Area Forecast Discussion
Issued by NWS Upton, NY

Home | 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 220537
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
137 AM EDT TUE JUL 22 2014

.SYNOPSIS...
HIGH PRESSURE REMAINS OVER THE AREA OVERNIGHT...THEN SLIDES OFFSHORE
ON TUESDAY. A COLD FRONT WILL MOVE INTO THE NORTHEAST WEDNESDAY...THEN
SLOWLY MOVE ACROSS THE AREA THROUGH THURSDAY. HIGH PRESSURE WILL FOLLOW
FROM THURSDAY NIGHT THROUGH SATURDAY. ANOTHER LOW PRESSURE SYSTEM WILL
APPROACH SUNDAY THROUGH MONDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
MINOR CHANGES WERE MADE TO HOURLY SFC TEMPS AND DEW POINT TEMPS TO
ACCOUNT FOR CURRENT OBSERVATIONS AND NEAR TERM FORECAST TRENDS.

FORECASTING THE DEVELOPMENT OF PATCHY FOG MAINLY AFT 2 AM THROUGH
SUNRISE AS TEMPS SLOWLY COOL TO THEIR DEW POINTS WHERE SFC WINDS
HAVE DECOUPLED FROM THE UPPER WIND FLOW.

OTHERWISE...RIDGING BUILDS IN WITH SUBSIDENCE MAINTAINING DRY CONDITIONS.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
THIS MORNING...SUBSIDENCE WILL MAINTAIN DRY CONDITIONS.

THIS AFTERNOON THRU EVENING...UPPER LEVEL HEIGHT FALLS AND
CONVERGENCE ALONG A SURFACE TROUGH WILL LEAD TO A SLIGHT CHANCE OF
THUNDERSTORMS ACROSS NORTHERN NJ...SOUTHEAST NY AND WESTERN CT.
ALTHOUGH SURFACE-BASED CAPE VALUES ARE FORECAST AROUND 500-1000
J/KG...DEEP LAYER FLOW AVERAGING LESS THAN 15KT WILL KEEP STORMS
SUB-SEVERE. HOWEVER...BRIEF GUSTY WINDS NEAR THUNDERSTORMS ARE
POSSIBLE GIVEN DRIER AIR/SUPER ADIABATIC LAPSE RATES BENEATH 5000
FT.

WEDNESDAY...SUMMER HEAT AND HUMIDITY RETURNS WITH DAY TIME HIGH TEMPS
REACHING THE LOWER 90S ACROSS NYC AND URBAN NORTHEAST NJ AND WITH HEAT
INDEX VALUES RISING INTO THE MID AND UPPER 90S. NO EXTENDED HEAT WAVE
IS FORECAST AS THE NEXT COLD FRONT APPROACHES. A WARM MOIST UNSTABLE
MARITIME TROPICAL AIR MASS WILL SET THE STAGE FOR THE DEVELOPMENT
OF MORE NUMEROUS SHOWERS AND TSTMS BY WED AFTN MAINLY WEST AND
NORTH OF NYC.

THERE IS A MODERATE RISK OF RIP CURRENTS ON TUESDAY...PARTICULARLY TUESDAY
AFTERNOON WITH ENHANCED SEA BREEZE DEVELOPMENT.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
ATTENTION MID WEEK WILL BE FOCUSED ON THE PROGRESSION OF A SLOW
MOVING COLD FRONT ACROSS THE NORTHEAST. GENERALLY DECENT MODEL
AGREEMENT BETWEEN THE 12Z MODEL SUITE...MINUS THE ECMWF...ON THE
TIMING OF THE FRONT REACHING THE AREA OVERNIGHT WED. THE FRONT THEN
LOOKS TO STALL JUST OFFSHORE...WITH A SFC LOW THEN FORMING AND
RIDING THE FRONT THURS...BRINGING ANOTHER CHC OF PCPN DURING THE DAY
THURS...EVENTUALLY TAPERING OFF THURS NIGHT AS HIGH PRESSURE BUILDS
IN BEHIND THE FRONT.

