Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 170238
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1038 PM EDT TUE SEP 16 2014

.SYNOPSIS...
HIGH PRESSURE BUILDS IN FROM THE WEST AND GETS REINFORCED
WEDNESDAY NIGHT AND THURSDAY...STAYING ACROSS THE REGION THROUGH
FRIDAY NIGHT. HIGH PRESSURE MOVES OFFSHORE FOR THE WEEKEND WITH A
COLD FRONT APPROACHING THE BEGINNING OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
HIGH PRESSURE AT THE SURFACE STARTS TO BUILD IN FROM THE WEST
TONIGHT...GIVING THE REGION MORE OF A NORTHERLY FLOW. THIS WILL
ADVECT IN COOLER...DRIER AIR. IN ADDITION...THE CLOUDS WILL
CONTINUE TO DECREASE AND WINDS WILL BE RATHER LIGHT...SO
RADIATIONAL COOLING WILL BE SOMEWHAT EFFICIENT AS WELL.
THEREFORE...PREFERRED LOWER MAV GUIDANCE COMPARED TO MET GUIDANCE
FOR LOWS...WHICH ARE FORECAST TO RANGE FROM THE LOWER 40S TO UPPER
50S...LOWEST FOR RURAL INTERIOR SECTIONS AND HIGHEST NEAR NYC.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
OVERALL...SUBTROPICAL JET WILL STILL BE SOUTH OF THE AREA. THE
OVERALL TROUGH IN THE MID TO UPPER LEVEL WILL BECOME ONE OF
DECREASED WAVELENGTH...INDICATING A SHARPENING OF THE TROUGH AND
THIS WILL HELP USHER IN A STRONGER HIGH PRESSURE AREA BY WEDNESDAY
NIGHT FROM SOUTH CENTRAL CANADA.

ONE SURFACE HIGH PRESSURE WEAKENS AS IT CENTERS OVER THE REGION
WEDNESDAY. THE FLOW ALOFT WILL BECOME LIGHTER WITH THE
GEOPOTENTIAL HEIGHT GRADIENT DECREASE AND SURFACE PRESSURE
GRADIENT DECREASING AS WELL. LIGHT WINDS AT THE SURFACE SHOULD
EASILY GIVE WAY TO SEA BREEZE CIRCULATIONS AS LAND TEMPERATURES
EXCEED SEA SURFACE TEMPERATURES. NOT EXPECTING SUBSIDENCE TO BE
THAT STRONG...SO THINKING THAT SOME DIURNAL CU WILL DEVELOP AGAIN
LATER IN THE AFTERNOON. MAX TEMPS WERE A BLEND OF NAM12 AND
GMOS...WITH SLIGHTLY COOLER READING ALONG THE COAST BUT OVERALL
MOSTLY LOWER 70S.

DRY CONDITIONS WITH CLEARING SKIES EXPECTED AGAIN WEDNESDAY NIGHT
AS A STRONGER CANADIAN HIGH PRESSURE AREA STARTS TO BUILD SOUTHEAST
CLOSER TO OUR REGION. THIS WILL ESSENTIALLY REINFORCE HIGH
PRESSURE ACROSS THE LOCAL REGION. USED A BLEND OF 3/4 MET AND 1/4
MAV GUIDANCE FOR LOWS. AGAIN EXPECTING COLD AIR ADVECTION AND
RADIATIONAL COOLING TO CONTRIBUTE.

THERE IS A MODERATE RISK OF RIP CURRENT DEVELOPMENT AT THE
ATLANTIC BEACHES ON WED. THIS MAY INCREASE TO A HIGH RISK LATE IN
THE DAY DUE TO SWELLS FROM TROPICAL CYCLONE EDOUARD...SITUATED
WELL OUT TO SEA.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
GENERALLY DECENT AGREEMENT AMONG THE 12Z MODEL SUITE WITH SYNOPTIC
FEATURES HEADING INTO THIS WEEKEND...WITH DIVERGING SOLUTIONS ON THE
HANDLING OF THE APPROACHING COLD FRONT. WEAK SFC LOW TREKS THROUGH
SOUTHERN CANADA EARLY THURS...WITH ASSOCIATED COLD FRONT TRAILING
ACROSS NEW ENGLAND. BUILDING SURFACE HIGH TRAVERSES THE REGION FROM
THE GREAT LAKES REGION THROUGH THE NORTHEAST THURS INTO THE COMING
WEEKEND. ALOFT...MID LEVEL TROUGH SWINGS THROUGH THURS/FRI...WITH
ZONAL FLOW TAKING HOLD THROUGH THE REMAINDER OF THE WEEKEND.
MULTIPLE WEAK SHORTWAVES EMBEDDED WITH THE FLOW ALOFT WILL PUSH
THROUGH DURING THIS TIME...BUT OVERALL WEAK DYNAMICS COMBINED WITH
MINIMAL MOISTURE SHOULD RESULT IN A PREDOMINATELY DRY FORECAST. NAM
AND GFS HINT AT AFTN DEVELOPMENT THURS CORRESPONDING WITH THE
PASSAGE OF THE STRONGEST WAVE...BUT CONFIDENCE IS TOO LOW TO INCLUDE
POP MENTION AT THIS TIME. SUBSIDENCE BUILDING IN ALOFT SHOULD AID IN
KEEPING MOSTLY SUNNY CONDITIONS FRIDAY.

