Area forecast discussion
National Weather Service New York New York
753 am EDT Friday may 24 2013
Synopsis...
a cold front moves across the area today. As the front tracks across
the area...a wave of low pressure will develop along the front and
slowly tracks to the Gulf of Maine by Sunday morning. This low will
then lift into the Canadian Maritimes through Monday. High pressure
then builds into the south through Wednesday night. A warm front
will approach on Thursday.
&&
Near term /until 6 PM this evening/...
forecast on track this morning with no significant updates. Some
patchy dense fog is possible across eastern Long Island and
eastern coastal Connecticut. The fog is not widespread enough for
a dense fog advisory so will issue an Special Weather Statement to address this.
The heavy rainfall threat has come to an end this morning as a
250hpa jet axis slides east of the region.
A cold front will enter the region today and slowly move from west
to east throughout the day. Additional showers are likely throughout
the day today. In addition to the showers...the possibility exists
for isolated thunderstorms along/ahead of the front after
daybreak. As the front moves across the region...winds will shift
from the south to the west...and eventually northwest. With the
front moving slowly...it may not be until very late in the day
that eastern parts of the County Warning Area see the wind shift.
A low pressure system will develop along the front and lift north
across the region. This will keep categorical probability of precipitation in the forecast
through the day today.
Followed a blend of mav/met guidance for highs today. Maximum
temperatures will range from the lower to upper 60s...with the
warmest temperatures across the eastern half of the County Warning Area...and
coolest across the western half. Temperatures will generally fall
through the day...except across the eastern half of the County Warning Area...where
temperatures will rise through midday...then fall with the passage
of the front.
There will be a high risk of rip currents today along the Atlantic
facing beaches of Long Island.
&&
Short term /6 PM this evening through 6 PM Saturday/...
the front continues to slowly slide east with a surface low passing
east of the area. Meanwhile...as the middle and upper level trough
moves over the area...a closed low develops. This should allow any
of the precipitation to transition from showers to more of a
stratiform rain. Model guidance in good agreement with probability of precipitation
continuing through tonight. Probability of precipitation will remain likely/categorical.
Once again...followed a mav/met blend for overnight lows.
Temperatures will fall into the 40s and 50s...with the warmest
locations across the far eastern portion of the County Warning Area...and the
coolest across the western. This will be due to cold air filtering
in on a northwest flow behind the front.
&&
Long term /Saturday night through Thursday/...
GFS/NAM/ECMWF all reasonably close in their intensity and movement
of the closed low and associated low pressure moving slowly NE this
weekend. Likely/categorical probability of precipitation expected everywhere once again on
Saturday. North-northwest winds on the back side of the low should become
rather brisk by Sat afternoon...falling just shy of advisory
criteria at 15-25 miles per hour with with gusts between 30 and 35 miles per hour into
early Sat evening. Can not rule out some gusts to near 40 miles per hour
either. In addition...there is a low chance of a thunderstorm over
eastern CT/Long Island via some elevated destabilization as dry slot
punches in from the SW. Will leave out of the forecast for now with
low confidence. Temperatures will be rather cool for late may...with highs
only 55-60 and dropping into the 40s Sat night.
Steady rain should shift east and taper off in intensity Sat night
as the low pulls east of New England...becoming more showery/isolated in
nature on Sunday via cyclonic low level flow and passage of
transient middle level vorticity maxes pinwheeling around the upper low.
Still cool and breezy on Sat with highs only upper 50s/lower
60s...and gusts 25-30 miles per hour.
Dry weather and a gradual warm-up to near seasonable levels is then
forecast Monday-Wednesday as high pressure moves across. Temperatures on Thursday should
return to more Summer-like levels with the approach of a warm
front...which could bring afternoon showers and possible thunderstorms
mainly to areas west of NYC.
&&
Aviation /12z Friday through Tuesday/...
cold front passes through this morning and slowly moves east
through the day.
Winds veer to the northwest by middle to late morning...and increase. Then for
the afternoon...northwest winds 15-20kt with gusts 25-29kt.
