Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 310816
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
416 AM EDT SUN AUG 31 2014

.SYNOPSIS...
LOW PRESSURE TRACKING ACROSS EASTERN CANADA WILL SEND A TROUGH
ACROSS THE AREA LATE THIS AFTERNOON INTO THIS EVENING. ANOTHER
TROUGH WILL THEN WORK ACROSS THE AREA MONDAY AFTERNOON AND
EVENING. WEAK HIGH PRESSURE BRIEFLY BUILDS IN MONDAY NIGHT INTO
TUESDAY MORNING. A COLD FRONT WILL THEN MOVE THROUGH TUESDAY
NIGHT WITH HIGH PRESSURE BUILDING IN FROM THE SOUTH AND WEST
THROUGH THURSDAY. THE HIGH MOVES OFFSHORE FRIDAY WITH ANOTHER COLD
FRONT APPROACHING INTO THE BEGINNING OF NEXT WEEKEND.

&&

.NEAR TERM /THROUGH 6 AM MONDAY/...
A SIGNIFICANT CHANGE IN THE WEATHER THE LAST 24H AS THE UPPER
RIDGE AXIS HAS PASSED TO THE EAST WITH AN INFLUX OF TROPICAL
MOISTURE FROM THE GULF COAST STATES. LATEST WATER VAPOR IMAGERY
SHOWS THE MOISTURE TRANSPORT FROM THE WESTERN GULF OF MEXICO WITH
MULTIPLE SHORT WAVES EMBEDDED IN THE FLOW. THESE LATER TODAY WILL
INTERACT WITH A SFC TROF TO PRODUCE WIDESPREAD CONVECTION ACROSS THE
NORTHERN MID ATLANTIC AND SOUTHERN NEW ENGLAND STATES. LATEST DAY
1 CONVECTIVE OUTLOOK FROM SPC HAS ALSO INTRODUCED A SLIGHT RISK OF
SEVERE WEATHER ACROSS THE NY METRO AREA...FROM NYC AND POINTS
NORTH AND WEST WHERE THE GREATEST INSTABILITY AND WIND SHEAR WILL
RESIDE.

HOWEVER...THE PRIMARY THREAT LOOKS TO BE LOCALIZED HEAVY RAINFALL
LATE THIS AFTERNOON TO THE WEST OF NYC...THEN OVERSPREADING THE
REST OF THE TRI-STATE AREA THIS EVENING. PWS IN EXCESS OF 2
INCHES...MLCAPES OF 1000-1500 J/KG...AND 30-40 KT OF DEEP-LAYERED
SHEAR SUPPORTS ORGANIZED CONVECTION WITH POSSIBLE LINE SEGMENTS
AND STRONG/DAMAGING WINDS. THERE IS STILL SOME CONCERN FOR THE
BOUNDARY TO LAY DOWN OR BECOME NEARLY STATIONARY EAST OF
NYC...WITH THE POSSIBILITY OF TRAINING OF CELLS. THE 00Z MODEL
GUIDANCE HAS SHOW MORE PROGRESSION THAN 24H AGO.

IN ADDITION...VERY WARM...MUGGY CONDITIONS WILL PREVAIL WITH HIGHS
IN THE LOW TO MID 80S AND DEW POINTS AROUND 70. PREFERRED THE
COOLER MAV GUIDANCE DUE TO THE EXPECTED CLOUD COVER TODAY.
HOWEVER...SHOULD THERE BE SOME BREAKS THIS AFTERNOON...A FEW
DEGREES CAN EASILY BE ADDED TO THESE HIGHS.

OVERNIGHT LOWS WILL HAVE A TOUGH TIME GETTING TOO FAR BELOW THE 70
DEGREE MARK WITH CLOUD COVER AND AN ONSHORE FLOW.

&&

.SHORT TERM /6 AM MONDAY THROUGH 6 PM MONDAY/...
POTENTIAL EXISTS FOR ANOTHER ROUND OF STRONG AFT/EVE CONVECTION
ON MON AS ANOTHER TROF SETS UP JUST WEST OF THE AREA AND THEN
APPROACHES BY EARLY EVE. THIS TIME AROUND THOUGH WINDS ALOFT ARE
NOT AS FAVORABLE FOR ORGANIZED CONVECTION. HOWEVER...MLCAPES OF
1000-1500 J/KG COUPLED WITH PWS AROUND 2 INCHES WILL KEEP
LOCALIZED HEAVY RAINFALL A THREAT.

HIGHS MON ARE FORECAST TO BE A TOUCH WARMER WITH DEW POINTS
REMAINING AROUND 70.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
THE DOMINANT PATTERN IN THE LONG TERM IS THAT OF RIDGING ON AVERAGE.
ON A LARGE SCALE...AN UPPER LEVEL RIDGE IS APPARENT ON THE MODEL
HEIGHT FIELDS ALOFT FROM QUEBEC TO THE MID-ATLANTIC. A RELATIVELY
STRONGER UPPER LEVEL TROUGH PASSES NORTH OF THE REGION LATE
TUESDAY INTO EARLY WEDNESDAY WITH SOME MORE HEIGHT FALLS AND A
TRANSITION TO ZONAL FLOW. RIDGING RESUMES THEREAFTER WITH THE
LARGE RIDGE ACROSS THE SOUTHERN U.S. PUSHING NORTH FROM WEDNESDAY
THROUGH FRIDAY.

