FXUS61 KOKX 061325
AFDOKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE UPTON NY
925 AM EDT SAT SEP 6 2008
.SYNOPSIS...
TROPICAL STORM HANNA WILL RACE NORTHEAST FROM NORTH CAROLINA
THIS MORNING TO LONG ISLAND SOUND JUST AFTER MIDNIGHT
TONIGHT...AND TO NOVA SCOTIA BY SUNDAY AFTERNOON. PLEASE REFER TO
THE LATEST STATEMENT FROM THE NATIONAL HURRICANE CENTER FOR
FURTHER DETAILS ON HANNA.
WEAK HIGH PRESSURE BUILDS IN FROM THE GREAT LAKES BEHIND HANNA
SUNDAY AND SUNDAY NIGHT...THEN MOVES OFFSHORE MONDAY. A WARM FRONT
CROSS THE REGION MONDAY NIGHT AND TUESDAY MORNING...FOLLOWED BY A
COLD FRONT TUESDAY AFTERNOON AND EVENING. HIGH PRESSURE THEN
BUILDS IN FROM THE GREAT LAKES FROM LATE TUESDAY NIGHT INTO
THURSDAY...THEN SLIDES OFF THE NEW ENGLAND COAST THURSDAY
NIGHT AND DOMINATES OUR WEATHER TO CLOSE THE WORK WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLIER RAINFALL OF AN INCH TO ONE AND A HALF INCHES. RADAR
ESTIMATES SLIGHTLY HIGH. SHOULD HAVE A LULL IN THE PRECIPITATION
UNTIL HANNAS OUTER BANDS BEGIN TO IMPACT US BY LATE MORNING...WITH
ITS MAIN RAIN SHIELD ENVELOPING THE REGION BY LATE AFTERNOON AND
CONTINUING THROUGH THE EVENING. WITH 500-1000 J/KG OF CAPE PROGGED
OVER THE REGION WILL HAVE ENOUGH LOW LEVEL INSTABILITY OVER THE
REGION...COUPLED WITH HIGH LOW LEVEL HELICITIES THIS AFTERNOON AND
EVENING...THAT ISOLATED TORNADIC THREAT CANNOT BE RULED OUT (NOTE
SPC HAS SLIGHT RISK OVER MOST OF LONG ISLAND AND SE CT DUE TO 5%
TORNADO PROBABILITY AND 2 PCT PROBABILITY OVER REMAINDER OF CWA
EXCEPT FAR WESTERN ORANGE COUNTY. FLOOD POTENTIAL DUE TO HEAVY
RAINFALL WILL BE DISCUSSED IN THE HYDROLOGY SECTION.
WITH EXPECTED TRACK ACROSS NEW YORK HARBOR...MOST OF WESTERN SECTIONS
OF LONG ISLAND THEN SOUTHERN LONG ISLAND SOUND TONIGHT...EXPECT
STRONGEST WINDS OVER THE SOUTH SHORE OF LONG ISLAND...THE TWIN
FORKS...AND FAR SE CT WITH SUSTAINED WINDS OF 40-45 MPH AND GUSTS
OF 50-55 MPH POSSIBLE NEAREST AND JUST AHEAD OF THE CENTER NEAR
THE IMMEDIATE COAST...WITH LESSER VALUES JUST INLAND. BECAUSE OF
THE WESTWARD SHIFT OF THE TRACK...REMEMBER IT IS EXPECTED TO BE
PARABOLIC FROM SE VA TO LONG ISLAND SOUND...AND HAVE LITTLE IF ANY
ADDITIONAL TIME OVER THE ATLANTIC AS A RESULT...HAVE DECIDED TO
CONVERT THE TROPICAL STORM WIND WATCH TO A TROPICAL STORM WIND
WARNING AT THIS TIME.
BASED ON FORECAST TRACK...AND MODELS SUGGESTING RAPID DRYING
BEHIND HANNA...BRING PRECIPITATION TO AN END FAIRLY QUICKLY FROM
SW TO NE AFTER MIDNIGHT TONIGHT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
SUNDAY SHOULD BE A DRY DAY...WITH DIMINISHING WINDS. 850
TEMPERATURES AROUND 15C SHOULD ENABLE NYC METRO AREA TO REACH INTO
THE MID 80S...WITH MOST OTHER AREAS RANGING FROM AROUND 80 TO THE
LOWER 80S. (WNW BOUNDARY LAYER FLOW SHOULD BE STRONG ENOUGH TO
PRECLUDE A SEA BREEZE). SUNDAY NIGHT AND MONDAY WILL ALSO BE
DRY...BUT WITH SLIGHT RIDGING ALOFT...BUT SLIGHTLY COOLER AIR
MOVING IN AT LOWER LEVELS...SO MONDAY SHOULD BE A COUPLE OF
DEGREES COOLER THAN SUNDAY...WITH NEAR TO SLIGHTLY BELOW NORMAL
LOWS SUNDAY NIGHT AS THE HIGH TRANSITS OVER THE TRI-STATE
PRODUCING GOOD RADIATIONAL COOLING CONDITIONS.
