Area forecast discussion
National Weather Service New York New York
1245 am EDT Tuesday may 21 2013
Synopsis...
a warm front north of the area will sink south closer to the area
later today...then lift back north as a warm front on Wednesday.
A warm and humid air mass will remain over the area until a cold
front moves through Thursday night. High pressure will return for
the weekend and early next week.
&&
Near term /until 6 am this morning/...
broken to scattered stratus remains over Long Island from near
Islip and east. Fog bank south of Long Island still expected to
expand northward tonight. Will continue with the dense fog advisory
although delayed dense fog in forecast per observation/ Sat imagery.
Do not expect much change in temperatures overnight from current
readings...mainly lower 60s.
&&
Short term /6 am this morning through 6 PM Wednesday/...
frontal boundary will remain to the north on Tuesday as ridge prevails
across the northeast ahead of upstream trough...then drop S into
southern CT and perhaps eastern Long Island Tuesday night. The front
should be preceded by diurnal convection mainly inland late Tuesday
afternoon and early evening...then a general chance for showers
and isolated thunder later Tuesday night.
Tuesday should feature more sunshine than today after morning fog
Burns off...and with are more firmly entrenched in the warm sector
expect highs in the 80s inland and along the North Shore of western
Long Island...and 70s in coastal CT and the rest of Long Island.
Low clouds and fog should redevelop Tuesday night...mainly later at
night as it will take blyr longer to cool down closer to
dew points.
&&
Long term /Wednesday night through Monday/...
models coming into better agreement about the main features of the
week. Long term starts out with upper riding over the area with
a Midwest trough beginning to phase with a Canadian trough. A warm
front will be to the north of the area by Wednesday...extending from
a low pressure area over the Midwest.
A warm southerly flow sets up behind the warm front...allowing temperatures
on Wednesday to warm to above normal values. There is a wide range
of high temperature values on Wednesday...NAM 2m temperatures has highs in the lower 90s
out west...which could possibly be due to differences in cloud
cover. Have leaned toward the warmer met...not as warm as the
NAM...with highs in the middle 70s to middle to upper 80s. Lows
will be slightly above normal.
Also on Wednesday...with the moist southerly flow near the warm
frontal boundary...thunderstorms are possible. Ml and surface cape west
of NYC will be reaching above 1000 j/kg in the afternoon along with
decent low level lapse rates. Even with the front nearby...lift may
not be strong enough to generate any widespread thunderstorms. Any
thunderstorms that do develop may produce heavy rain with precipitable water above
1.5 inches. Only have chance probability of precipitation in Wednesday as there is some
discrepancy on the timing of the precipitation approaching the area and the
coverage of it.
Deep trough then develops over the Midwest on Thursday and tracks
east with the associated low pressure tracking NE into Canada and
dragging a cold front south of it. Cold front approaches Thursday
evening with a pre frontal trough developing ahead of it...once
again triggering scattered showers and thunderstorms. Instability will be
slightly less that Wednesday but better lift will be evident. Still not
expecting anything severe but may see strong storms that Wednesday. Do
have likely probability of precipitation in for Thursday afternoon and evening as models are
in good agreement of the timing of the rainfall. Temperatures will be
cooler than Wednesday...a few degrees above normal.
The trough moves east and rain ends west to east by Friday afternoon
with high pressure building in its wake and winds shifting to the
northwest. Memorial Day weekend will be dry with temperatures right at
normal. Highs will will be in the upper 60s to lower 70s Fri-Mon.
Lows will be in the middle 40s to lower 50s.
&&
Aviation /06z Tuesday through Saturday/...
warm...moist air will overspread the region tonight...resulting in
widespread fog/stratus through Tuesday morning.
Fog beginning to develop with patchy MVFR visibilities. Going through the
evening...fog should continue to develop and thicken. With very
warm and humid air pushing north from off the ocean...will expect
widespread fog to develop between 06z-07z. Delayed onset of
widespread fog by a couple of hours...as widespread fog is slow to
develop.
Conds gradually improve to VFR by midday Tuesday.
Outlook for 00z Wednesday through Saturday...
Tuesday night...becoming IFR with fog and stratus.
Wed-Fri...scattered showers/tstms. At night...IFR possible
with stratus/fog.
Sat...VFR.
&&
Marine...
seas remain below 5 feet...so have cancelled Small Craft Advisory for hazard seas.
Dense fog is expected and advisory remains through the morning.
The dense fog could last on the ocean into Tuesday night or Wednesday
morning.
Seas and southerly winds will increase on Wednesday via a tightening
pressure gradient. Seas could be above 5 feet by Wednesday
afternoon...with 25 knots wind gusts possible on the ocean waters by
Wednesday evening. A cold front will move across late Thursday night...with
high pressure building in at the surface on Friday. Winds could be
below Small Craft Advisory criteria by early Friday morning...with seas remaining
above 5 feet through Friday afternoon. Some uncertainty exists on the
timing of the cold frontal passage and the increase of winds on Wednesday.
&&
Hydrology...
isolated to widely scattered showers or thunderstorms late in the day Tuesday...mainly
inland. Impacts will be minimal.
Scattered showers/thunderstorms Wednesday-Thursday will be capable of producing locally heavy
rainfall...with the best chances north/west of NYC. Total basin
average quantitative precipitation forecast for Wednesday-Thursday could be 1/4 to 1/2 inch...with locally higher
amts in thunderstorms.
&&
Okx watches/warnings/advisories...
CT...dense fog advisory until 10 am EDT this morning for ctz009>012.
New York...dense fog advisory until 10 am EDT this morning for nyz071-
078>081-177-179.
New Jersey...none.
Marine...dense fog advisory until noon EDT today for anz330-335-338-340-
345-350-353-355.
&&
$$
Synopsis...Goodman/ln
near term...Goodman/pw
short term...Goodman
long term...line
aviation...mps
marine...Goodman/ln/pw
hydrology...Goodman/ln
