Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KOKX 180259
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1059 PM EDT Mon Jul 17 2017

.SYNOPSIS...
A weak trough remains nearly stationary over the region through
Thursday. A cold front passes Friday, followed briefly by high
pressure Saturday. A warm front approaches Sunday, and low
pressure impacts the area early next week.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Convection has dissipated across the region. However, both the
upper and surface troughs move into the area overnight. Some of
the high res models, in particular the 3km NAM, fires up
convection across the Lower Hudson Valley and southern CT. The
HRRR on the other hand is quiet, but has also done poorly with
over forecasting convection over NE PA. Have decided to keep
low chances overnight with moderate to high instability in
place.

The other forecast challenge will be any fog/stratus
development overnight. Typically, in the warm season, dense fog
is not a problem. The greatest chance for fog development will
be across eastern CT and far eastern Long Island, with patchy
fog possible everywhere outside of the city.

Low temperatures will be several degrees above normal.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Although the short wave will move east of the area by Tuesday, a
secondary upper low to the southwest and the stalled frontal
boundary will likely provide focus for at least isolated showers
and thunderstorms through Tuesday night, with the greatest
potential north and west of the city. High temperatures will be
close to normal, while lows will once again be near to slightly
above climatological normals with humid conditions lingering.
The potential for fog to redevelop will need to be monitored.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Unsettled weather expected through much of this time frame.

Lingering weak trough aloft, along with sfc trough should result in
a few showers or thunderstorms Wednesday.

Thereafter, the weak upper trough just to our south makes slow
progress east Wednesday night and Thursday, with gradually lowering
heights over the northeast late in the week and through the weekend
as larger upstream trough tracks east. A surface cold front ahead of
these lowering heights slowly moves through Friday.

Cannot rule out an isolated shower or thunderstorm during this time
frame, although drier air in NW flow Friday should result in
predominately dry conditions.

Thereafter, the weekend forecast remains in question due to
differences in handling potential MCS riding along a warm front. At
this time, feel Saturday remains dry, although latest ECMWF and
Canadian solutions suggest otherwise. Hard to pinpoint these
complexes this far out, and will maintain higher probabilities for
the latter portion of the weekend as the main low, and front
approach.

Unsettled weather continues into Monday as a cold front slowly
pushes through.

Temperatures Wednesday and Thursday look warm, with above normal
readings anticipated. By the weekend, the lowering heights should
result in closer to normal temps. Potential showers/tstms will also
impact temps if they do indeed occur this weekend across the area.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
A weak front remains nearly stationary over the region through
Thursday.

VFR through the period at the city terminals. However, there is
a possibility that fog does develop overnight, bringing vsby
down to MVFR conditions. Confidence is not high enough to
mention in the TAFS.

Outside of the city, expecting MVFR ceilings and visibilities to
develop from east to west, beginning around 06Z. The lowest
conditions are expected to be at KGON overnight, where IFR cigs
and visibilities are possible. VFR conditions then return
Tuesday morning as any fog and/or low clouds lift.

Southerly flow will become light and variable outside of the
city overnight. Winds then return out of the south Tuesday
afternoon at 10 kt or less.

.OUTLOOK FOR 00Z TUESDAY THROUGH SATURDAY...
.Tuesday-Thursday...Chance of showers and thunderstorms,
primarily in the late afternoon and from NYC north and west.
.Friday-Saturday...VFR.

&&

.MARINE...
A very weak pressure gradient over the region will limit winds
to 10 kt or less, and keep seas well below SCA levels through
Saturday.

Any thunderstorms that move across the area waters may produce
brief SCA to possibly gale conditions.

&&

.HYDROLOGY...
There is a low chance for heavy rain/flooding this weekend
ahead of a frontal system.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$

SYNOPSIS...MD/PW
NEAR TERM...MD/DW
SHORT TERM...MD
LONG TERM...PW
AVIATION...CB
MARINE...MD/PW
HYDROLOGY...MD/PW



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.