A WARM FRONT BEGINS TO LIFT NEW THROUGH THE AREA MONDAY NIGHT
WARRANTING SLIGHT CHANCE POPS (EXCEPT LOW END CHC FAR W). WITH
LOWS RETURNING TO ABOVE NORMAL LEVELS...ESPECIALLY OVER THE
WESTERN HALF OF THE CWA.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
LITTLE IF ANY CHANGES MADE IN THE EXTENDED...WITH THOSE MADE
PRIMARILY TO BETTER AGREE WITH SURROUNDING OFFICES. PREVIOUS
DISCUSSION FOLLOWS.
FCST BASED ON HPC.
COLD FRONT MOVES INTO THE REGION MON NIGHT...TOUCHING OFF SCATTERED
SHOWERS MON NIGHT AND TUE AS IT MOVES ACROSS THE CWA. PRECIP WINDS
DOWN TUE NIGHT AS THE FRONT DEPARTS AND STRONG HIGH PRES BUILDS INTO
THE CENTRAL PORTION OF THE COUNTRY AND BUILDS EAST ON WED AND THEN
MOVES OFFSHORE ON THU.
WARM FRONT THEN PUSHES NORTH THU NIGHT AS A STRONG COLD FRONT TRACKS
EAST THROUGH THE COUNTRY...MOVING INTO THE REGION ON FRI.
HIGHS WILL GENERALLY BE IN THE UPPER 70S TO AROUND 80 ON TUE...BUT
BEHIND THE FRONT...A COOLER AND DRYER AIRMASS WILL OVERSPREAD THE
REGION. HIGHS FROM WED THROUGH FRI WILL GENERALLY TOP OFF IN THE LOW
TO MID 70S.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
FOG/LOW STRATUS IMPACTING MOST TERMINALS THIS MORNING DUE TO
ABUNDANT TROPICAL MOISTURE IN ADVANCE OF TS HANNA. WINDS ARE
GENERALLY SOUTH...AND WILL BACK TO SE AND INCREASE IN SPEEDS
THROUGHOUT THE MORNING.
EXTRAPOLATING THE INITIAL RAN BANDS ASSOCIATED WITH HANNA GIVES AN
ARRIVAL TIME FOR NYC TERMINALS ABOUT 15Z. THE RAIN MAY ACTUALLY
IMPROVE VIS A BIT BY WASHING OUT THE FOG...BUT DO NOT EXPECT
BETTER THEN HIGH END IFR FOR THE REMAINDER OF TODAY.
WINDS TURN TO E LATE IN THE AFTERNOON TO EARLY EVENING AND
INCREASE. CLOSEST APPROACH OF THE CENTER OF HANNA...AND HIGHEST
WINDS SPEEDS WILL BE BETWEEN 00Z AND 06Z. GREATEST THREAT FOR WIND
SHEAR IS DURING THIS PERIOD AS WELL. THIS IS NOT DETAILED IN THE
TAFS AS OF YET...BUT WILL IN LATER VERSIONS.
AS THE CENTER PASSES EAST OF THE TAF SITES...THEY WILL HAVE
IMPROVING CONDITIONS WITH A DECREASING NW WIND.
OUTLOOK FOR 12Z SATURDAY THROUGH WEDNESDAY...ALL NYC/SE NY/NJ TERMINALS
IMPROVING TO VFR BY 12Z SUNDAY. TROPICAL STORM FORCE S-SE WINDS
WILL BE CLOSE TO THEIR PEAK AT KGON INITIALLY...BUT WILL VEER TO
NE QUICKLY AS THE CENTER PASSES OFF TO THE NE.
HIGH PRESSURE AND VFR MONDAY. SHOWERS/TSTMS COULD PRODUCE SUB VFR
CONDITIONS ON TUE AHEAD OF AN APPROACHING COLD FRONT.
&&
.MARINE...
TROPICAL STORM HANNA WILL IMPACT THE AREA WATERS THROUGH LATE
SUNDAY. BASED ON THE CURRENT FORECAST TRACK...EXPECT LONG PERIOD
SOUTHERLY SWELLS TO CONTINUE FOR MOST OF TODAY GRADUALLY INCREASING
TO 8 TO 10 FT BY LATE AFTERNOON. A MORE RAPID BUILDING EXPECTED
THROUGH ABOUT 03Z TO 12 TO 16 FT AND TRANSITIONS TO MORE OF A
COMBINED SEA AND SHORTER PERIOD. WNA4 BLENDED WITH THE CURRENT
FORECAST WAS USED...AND TWEAKED TO ACCOUNT FOR A FASTER THAN
OBSERVED NORTHWARD PROPAGATION IN THE MODEL.
