Area Forecast Discussion
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FXUS61 KOKX 232346
Area Forecast Discussion
National Weather Service New York NY
746 PM EDT Sun Apr 23 2017
High pressure moves offshore tonight into Monday. A wave of low
pressure over the southeastern states moves to the southeast
coast Monday, then tracks up along the eastern seaboard through
midweek. High pressure will build back in for the end of the
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Forecast is on track. Minor adjustments to T/Td/Sky and winds
based on latest obs and trends.
Region will lie in a near zonal upper flow between a polar
upper low over interior Quebec and a closed upper low moving
trough the deep south. At the surface...high pressure pushes
east of the region tonight.
Tranquil conditions tonight...with increasing high and mid-deck
overnight ahead of of a slowly approaching low pressure system from
the south. Lows nears seasonable...upper 30s across far outlying
areas and 40s elsewhere.
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Models in fairly good agreement with a closed upper low over the
deep south Monday...slowly sliding to the southeastern US coast
Monday Night. In response...a broad southern low should develop into
a coastal low pressure along the Southeastern US coast Monday
Locally...weak ridging surface/aloft on Monday appears to give way
to approaching lead short wave energy ahead of the upper low...with
surface high pressure gradually sliding offshore. Timing and
strength of the approaching shortwave energy and of associated theta-
e advection range from late Monday afternoon into Monday
night...which is resulting in timing spread of onset of rain
development into the region. Latest trend is slower onset of rain
late Monday into Monday night...with increasing likelihood of rain
from south to north late Monday Night. In addition e/ne winds will
be increasing along the coast Monday Night...with gusts 25 to 30 mph
possible by daybreak Tuesday.
Despite warmer temps aloft than today...increasing high and mid
cloud cover and easterly flow will likely keep temps near seasonable
levels on Monday. Generally mid to upper 50s south and east
coasts...lower/mid 60s NYC/NJ...and upper 60s far interior. Near
seasonable temps Monday night.
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Models have come into better agreement with the track of the
low up the east coast Tue/Wed....with the GEM and NAM both
shifting eastward as compared to 24 hours ago. NWP is in good
agreement through the end of the week...but then differences are
apparent for next weekend leading to a low confidence forecast.
Low pres over NC Tue morning will track to the Mid Atlantic
coast Tue night while weakening. A tight pres gradient will
remain across the area due to departing high pres to the north
producing gusty easterly winds. 40-50 kt LLJ lifts through late Tue
aftn/eve...but a low level inversion should keep most of these
Rain becomes widespread Tue morning with strengthening
overrunning pattern. Timing of heaviest rainfall will coincide
with the LLJ late Tue aftn/eve and location is pointing towards
the eastern Long Island/CT. See hydro section for rainfall
amounts and potential impacts. Winds abate on Wed as the low
approaches and passes just S of Montauk Wed night. Noting mid
level drying from west to east on Wed...have transitioned to
light rain/drizzle. Sfc Low is slow to depart and continues to
weaken Wed night/Thu before being absorbed back into the
Meanwhile...a broad upper trough will be developing over the
rest of the CONUS with a shortwave tracking through the Great
Lakes on Thu. Downstream ridging will limit the eastward
progression of this system with a sfc cold front moving into the
area Thu night and stalling nearby with potentially unsettled
weather through the weekend.
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
VFR overnight and Monday as high pressure builds over the
northeast and moves offshore. Clouds will lower late in the day
Monday, but should remain 5 KFt or higher.
S/SE winds diminish tonight and become light and variable
outside of city terminals. E/SE winds prevail Monday, around 10
kts. A few coastal locales may see a few afternoon gusts to 15
to 20 kt.
.OUTLOOK FOR 00z TUESDAY THROUGH FRIDAY...
.Monday night...VFR in the evening, then chance MVFR later at
.Tuesday...IFR/LIFR in rain. NE gusts 20-25 KT near coast
possible during the day.
.Wednesday...MVFR, possibly improving to VFR later in the day.
With high pressure influencing the waters tonight into Monday
morning tranquil conditions are expected on the waters.
A low pressure system will slowly move up the southeastern coast
Monday into Monday Night...allowing for a tightening e/ne gradient
over the waters late Monday into Monday night. A return to SCA
conditions are expected on the ocean waters Monday night...and
likely across the nearshore waters later Monday night.
SCA conds will likely continue on the waters into Wed morning
for both winds and seas. Gusts then diminish...although seas
will remain elevated through Fri due to swells from the
weakening storm system. There is a low potential for gale force
winds...mainly on the ocean waters Tue/Tue eve.
Between 3/4 and 2 inches of rainfall is possible late Monday
into Wednesday. Highest amounts are expected across eastern Long
Minor flooding of low lying and poor drainage is possible.
Potential for minor coastal flooding for vulnerable coastal
communities...mainly along the southern bays of Western LI and
Western LI Sound...with the Tue eve high tide cycle. This is in
response to a low pressure system moving northward along the
eastern seaboard. Only 1/2 to 1 ft of surge is needed to reach
minor flood thresholds Tue evening.
MARINE...Small Craft Advisory from 2 AM to 8 PM EDT Tuesday for ANZ330-
Small Craft Advisory from 6 PM Monday to 8 PM EDT Tuesday for