BEGINNING WED DURING THE DAY...SFC LOW TREKKING THROUGH SOUTHERN
CANADA WILL DRAG THE ASSOCIATED COLD FRONT THROUGH THE GREAT
LAKES...EVENTUALLY HAVING THE FRONT NEAR SOUTHERN NEW ENGLAND BY 00Z
THURS. STRONG WAA OUT AHEAD OF THE FRONT WILL LOOK TO INJECT IN A
VERY WARM...MOIST ATMOSPHERE. MULTIPLE WEAK VORT MAXES WILL MOVE THROUGH
THE NORTHEAST THROUGHOUT THE DAY OUT AHEAD OF THE MAIN UPPER LVL
TROUGH...WHICH COMBINING WITH DECENT INSTABILITY AND MARGINAL SHEAR
COULD PRODUCE AN ISO TSTM OVER AREAS WELL NORTH AND WEST OF NYC
METRO. WHILE THE SVR THREAT LOOKS TO REMAIN NORTH OF THE
AREA...CANNOT RULE OUT A STRONGER STORM OVER LOWER HUDSON AND
INTERIOR SW CT AREAS. THE MAIN PCPN EVENT FOR THE AREA WILL THEN BE
AS THE COLD FRONT SWINGS THROUGH WED NIGHT. EXPECTING THE THREAT FOR
THUNDER TO DIMINISH OVERNIGHT WITH LOSS OF INSTABILITY/HEATING...SO
THINKING THE THREAT WILL TURN MORE TO HEAVY RAIN AND POTENTIAL FOR
FLOODING WITH PWATS HITTING AROUND 2 INCHES. POSSIBLE BREAK IN THE
PCPN EARLY THURS...THEN ANOTHER ROUND DURING THE DAY AS THE
AFOREMENTIONED SFC LOW FORMS ALONG THE FRONT AND PUSHES TO THE
NORTHEAST AND EAST. MINIMAL INSTABILITY THURS WILL KEEP A LOWER CHC
THREAT FOR TSTMS...MAINLY OVER LI AND TO THE SOUTH. WILL MAINTAIN
CHC POPS FOR NOW WITH UNCERTAINTY ON THE EXACT TIMING OF THE PCPN.

PCPN TAPERS OFF THURS NIGHT AS FRONT EXITS THE REGION AND SFC HIGH
BUILDS IN FROM THE WEST. MUCH COOLER AND DRIER AIR MASS MOVES IN BEHIND
THE FRONT FOR FRI AS THE REGION SITS BETWEEN THE DEPARTING UPPER LVL
TROUGH AND RIDGING OVER THE CENTRAL US...RESULTING IN DRY AND MOSTLY
SUNNY SKIES. EXPECT THE DRY WX TO CONTINUE THROUGH SAT.

SOME MODEL DISCREPANCY THEN SUNDAY INTO THE BEGINNING OF NEXT WEEK
WITH THE HANDLING OF THE NEXT LOW PRESSURE SYSTEM. 00Z ECMWF WAS THE
MORE PROGRESSIVE OF THE SOLUTIONS PUSHING THE LOW THROUGH SUN NIGHT
INTO MON. HOWEVER... THE 12Z MODEL SUITES A BIT SLOWER IN HOLDING
THE LOW BACK OVER THE GREAT LAKES. WITH THE UNCERTAINTY...MAINTAINED
THE PREVIOUS THINKING OF CHC POPS FOR THE PERIOD FOR NOW UNTIL THE
MODELS COME INTO BETTER AGREEMENT.