WINDS INCREASE SIGNIFICANTLY AFTER 18Z TODAY. BASED ON THE LATEST
NHC GUIDANCE...EXPECT 45KTS SUSTAINED WITH GUSTS TO 55KTS OVER OPEN
OCEAN WATERS. EASTERN LI SOUND SHOULD SEE SIMILAR WINDS...WITH
SOMEWHAT OF A DECREASE ACROSS THE WESTERN SOUND.
HIGH SURF AND DANGEROUS RIP CURRENTS WILL PRECEDE THE SYSTEM SAT AND
LIKELY CONTINUE INTO SUN.
BOATERS ARE URGED TO REMAIN IN PORT WHILE TROPICAL STORM WARNINGS
ARE IN EFFECT...AND TO MONITOR NWS AND NHC STATEMENTS ON HANNA.
SEAS ON THE OCEAN WILL BE SLOW TO SUBSIDE BELOW ADVISORY CRITERIA...
AND CAN EXPECT SEAS ABOVE CRITERIA LASTING THROUGH MON. ANOTHER COLD
FRONT WILL MOVE ACROSS THE REGION ON TUE...POSSIBLY RESULTING IN SCA
CONDITIONS TUE THROUGH WED. IN ADDITION...LONG PERIOD SWELLS FROM
HURRICANE IKE MAY IMPACT THE LOCAL WATERS THROUGH MUCH OF NEXT WEEK.
&&
.HYDROLOGY...
ONE TO ONE AND A HALF INCHES FELL EARLIER THIS MORNING. RADAR
ESTIMATE SLIGHTLY HIGH. AN ADDITIONAL 4 TO 6 INCHES OF RAINFALL IS
EXPECTED FROM HANNA THROUGH TONIGHT...WITH LOCALLY HIGHER
AMOUNTS...UP TO 10 INCHES POSSIBLE WHERE THE STRONGEST BANDS END
UP GOING OVER. IN THESE BANDS...RAINFALL RATES IN EXCESS OF 2
INCHES AN HOUR ARE POSSIBLE. AS A RESULT HAVE CONTINUED THE FLOOD
WATCH FOR THE ENTIRE AREA. THE HEAVIEST RAINFALL IS CURRENTLY
EXPECTED ALONG AN AXIS RUNNING FROM NYC INTO SOUTHERN CONNECTICUT
ZONES (BASICALLY JUST TO THE LEFT OF THE FORECAST TRACK). FLASH
FLOODING IS ALSO POSSIBLE...ESPECIALLY IN URBAN AREAS.
&&
.TIDES/COASTAL FLOODING...
CURRENT DATA INDICATES THAT COASTAL FLOODING DUE TO HIGH TIDES
WILL NOT BE WIDESPREAD...AS ASTRONOMICAL TIDE LEVELS ARE
LOW...LIMITING THE IMPACT OF A PROJECTED 1 TO 2 FOOT TIDAL
DEPARTURE TO AT MOST LOW END MINOR FLOODING AT ISOLATED AREAS.
MOST TIDAL LOCATIONS IN THE REGION REQUIRE 2 TO 3 FT DEPARTURES
TO REACH MINOR FLOOD LEVELS. IN ADDITION...HIGH SURF OF 10 PLUS
FEET WILL PRODUCE BEACH EROSION ACROSS BEACHES ALONG THE SOUTH
SHORE OF LONG ISLAND LATER TODAY AND THIS EVENING.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...FLOOD WATCH THROUGH SUNDAY MORNING FOR CTZ005>012.
TROPICAL STORM WARNING FOR CTZ009>012.
TROPICAL STORM WIND WARNING FROM 2 PM THIS AFTERNOON TO 8 AM
EDT SUNDAY FOR CTZ005>008.
NY...FLOOD WATCH THROUGH SUNDAY MORNING FOR NYZ067>081.
TROPICAL STORM WARNING FOR NYZ071>081.
TROPICAL STORM WIND WARNING FROM 2 PM THIS AFTERNOON TO 8 AM
EDT SUNDAY FOR NYZ067>070.
NJ...FLOOD WATCH THROUGH SUNDAY MORNING FOR NJZ002>006-011.
TROPICAL STORM WARNING FOR NJZ005-006-011.
TROPICAL STORM WIND WARNING FROM 2 PM THIS AFTERNOON TO 8 AM
EDT SUNDAY FOR NJZ002>004.
MARINE...TROPICAL STORM WARNING FOR ANZ330-335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...PFM/PW
NEAR TERM...PFM/PW
SHORT TERM...PFM
LONG TERM...MPS/PFM
AVIATION...BS
MARINE...BS
HYDROLOGY...PFM/PW
TIDES/COASTAL FLOODING...
Back to Main Forecast Discussion Page |