Low confidence with flight categories. Some VFR ceilings to start...then
MVFR moving in by late morning.
New York metropolitan enhanced aviation weather support...
Detailed information...including hourly taf wind component forecasts can
be found at: http:/www.Erh.NOAA.Gov/zny/n90 (lower case)
Kewr fcster comments: timing of MVFR might be off by an hour or two.
Frequent gusts might not begin until 18-19z. Winds mostly south of
310 magnetic until around 13-14z...then north of it thereafter.
The afternoon kewr haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.
Kjfk fcster comments: timing of MVFR might be off by an hour or two.
Frequent gusts might not begin until 18-19z. Winds mostly south of
310 magnetic until around 15z...then north of it thereafter.
Klga fcster comments: timing of MVFR might be off by an hour or two.
Frequent gusts might not begin until 18-19z. Winds mostly south of
310 magnetic until around 14z...then north of it thereafter.
Kteb fcster comments: timing of MVFR might be off by an hour or two.
Frequent gusts might not begin until 18-19z.
Khpn fcster comments: tempo bkn004 might not occur this morning.
Timing of MVFR might be off by an hour or two.
Kisp fcster comments: tempo bkn004 might not occur this morning.
Timing of MVFR might be off by an hour or two.
Outlook for 06z Saturday through Tuesday...
Friday night...MVFR/VFR. Showers. Northwest gusts 20-25kt.
Saturday...VFR. Showers. Northwest gusts 25-30kt.
Sunday...VFR. Chance am showers. Northwest gusts 30-35kt.
Monday through Tuesday...VFR.
&&
Marine...
have issued a dense fog advisory for the eastern waters. Fog has
developed and reduced visibilities to less than 1 mile. The dense
fog advisory runs until 11am. Patchy fog is possible on the
central ocean waters and portions of western Long Island Sound.
Small Craft Advisory remains up for the ocean waters through at least Friday night
as a lingering swell likely keeps seas up over 5 feet over a good
portion of the ocean waters. Gusts to 25 kts will be possible as
well during parts of this period on the ocean waters. Non-ocean
waters through Friday should see gusts peak at around 20 knots...but
a few gusts to 25 knots cannot be completely ruled out.
Northwest flow on the back side of the low as it moves into New
England...should strengthen gusts to gale force Sat
afternoon/evening. Have put up a gale watch for the ocean
waters...as well as the eastern sound and Peconic and gardiners bays
for Saturday and Saturday night. For the remainder of the
waters...have went with a Small Craft Advisory where gusts may fall
just short of gales. It is possible where the small craft is on
Saturday and Saturday night...gales may be needed.
Conditions fall back to Small Craft Advisory conditions late Saturday night and
continue on all waters into Sunday afternoon...then gradually taper
off on the ocean and then eastern sound/bays Sunday night. Quiet
conditions expected Monday-Tuesday via building high pressure.
&&
Hydrology...
on average an additional 1/10 to 1/4 inch of rainfall west...and
1/4 to 1/2 inch east...this morning ahead of a cold front. For the
most part...small stream levels have stabilized this
morning...with only minor rises expected in the wake of any shower
activity.
An additional 1/2-3/4 of inch of rainfall is expected from this
afternoon through tonight - with locally higher amounts possible.
Precipitable waters do decrease to under 1 inch by late Friday
night. As a result...the risk of minor urban/small stream
flooding looks to be minimal.
Basin average quantitative precipitation forecast of 1/2 to 3/4 inch expected Sat into Sat night...then
only minimal quantitative precipitation forecast in lingering showers on Sunday.
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...Small Craft Advisory from 6 am Saturday to 6 am EDT Sunday for
anz335-338-345.
Dense fog advisory until 11 am EDT this morning for anz330-340-
350.
Gale watch from Saturday morning through late Saturday night
for anz330-340-350-353-355.
Small Craft Advisory until 6 am EDT Saturday for anz350-353-
355.
&&
$$
Synopsis...BC/Goodman
near term...British Columbia
short term...British Columbia
long term...BC/Goodman
aviation...jc
marine...BC/Goodman
hydrology...Nevada
