Memorial Day weekend.
Will lean toward GFS/HPC blend through Sat. At this time will make no
changes beyond Sat nt to minimize flip flopping given the spread
in models solutions at this time.
&&
Long term /Sunday through Tuesday/...
Canadian high pressure will build into the region Sunday. The high
will shift eastward across the region and offshore early next
week. Temperatures will gradually moderate as the high shifts to
the east with near seasonable temperatures for Monday.
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.
&&
Aviation /07z Wednesday through Sunday/...
accounting for current shower and thunderstorm activity that should
continue at kgfl through about 06z...at kalb through about
07z-08z...and kpsf through about 08z. Some MVFR and occasional IFR
conditions in the showers and thunderstorms. Some other isolated
thunderstorms well west of the area could approach the area between
kalb and kpou through sunrise...but with continued stabilization of
the atmosphere the thunderstorms could dissipate by then.
Once the rain ends early this morning...there could be periods of
MVFR fog and VFR ceilings...but scattered clouds could develop below
1000 feet. Will have to monitor for any better clearing toward
sunrise that could result in IFR fog and/or ceilings below 1000
feet. For now not indicating any IFR conditions at any taf sites
through the early morning hours...but will amend if conditions and
trends change.
VFR conditions should prevail through most of the day after 12z
until new convection develops later in the afternoon and evening.
Mixed signals about where the concentration of thunderstorms will be
later today so putting vcsh in all tafs after 22z...but more
thunderstorm activity expected scattered across the region late
tomorrow afternoon and evening.
Winds should be light south through sunrise...then become variable
at less than 10 knots through the day tomorrow...mainly south to
southwest. Winds should be light again tomorrow evening. Winds could
be quite gusty in thunderstorms tomorrow afternoon and evening.
Outlook...
Wednesday...VFR/MVFR. Chance -shra/-tsra especially during the afternoon.
Wednesday night...VFR/MVFR. At kgfl and kalb -shra/-tsra likely. At kpsf
and kpou chance -shra/-tsra.
Thursday...MVFR with IFR possible. -Shra/-tsra likely.
Thursday night...VFR/MVFR. Chance -shra/-tsra especially in the evening.
Friday...mainly VFR. Chance -tsra mainly in the am.
Sat-sun...VFR. No sig weather.
&&
Fire weather...
no fire weather concerns through Friday. Occasional showers and
thunderstorms will continue through Thursday night. Showers will
continue into Friday.
Relative humidity values will increase to 85 to 100 percent tonight...and
Thursday night...and lower to 45 to 60 percent this afternoon.
Winds will mainly less than 10 miles per hour through tonight...becoming
southwest around 10mph Thursday.
&&
Hydrology...
precipitable waters on the order of 1.5 to 2.0 inches next few days. While
widespread flooding is not anticipated...locally heavy rainfall in
thunderstorms and training could result in small stream and urban
flooding overnight and again this afternoon. Significant within
bank rises are likely in larger rivers.
3-hour zonal ffg values are generally in the 2.5-3.0 inch range at
this time...which are high for middle to late may.
Due to the scattered nature of the showers and thunderstorms...
basin average quantitative precipitation forecast will be highly variable this week. The best
threat for seeing significant amounts of showers or thunderstorms
will this afternoon into Thursday night.
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 our website.
&&
Aly watches/warnings/advisories...
CT...none.
New York...none.
Massachusetts...none.
Vermont...none.
&&
$$
Synopsis...Snyder
near term...Snyder
short term...Snyder
long term...iaa
aviation...NAS
fire weather...Snyder
hydrology...Snyder
