Area forecast discussion
National Weather Service New York New York
739 am EDT Sat may 25 2013
Synopsis...
low pressure remains in the vicinity of the Gulf of Maine through
Sunday morning...then slowly lifts northeast into the Canadian
maritime provinces as weak high pressure builds into the region
through Monday...then settles to our south into Tuesday. A warm
front approaches from the southwest Tuesday night...then slowly
lifts to our north through Wednesday night. This front then stalls
out across northern New England through the end of the week as
high pressure builds back in to the south.
&&
Near term /until 6 PM this evening/...
minor adjustments made to the grids to reflect the latest trends
in observations and guidance. Forecast appears on track.
Closed low slowly lifts to the NE today...with probability of precipitation decreasing
from categorical from SW to NE through the day for occasional to
scattered -shra. With cold pool aloft transiting the area a low topped
thunderstorm cannot be completely ruled out...possibly producing
some graupel. However confidence is not high enough to reflect in
the forecast at this time.
Gusty northwest winds today in response to tight gradient around surface-850
low to our NE - but should remain just below advisory level with
gusts up to 35-40 miles per hour and sustained winds of 20-30 miles per hour. Note - if
stronger winds from 950-850 hpa in the GFS are realized (vice
winds 5-10 knots lower in the NAM/ecmwf) - then could see some
isolated gusts to Wind Advisory criteria especially across higher
elevations to the north and west of NYC.
For highs today used a blend of mav/met guidance with NAM 2-meter
temperatures and a mix down from 850 hpa per BUFKIT soundings.
Highs will struggle to reach from the upper 40s/around 50 across north
interior zones to the middle 50s across the NYC metropolitan. Would not be
surprised if some elevated locations across the interior stayed in
the middle 40s. These highs are some 20-25 degrees below normal.
There is a moderate rip of currents at Atlantic beaches today.
&&
Short term /6 PM this evening through Monday night/...
cutoff low continues to track to the NE with decreasing probability of precipitation from
SW to NE from tonight into Sunday. Most areas should be dry by
Sunday afternoon...but did linger slight chance probability of precipitation over NE 1/3
of the County Warning Area in deference to slower solution of the European model (ecmwf). Winds
will remain gusty...but will slowly diminish tonight and Sunday as
the cutoff pulls away - allowing for the pressure gradient to
slowly relax over the region.
For lows tonight used a blend of mav/met guidance and NAM 2-meter
temperatures with values around 10 degrees below normal. Winds
should be too strong for frost formation across northern interior
zones. On Sunday...used a blend of NAM 2-meter
temperatures...mav/met guidance blend...and a mix down from 800
hpa...for highs with readings forecast around 5 degrees below normal.
Deep layered ridging builds in Sunday night through Monday night
with diminishing winds and cloud cover...with dry weather.
For lows Sunday night used a blend of mav/met guidance and NAM
2-meter temperatures with values forecast 5-10 degrees below
normal...except near to slightly below normal in NYC. Winds should
once again be too strong for frost formation across interior zones.
For highs Monday used a blend of mav/met guidance with NAM 2-meter
temperatures and a mix down from 800 hpa per BUFKIT soundings.
Expect highs to be near normal - with possibly an afternoon sea
breeze developing if the pressure gradient relaxes as much as
currently forecast. Used a blend of NAM 2-meter temperatures with
mex/mex ensemble mean/ece/wpc guidance for lows Monday night - with
readings near to slightly below normal.
&&
Long term /Tuesday through Friday/...
European model (ecmwf) and GFS are fairly consistent through the long term...so
followed a blend.
Deep layered ridging continues to build in through the period. A
passing shortwave over the top of the ridge Wednesday will enable
a warm front to lift through the region...with the front stalling
out across northern New England through the end of the week. Have
slight chance probability of precipitation far west zones Tuesday afternoon then chance probability of precipitation
Tuesday night and Wednesday with the warm front...with a slight
chance of thunder Wednesday as the area gets into the warm sector.
Do linger slight chance probability of precipitation Wednesday night and Thursday as there
is some question how quickly the warm front clears to the north.
Depending on exact placement/strength of the ridge there is some
potential for diurnal convection to develop Friday...but
confidence in this is too low to reflect in the forecast at this time.
For temperatures Tuesday-Friday used a blend of mex/mex ensemble
mean/ece/ece ensemble mean/wpc guidance. Temperatures start out
near normal...but rise to above normal by Thursday and remain so
through the rest of the week.
&&
Aviation /12z Saturday through Wednesday/...
low pressure will deepen over the Gulf of Maine today.
Northwest winds ramping up during the day with frequent gusts reaching
30kt by 14-15z. Gusts then eventually increase to 35-39kt this
afternoon along with occasional gusts to 40-43kt possible.
Moderate to high confidence of a wind direction around 320 true.
Ceilings will generally be MVFR to start...then gradually increase to
VFR by noon. Some terminals may fluctuate between MVFR and VFR up
until then.
There is the potential for small hail in rain showers today with cold temperatures
aloft.
Outlook for 12z Sunday through Wednesday...
sun...VFR. Northwest gusts around 30 knots.
Monday...VFR.
Tue-Wed...MVFR or lower possible in the vicinity of a warm front
Tuesday night and Wednesday.
&&
Marine...
minor adjustments made to the grids to reflect the latest trends
in observations and guidance. Forecast appears on track.
Gale Warning will remain posted for all waters through tonight as a
northwest flow strengthens today. Might not be until around noon before
some of the waters reaches gale force gusts...and gusts over the New York
Harbor and Long Island bays could subside under 35 knots by midnight
tonight. Additionally...the Gale Warning might need to be extended
into part of Sunday morning over some of the waters as mixing
deepens again. Winds then aloft and at the surface subside on Sunday
afternoon...but with at least Small Craft Advisory conditions for a good portion of
the day.
All waters then fall below advisory criteria late Sunday/Sunday
night. This period of sub-Small Craft Advisory conditions then continues for Monday
and Tuesday with a relaxed pressure gradient keeping winds under 15
knots. Relatively tranquil conditions then look to continue into
Wednesday.
&&
Hydrology...
additional rainfall will be around 0.25 to 0.5 inch with locally
higher amounts possible through tonight. Locally heavy rainfall
through this morning could produce pockets of minor flooding of
poor drainage/urban locations.
No significant precipitation is expected from Sunday through at
least Tuesday.
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.
&&
Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...Gale Warning until 6 am EDT Sunday for anz330-335-338-340-345-
350-353-355.
&&
$$
Synopsis...maloit
near term...maloit
short term...maloit
long term...maloit
aviation...jc
marine...jc
hydrology...maloit