AS MENTIONED...STRONG SURGE OF WARM AIR WED WILL PUSH TEMPS WELL
ABOVE NORMAL...WITH SOME SPOTS OF NYC METRO POTENTIALLY EVEN HITTING
90. THE ONSHORE FLOW WILL ALLOW FOR IMMEDIATE COASTAL AREAS TO
HOVER IN LOWER-MID 80S. TEMPS WILL THEN DROP THURS AND FRI TO A
FEW DEGREES BELOW NORMAL...EVENTUALLY REBOUNDING TO NORMAL LEVELS
FOR THE WEEKEND.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
HIGH PRESSURE SLOWLY MOVES OFFSHORE ON TUESDAY.

PRIMARILY VFR WITH LIGHT SW FLOW OVERNIGHT. BRIEF MVFR POSSIBLE AT
KSWF/KHPN/KISP/KGON AROUND 09-11Z...BUT LOW CONFIDENCE IN THIS
HAPPENING.

SEA BREEZE TIMING COULD BE OFF +/- 2 HOURS ON TUESDAY. INCREASING
CONFIDENCE IT MAKES IT TO KEWR...RESULTING IN WIND DIR AROUND
170-180 TRUE BY LATE AFTERNOON.

.OUTLOOK FOR 06Z WED THROUGH SAT...
.TUE NIGHT-WED...PRIMARILY VFR. ISOLATED SHRA/TSTM NW OF THE NY METRO
LATE.
.WED NIGHT-THU...SLOW MOVING COLD FROPA. BRIEF MVFR OR LOWER CONDS
IN SCT-NUMEROUS SHOWERS/TSTMS.
.THU NIGHT-SAT...VFR.

&&

.MARINE...
A RELAXED PRESSURE GRADIENT WILL KEEP WINDS TO 15 KT OR LESS AND
SEAS 4 FT OR LESS ON THE OCEAN WATERS AND 1 FT OR LESS ON THE
REMAINDER OF THE WATERS AROUND LONG ISLAND THROUGH TUESDAY. THE
EXCEPTION WILL BE POTENTIAL FOR COASTAL JET AND A BRIEF PERIOD OF
15 TO 20 KT WINDS ACROSS THE WESTERN OCEAN WATERS AND ADJACENT
NEAR SHORE WATERS LATE TUE AFT/EVE.

TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...WINDS AND SEAS WILL INCREASE
APPROACHING SMALL CRAFT ADVISORY LEVELS OF 25 KT AND 5 FT SEAS WED
AFTERNOON AND NIGHT.

STRONG SW FLOW WED-WED NIGHT AHEAD OF THE COLD FRONT COULD SEE
OCNL GUSTS UP TO 25 KTS...AND SHOULD SEE SEAS AROUND 5 FT ON THE
OCEAN WATERS. ONCE THE FRONT PASSES THURS...HIGH PRESSURE BUILDS
IN...ALLOWING FOR SUB-SCA CONDITIONS TO FORM ACROSS ALL WATERS BY
THURS NIGHT. SUB-SCA CONDITIONS THEN LAST THROUGH THE COMING
WEEKEND.

&&

.HYDROLOGY...
DRY INTO TUESDAY MORNING...THEN ISOLD CONVECTION COULD BRING
LOCALIZED AMOUNTS UP TO A FEW TENTHS OF AN INCH TUESDAY
AFTERNOON/EVENING MAINLY TO AREAS N/W OF NYC.

LATE WED THROUGH THU WILL BE THE NEXT CHC OF A SIGNIFICANT RAINFALL
WITH THE POTENTIAL FOR 1/4 TO 1/2 INCH WITH THE APPROACH OF A SLOW
MOVING COLD FRONT. A FEW HEAVY SHOWERS AND TSTMS COULD PRODUCE BRIEF
HEAVY DOWNPOURS WITH ISOLATED AMOUNTS OF UP TO AROUND 1 INCH.

&&

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

&&

$$
SYNOPSIS...MMD/SEARS
NEAR TERM...GC
SHORT TERM...MMD
LONG TERM...SEARS
AVIATION...PICCA
MARINE...GC/MALOIT
HYDROLOGY...GC/MALOIT







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