Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service New York New York
157 am EDT Monday Jul 25 2016

Synopsis...
high pressure moves offshore tonight. A cold front approaches on
Monday and moves through the region Monday night. High pressure
builds to the west Tuesday and moves off the southeast coast
Wednesday into Thursday. A series of low pressure waves move
across the region from Thursday afternoon through Sunday.

&&

Near term /until 6 am this morning/...
slight adjustments were made to temperatures, dewpoints, and
cloud coverage to better match observed trends. While convection
in Pennsylvania has decreased, a lot of model guidance reinitiates
some convection and has some quantitative precipitation forecast moving into the western parts of
the region going into early Monday.

12z model suite shows weak shortwave quickly moving east tonight,
with embedded vorticity maxima tracking toward the area overnight
and toward morning.

Expect partly cloudy to mostly clear skies this evening giving
way to increasing clouds overnight.

Humidity levels begin to increase as a warm front to the west
jumps north. An area of showers and thunderstorms will approach
western sections toward morning ahead of the aforementioned
shortwave.

Very warm temperatures are expected tonight, with lows ranging
from the upper 70s in and around NYC, to the upper 60s across the
interior.

&&

Short term /6 am this morning through 6 PM Tuesday/...
initial shortwave/vort moves across or just south of the area in
the morning per latest model suite.

It appears that scattered showers and thunderstorms will
accompany this feature, with better chance near the coast and
south.

Then, upstream trough approaches, along with sfc cold front. With
increasing low level moisture, deep mixing and increasing surface
based instability, numerous thunderstorms should approach and
impact a good portion of the area late in the day. Moderate cape,
and increasing shear will result in a few stronger to possibly
severe thunderstorms, with the biggest threat gusty winds.

With the cloud cover expected, it appears that temperatures may be
a degree or lower than previously thought. Much depends on amount
of sunshine that is realized as h8 temps increase to 18-20c. Went
above MOS numbers, and with dew points rising into the 70s, expect
heat indices well in the 90s, and exceeding 100 in a few spots.

The excessive heat watch for NYC and New Jersey Metro has been converted
to a heat advisory, and the heat advisory remains in effect for
the remainder of the area. The only exception is eastern Long
Island and southeast CT where temperatures remain in the 80s due to
clouds and south winds. As such, heat advisory has been cancelled
for those locations.

Any evening showers and thunderstorms move east and weaken in
time.

Another warm night is in store Monday night as the front slowly
approaches and moves through.

&&

Long term /Tuesday night through Sunday/...
mainly zonal flow will continue across the northern tier and along
the US/Canadian border as a high pressure ridge remains over the
southern states and low pressure remains over eastern Canada Tuesday
into 12z Thursday. Heat and humidity will persist through Thursday.

Shortwave energy is forecast to come ashore of the Pacific northwest
late Tuesday and begin to dig an trough into the upper plains
Wednesday. This shortwave is expected to reach the East Coast
Thursday afternoon. An eastern trough then remains into next weekend
as an up stream ridge builds over the northern rockies and into the
southwest. A series of shortwaves rotate through the eastern trough
through from Thursday through next weekend. Timing and placement of
the waves is uncertain at this time. However, unsettled weather is
expected with mainly diurnally driven convection each day. With the
uncertainty will have slight chance and chance pops Thursday
through Sunday, with higher pops inland and during each afternoon
and evening.

With the longwave trough digging into the eastern states the core of
the hot air will be shifted to the south by Friday, with
temperatures likely returning to more normal levels.

&&

Aviation /06z Monday through Friday/...
a warm front lifts through the terminals during the pre-dawn
hours as high pressure slides offshore. A cold front approaches
this afternoon and passes through the region this evening. High
pressure returns tonight.

Primarily a VFR forecast for most terminals. Some convection
associated with an approaching warm front developing over southeast PA
and west New Jersey will lift towards the region and could impact western
terminals by 09-10z. That wave of convection should pass through
the terminals by 13-15z. Brief MVFR conditions possible.

MVFR vsbys possible in haze for knyc terminals from late morning
through early afternoon. VFR otherwise.

Cold front approaches this afternoon. Convection will fire up west
of the region and looks to impact western terminals from around
20z-02z.

SW flow less than 10 knots will give way to afternoon sea breezes at
coastal terminals 10-15 knots.

Gusty winds and heavy rain possible in convection.

VFR conditions expected tonight, but it is possible that outlying
terminals, such as khpn and kgon could have MVFR or lower vsbys in
fog late tonight.

Outlook for 06z Tuesday through Friday...
tonight...shra/tsra taper off from west to east. MVFR visibility
possible north and east of knyc in fog.
Tuesday-Wednesday night...VFR.
Thursday-Thursday night...mainly VFR, except MVFR or lower
possible in isolated to scattered showers and thunderstorms,
mainly late in the day and at night.
Friday...chance of MVFR or lower in scattered showers and
thunderstorms.

&&

Marine...
winds and seas forecast remain on track, with no changes at this
time.

High pressure moves offshore tonight. A cold front approaches the
waters Monday and moves through Monday night.

Sub Small Craft Advisory conditions are anticipated through Monday night.

High pressure builds to the west of the forecast waters Tuesday and
moves off the southeast coast Wednesday and Thursday. A series of
weak low pressure waves will moves across the forecast waters
Thursday afternoon through next weekend with scattered showers and
thunderstorms possible.

From Tuesday through Friday winds and seas are expected to remain
below advisory levels across the forecast waters.

&&

Hydrology...
there is the potential for 1/4 to 1/2 inch of rainfall, with
locally higher amounts, possibly 1 inch or more, in showers and
thunderstorms Monday and Monday night.

Dry weather returns for Tuesday and Wednesday. There is the
potential for scattered showers and thunderstorms, mainly across the
interior, during the afternoons and evenings Thursday through next
weekend.

&&

Okx watches/warnings/advisories...
CT...heat advisory from noon today to 8 PM EDT this evening for
ctz005>010.
New York...heat advisory from noon today to 8 PM EDT this evening for
nyz067>075-078-080-176>179.
New Jersey...heat advisory from noon today to 8 PM EDT this evening for
njz002-004-006-103>108.
Marine...none.

&&

$$
Synopsis...met/pw
near term...jm/met/pw
short term...precipitable water
long term...met
aviation...mps
marine...jm/met/pw
hydrology...met/pw

National Weather Service Glossary of Abbreviations