Area forecast discussion
National Weather Service New York New York
355 am EDT Thursday Jun 20 2013
Synopsis...
high pressure remains in control through Friday. The region will
then be in between a stationary front to the north and the Bermuda
high to our south and southeast Friday night through Tuesday. The
front begins to push south towards the tri-state as a cold front
on Wednesday.
&&
Near term /until 6 PM this evening/...
a large area of high pressure remains over much of the eastern
Seaboard with the center gradually shifting offshore through the
day...developing a S-SW return flow in its wake. This will keep
skies sunny through the day. A few flattening cumulus clouds will
develop through the day with afternoon heating and along the sea
breeze boundaries.
Sea breezes will have no problem developing today with a light
prevailing flow and light winds through the lower part of the
atmosphere. These will likely start earlier in the day with areas
along the coast reaching their high temperatures early.
Used a mav/met blend for temperatures as they were reasonable. Highs will
be near to just below seasonable values...upper 70s near the coast
with lower 80s inland and near the NYC metropolitan area.
&&
Short term /6 PM this evening through 6 PM Friday/...
high pressure remains in control through Friday with the center
pressing farther offshore and heights slightly building aloft.
General S-SW flow continues through Friday with afternoon sea breezes
developing again. Mostly clear skies continue with a few flattening
cumulus developing again.
Mav/met blend again was reasonable for temperatures. Lows will be allowed
to drop below normal with good radiational cooling
conditions...middle 50s to the lower 60s. Highs on Friday will be
very near Thursday temperatures...maybe a degree warmer.
Maintained a dry forecast for Friday afternoon even with models
trying to show a few showers. Instability with afternoon heating
could develop a shower or two over far north and west areas but
there is little in the way of a trigger or moisture and have left
the mention of any probability of precipitation out of the forecast.
There is a low risk for rip currents at Atlantic Ocean beaches on
today.
&&
Long term /Friday night through Wednesday/...
good overall agreement on general features over the region through
Tuesday...so followed a general blend of available guidance through
then. GFS and ecwmf then differ on how far S cold front penetrates
into Wednesday...so used a blend...as the 00z European model (ecmwf) has trended
towards the less progressive GFS solution with the front.
Weak 700-500 hpa ridging builds in Friday night...so it should be
dry. Used a blend of mav/met guidance for lows with temperatures
near normal in NYC and a few degrees below normal elsewhere.
700-500 hpa northern stream trough approaches Saturday
afternoon...then crosses the area Saturday evening. With best
forcing mainly to the north...limited slight chance probability of precipitation for rain showers/thunderstorms
Saturday afternoon/evening to the northern interior zones.
Otherwise...it should be dry across the tri-state Saturday/Saturday
night. For highs Saturday used a blend of NAM 2-meter
temperatures...mav/met guidance and a mix down from 925 hpa near the
coast...875 hpa well inland and 900 hpa in between. Expect readings
to be a few degrees above normal. For lows Saturday night used a
blend of mex/mex ensemble mean/ece/wpc guidance with values near to
slightly above normal expected.
The region will be on the northern periphery of a deep layered ridge
centered just off the southeast U.S. Coast Sunday-Tuesday. Multiple
shortwaves are prognosticated to work their way over the top of the ridge
from time to time Sunday-Monday night. Given that these are
inherently difficult to time this far out...just went with slight
chance probability of precipitation for rain showers/thunderstorms in the afternoon/evening mainly north of Long
Island.
The ridge then retrogrades to the west from Tuesday into
Wednesday...allowing for troughing to build into at least the NE
U.S. As a result have chance probability of precipitation northwest 1/2...slight chance probability of precipitation for
remainder except far southeast Tuesday afternoon...tapering off to dry by
late Tuesday night - due to diurnal nature. On Wednesday have chance
probability of precipitation throughout as cold front begins slow approach from the north.
For temperatures Sunday-Wednesday used a blend of mex/mex ensemble
mean/ece/wpc guidance. Temperatures will run above normal during
this time frame...and could possibly approach/exceed the 90 degree
mark Tuesday/Wednesday if slightly warmer GFS verifies.
&&
Aviation /08z Thursday through Monday/...
high pressure remains in place through the taf period.
VFR. Light SW to variable winds heading into the morning push. Local
sea breezes expected for all but kswf. Sea breezes start late
morning/noon before drifting north. Timing of sea breeze passage
could be off by an hour or two.
.NY 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)
Kjfk fcster comments: sea breeze could be an hour or two off.
Klga fcster comments: sea breeze could be an hour or two off.
Kewr fcster comments: sea breeze might not occur until around 21z.
Chance that sea breeze does not occur at all. If not...then winds
around 200 magnetic at around 10 knots through the afternoon.
The afternoon kewr haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.
Kteb fcster comments: sea breeze might not occur until around 22z.
Chance that sea breeze does not occur at all. If not...then winds
around 200 magnetic 7-10 knots through the afternoon.
Khpn fcster comments: sea breeze could be an hour or two off or
might not occur at all.
Kisp fcster comments: sea breeze could be an hour or two off.
Outlook for 06z Friday through Monday...
Thursday night-Fri...VFR. Prevailing SW winds.
Sat-Mon...mainly VFR. Areas of MVFR or lower in the morning. Isolated-scattered
afternoon/evening thunderstorms possible...especially north and west of NYC. SW winds.
&&
Marine...
high pressure remains over the waters through Friday setting up a
overall S-SW flow. Winds will remain generally 5-10kt with
occasional higher values Thursday-Friday afternoon. Seas will remain below
5ft through Friday as well.
Light pressure gradient over the region will keep winds 10 knots or
less Friday night-Saturday. Increasing SW flow will allow for winds
to increase to up to 15 knots on the ocean waters Saturday night and
Sunday and on all waters Monday. Small Craft Advisory level seas are not expected on
the waters through Monday.
&&
Hydrology...
no widespread significant rainfall expected through Friday.
There is the potential for isolated-scattered afternoon/evening
shra/tstms...mainly north/west of Long Island Saturday-Wednesday. While
most areas on any given day will not experience any
convection...given that precipitable waters are forecast to increase
to around/possibly higher than 1.5 inches starting on Sunday...there
is the potential for locally heavy rainfall with any stronger
convection from Sunday through Wednesday.
&&
Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...none.
&&
$$
Synopsis...maloit/ln
near term...line
short term...line
long term...maloit
aviation...jc
marine...maloit/ln
hydrology...maloit/ln