AT THE SURFACE...A SURFACE TROUGH MOVING IN FROM THE WEST
DISSIPATES WITHIN THE REGION WITHOUT MUCH UPPER LEVEL SUPPORT ON
MONDAY. A WEAK PRESSURE GRADIENT IS LEFT IN ITS PLACE WITHOUT A
STRONG PRESENCE OF HIGH PRESSURE. THE JET STREAM WILL BE LIFTING
NORTH AWAY FROM THE REGION HELPING EXPLAIN THE LACK OF SUPPORT
ALOFT. THE JET PUSHES BACK SOUTH TUESDAY NIGHT INTO EARLY
WEDNESDAY...SO THIS WILL HELP PUSH A COLD FRONT THROUGH THE
REGION. THIS WILL TRANSITION WINDS TO MORE OF A NORTHERLY FLOW FOR
WEDNESDAY. THE FLOW WEAKENS THURSDAY...ALLOWING FOR SEA BREEZES
TO DEVELOP AS HIGH PRESSURE BUILDS IN FROM THE SOUTH AND WEST. THE
HIGH MOVES OFFSHORE FRIDAY INTO THE NEXT WEEKEND. ANOTHER COLD FRONT
APPROACHES INTO THE BEGINNING OF NEXT WEEKEND.

OUTSIDE OF WEDNESDAY...A GENERAL SOUTH TO SOUTHWEST FLOW DOMINATES
NEXT WEEK. THIS WILL RESULT IN TEMPERATURES WELL ABOVE SEASONAL
AVERAGES FOR THIS TIME OF YEAR. THE JET STREAM OVERALL KEEPS TO THE
NORTH OF THE REGION. TEMPERATURES WILL BE GENERALLY 5-10 DEGREES
ABOVE NORMAL MONDAY THROUGH WEDNESDAY AND A FEW DEGREES ABOVE
NORMAL WEDNESDAY NIGHT THROUGH SATURDAY.

ANOTHER CHANCE OF SHOWERS AND THUNDERSTORMS FROM NORTHWEST TO
SOUTHEAST TUESDAY INTO TUESDAY NIGHT WITH A LITTLE MORE SHEAR TO
WORK WITH. MAINLY DRY THEREAFTER WITH A SLIGHT CHANCE OF SHOWERS
AND THUNDERSTORMS TOWARDS END OF THE WORK WEEK INTO THE NEXT
WEEKEND WITH NEXT FRONT APPROACHING.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
HIGH PRES OVER THE WESTERN ATLANTIC WILL CONTINUE TO DEPART OVERNIGHT
AS A TROUGH OF LOW PRES APPROACHES FROM THE WEST LATE SUNDAY.

VFR CIGS TO START GRADUALLY LOWER THROUGH THE OVERNIGHT...WITH LOW
MVFR/LOCALLY IFR CIGS LIKELY LATE TONIGHT/SUN AM. HEATING SHOULD
RAISE CIGS TO VFR IN THE LATE MORNING/EARLY AFTN.

ISOLATED SHRA/TSRA POSSIBLE ALONG SEABREEZE BOUNDARIES SUN
AFTERNOON. OTHERWISE...INCREASING CHANCE FOR SHRA/TSTMS LATE
AFTN/EVE MAINLY FROM CITY TERMINALS AND POINTS N/W AS TROUGH
APPROACHES. TIMING MAY NEED TO BE ADJUSTED A FEW HOURS.

.OUTLOOK FOR 06Z MON THROUGH THU...
.SUN NIGHT-MON...NUMEROUS SHRA/EMBEDDED TSTMS AND OCNL MVFR
TRANSLATING EASTWARD ACROSS TERMINALS SUN NIGHT THROUGH MON
MORNING. ADDITIONAL SCT SHRA/TSRA POSSIBLE MON AFT/EVE. MVFR
STATUS/FOG POSSIBLE LATE MON NIGHT.
.TUE...SCT AFT/EVE SHRA/TSRA POSSIBLE.
.WED-THU...MAINLY VFR.

&&

.MARINE...
THE PRES GRADIENT WILL TIGHTEN TODAY AS LOW PRES PASSES TO THE N AND
HIGH PRES CONTINUES TO DEPART OUT TO SEA. THIS WILL RESULT IN AN
INCREASING SLY FLOW TODAY. SEAS ON THE OCEAN WATERS WILL BUILD IN
RESPONSE WITH SCA CONDS EXPECTED TO BE MET THIS EVENING AND CONTINUE
THROUGH THE NIGHT BEFORE SUBSIDING EARLY MON MORNING. THERE IS THE
POTENTIAL FOR 5 FT SEAS TO LINGER A FEW HOURS LONGER E OF MORICHES
INLET...BUT WILL END THE HAZARD AT 10Z FOR NOW. WIND GUSTS WILL ALSO
COME CLOSE TO 25 KT AT TIMES...MAINLY THIS EVE.

SUB-ADVSY CONDS ARE THEN EXPECTED THROUGH THE REMAINDER OF THE
FORECAST PERIOD WITH A FAIRLY WEAK GRADIENT OVER THE AREA.

&&

.HYDROLOGY...
DEEP MOISTURE IN PLACE WITH A SERIES OF SHORTWAVES ALOFT AND
SURFACE TROUGHS WILL INTERACT TO PRODUCE CONVECTION EACH
AFT/EVE OVER THE NEXT COUPLE OF DAYS WITH THE POTENTIAL FOR
LOCALIZED HEAVY RAINFALL. A LOCALIZED FLOOD THREAT REMAINS FOR
FLASH FLOODING. ON AVERAGE...LOOKING FOR ABOUT AN INCH OF
RAINFALL ACROSS THE BASINS...WITH SEVERAL INCHES POSSIBLE IN
STRONGER MORE ORGANIZED CONVECTION.


&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT MONDAY
     FOR ANZ350-353-355.

&&

$$

SYNOPSIS...DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...JM/DW
AVIATION...24
MARINE...24
HYDROLOGY...JM/DW





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