Area forecast discussion
National Weather Service New York New York
1243 am EDT Thursday Jun 20 2013
Synopsis...
high pressure remains in control through the end of the week. As
high pressure remains anchored across the western Atlantic
Ocean...a series of weak low pressure troughs will pass across the
region through Wednesday.
&&
Near term /until 6 am this morning/...
forecast on track tonight. Updated temperatures and dew points for trends
but no major changes were made.
Excellent radiational cooling conds due to clear skies...a dry
airmass...and nearly calm winds will continue. Temperatures will quickly
drop into the 50s away from NYC. Lows tonight will drop to the
upper 50s in/around NYC...and in the upper 40s to lower 50s most
elsewhere. Lows will drop into the lower 40s in far northwest zones.
&&
Short term /6 am this morning through 6 PM Friday/...
the center of high pressure shifts offshore on Thursday setting up a
return S-SW flow. Sea breezes should have no problem developing
during the early afternoon hours. Even with a SW-S flow...surface
dewpoints will remain in the middle and upper 40s with drier air
from aloft mixing down to the surface. High temperatures in the
upper 70s to lower 80s are forecast.
Dry weather continues into Thursday night. Temperatures in the 50s
t0 lower 60s in the city are forecast which are still below normal
for this time of year...but are several degrees warmer than
Wednesday night...especially across the interior.
There is a low risk for rip currents at Atlantic Ocean beaches on
Thursday.
&&
Long term /Friday night through Wednesday/...
temperatures gradually rising to slightly above normal with slight
chances of mainly afternoon and evening showers and thunderstorms Sat through
Monday.
Global forecast models are in good general agreement through this
period showing the local area along the southern periphery of the
upper level westerlies as high pressure aloft remains south of the local
area.
A series of weak short waves will move east with the mean flow.
These weak waves will be difficult to time.
The first short wave is forecast to advect southeast toward the area Friday
aftn/eve. Because of limited moisture..decided to maintain the
existing dry forecast although a shower is possible northwest of NYC.
The second slightly stronger short wave is also forecast to advect southeast
toward the area Sat afternoon - night. With increasing low level moisture
ahead of this system...low chance probability of precipitation were continued for the region from
northwest to southeast through the day Sunday.
Additional weak waves are forecast Monday - Wednesday...bringing a chance of
mainly afternoon/evening scattered showers and thunderstorms.
Heat index values are forecast to remain below 95 degrees through
the period. Temperatures are forecast to slowly rise into the middle and upper 80s
Sunday through Wednesday. With moderate humidity...it will feel
uncomfortable.
&&
Aviation /06z Thursday through Monday/...
high pressure builds overnight and Thursday.
VFR through the taf period.
Light winds tonight. Variable in the morning...then south winds
prevail in the afternoon. Local sea breezes may result in wind
speeds around 15 kts at kjfk by middle afternoon.
Outlook for 00z 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 will be centered over the waters with winds no
greater than 5 knots. The high pressure shifts offshore on Thursday
setting up a S-SW flow. Could see a few gusts around 15 knots in the
afternoon but otherwise tranquil conditions will therefore prevail
through Friday morning.
Friday through Monday...winds and seas are forecast to remain below
Small Craft Advisory levels of 25 knots and 5 feet.
S-SW winds of 10 to 15 knots will prevail through this period with
significant wave heights ranging from 2 to 4 feet across the Atlantic
Ocean and coastal waters and 1 foot or lower elsewhere.
&&
Hydrology...
no widespread significant rainfall is forecast.
A series of weak troughs of low pressure will produce scattered showers
and thunderstorms...mainly during the afternoon and evening daily starting
Saturday. Less than 1/4 inch rain is likely with each round of
showers.
&&
Okx watches/warnings/advisories...
CT...none.
New York...none.
New Jersey...none.
Marine...none.
&&
$$
Synopsis...gc/ds
near term...ln/mps/ds
short term...ds
long term...gc
aviation...precipitable water
marine...gc/ds
hydrology...gc/ds