FOR THE WEEKEND...ZONAL FLOW BEGINS TO WEAKEN BY SAT WITH THE NEXT
TROUGH DIPPING SOUTH ACROSS THE NORTH PLAINS. SURFACE HIGH PUSHES
OFFSHORE AS THE LOW PRESSURE SYSTEM LIFTS INTO THE GREAT LAKES
REGION...PLACING THE NORTHEAST INTO THE WARM SECTOR BY SUNDAY.
TIMING AND STRENGTH DIFFERENCES...WITH THE 12Z GFS SOLUTION A MORE
POTENT SOLUTION SUN/MON...THEN ALIGNING ONCE AGAIN WITH THE ECMWF BY
TUES. CMC LOOKS TO DEEPEN TOO MUCH/TOO QUICKLY SO SIDED MORE TO A
COMPROMISE OF THE GFS/ECMWF FOR NOW. AS SUCH...SWING THE COLD FRONT
THROUGH SOMETIME MONDAY-MONDAY NIGHT WITH HIGH PRESSURE BUILDING IN
BY TUESDAY. CHC POPS IN FOR MONDAY WITH STILL UNCERTAINTY ON WHEN
EXACTLY THE PCPN WILL OCCUR...THOUGH ANTICIPATING IT RIDING THE
FRONTAL PASSAGE...WITH THINGS QUICKLY DRYING IN THE WAKE WITH THE
HIGH.

THURSDAY TEMPS REMAIN NEAR NORMAL. FRIDAY TEMPS BELOW NORMAL WITH A
SHOT OF CAA AS THE HIGH BUILDS INTO THE REGION. ALONG WITH THE
DIPPING TEMPS...SHOULD SEE DEW PTS DROPPING...WITH SOME INTERIOR
REGIONS EVEN DROPPING INTO THE 30S. AT THE MOMENT...FROST
DEVELOPMENT LOOKS TO REMAIN NORTH OF THE FORECAST AREA...BUT WILL BE
WATCHFUL. TEMPS REBOUND QUICKLY BACK TO NORMAL FOR THE
WEEKEND...WITH RISING HEIGHTS ALOFT AND DECENT WAA RIDING THE
SOUTHERLY WINDS AS THE HIGH PUSHES OFFSHORE.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
HIGH PRES BUILDS INTO THE REGION.

VFR THROUGH THE TAF PERIOD.

N/NW WINDS AT 5 KT OR LESS THROUGH WEDNESDAY MORNING. WINDS WILL
BE LIGHT ENOUGH TO CARRY VRB IN THE TAF. NORTH WINDS INCREASE TO
5-7 KT AFTER 12-14Z. SEA BREEZES WILL SHIFT WINDS TO THE SOUTH IN
THE AFTERNOON.

.OUTLOOK FOR 00Z THURSDAY THROUGH SUNDAY...
.THURSDAY-SUNDAY...VFR.

&&

.MARINE...
A CONTINUANCE OF SUB SCA CONDITIONS ARE EXPECTED WITH A WEAK
PRESSURE GRADIENT IN PLACE. HOWEVER...SWELLS FROM EDOUARD WILL
BUILD OCEAN SEAS THROUGH WEDNESDAY NIGHT. LEANED CLOSER TO THE
NORTH ATLANTIC HURRICANE MODEL GUIDANCE AND NOT WAVEWATCH...SO
NOT GOING WITH SCA AT THIS TIME AND LIMITED OCEAN SEAS TO 4 FT.

SUB-SCA CONDITIONS THURSDAY WITH WEAK OFFSHORE FLOW AND ANY SWELLS
FROM EDOUARD DECREASING. INCREASING NE FLOW FRIDAY SHOULD AID IN
PUSHING SEAS TO 5-6 FT ON THE OCEAN INTO THE WEEKEND. OCNL GUSTS TO
25 KT PSBL AS WELL DURING THIS TIME ON THE OCEAN. CONDITIONS
DIMINISH BACK DOWN TO SUB-SCA EVERYWHERE BY SAT AND REMAIN AS SUCH
HEADING INTO NEXT WEEK.

&&

.HYDROLOGY...
NO SIGNIFICANT PRECIPITATION RESULTING IN HYDROLOGIC ISSUES IS
EXPECTED THROUGH THIS WEEKEND.

&&

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

&&

$$
SYNOPSIS...JM/SEARS
NEAR TERM...JM/DW
SHORT TERM...JM/DW
LONG TERM...SEARS
AVIATION...MPS
MARINE...JM/SEARS
HYDROLOGY...JM/SEARS








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