Storm Summary for Tropical Storm Flossie 17A

Sunday, July 28, 2013 at 8 PM HST

(Output from Hurrevac, based on Central Pacific Hurricane Center Forecast Advisory # 17A)

Flossie is currently a tropical storm on the Saffir-Simpson Hurricane Wind Scale, with maximum
sustained winds of 60 mph (52 kts), moving west at 18 mph. The estimated minimum central pressure is 996 mb. Tropical storm-force winds extend outward up to 160 miles (260 km) from the storm center. Certain coastal locations are under Tropical Storm Warning and Tropical Storm Watch as illustrated in the map below. The geographic extents of these watches and warnings are detailed in the advisory text at the end of this report.

 

Wind Analysis for Maui, HI

(Based upon Tropical Storm Flossie Advisory #17A)

Wind Probabilities

LANAI CITY, the closest reporting location, has within the 5-day forecast period of this advisory, a 3% chance of at least strong tropical storm-force (50kt/58mph) winds, and a 27% chance of at least tropical storm-force (34kt/39mph) winds.

Peak Wind*

Winds in Maui, HI are projected to peak at 41kt/47mph around 4:00 PM on Monday, July 29, 2013

Wind Arrival and Duration*

Tropical storm-force winds (34kt/39mph) are forecast to begin in Maui, HI on Monday, July 29, 2013 at 10:00 AM. Winds of this magnitude or higher are forecast to continue for 12 hours.

50kt/58mph winds are not forecast for Maui, HI.

64kt/74mph winds are not forecast for Maui, HI.

* These wind estimations are limited to the first 72 hours (3 days) following advisory issuance, and are subject to considerable forecast uncertainty and generalization, especially if the storm is distant. Maximum sustained winds (the highest surface wind maintained over a 1 minute period) are reported here. Wind gusts and winds at higher elevations will be greater.

Storm Summary for Tropical Storm Flossie #17A – Page 2

WTPA31 PHFO 290553

TCPCP1

BULLETIN

TROPICAL STORM FLOSSIE INTERMEDIATE ADVISORY NUMBER 17A

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP062013

800 PM HST SUN JUL 28 2013

…FLOSSIE CONTINUES TO BEAR DOWN ON THE MAIN HAWAIIAN ISLANDS…

SUMMARY OF 800 PM HST…0600 UTC…INFORMATION

———————————————-

LOCATION…19.5N 151.0W

ABOUT 265 MI…425 KM E OF HILO HAWAII

ABOUT 465 MI…750 KM ESE OF HONOLULU HAWAII

MAXIMUM SUSTAINED WINDS…60 MPH…95 KM/H

PRESENT MOVEMENT…W OR 265 DEGREES AT 18 MPH…30 KM/H

MINIMUM CENTRAL PRESSURE…996 MB…29.41 INCHES

WATCHES AND WARNINGS

——————–

CHANGES WITH THIS ADVISORY…

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT…

A TROPICAL STORM WARNING IS IN EFFECT FOR…

*HAWAII COUNTY

*MAUI COUNTY…INCLUDING THE ISLANDS OF MAUI…MOLOKAI…LANAI AND

KAHOOLAWE

*OAHU

A TROPICAL STORM WATCH IS IN EFFECT FOR

*KAUAI AND NIIHAU

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE

EXPECTED WITHIN THE WARNING AREA WITHIN 36 HOURS.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE

POSSIBLE WITHIN THE WATCH AREA WITHIN 48 HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA…PLEASE MONITOR

PRODUCTS FROM BY THE NATIONAL WEATHER SERVICE OFFICE IN HONOLULU.

DISCUSSION AND 48-HOUR OUTLOOK

——————————

AT 800 PM HST…0600 UTC…THE CENTER OF TROPICAL STORM FLOSSIE WAS

LOCATED NEAR LATITUDE 19.6 NORTH…LONGITUDE 151.0 WEST. FLOSSIE IS

MOVING TOWARD THE WEST NEAR 18 MPH…30 KM/H…AND THIS MOTION IS

EXPECTED TO CONTINUE THROUGH THE NEXT 48 HOURS.

MAXIMUM SUSTAINED WINDS ARE NEAR 60 MPH…95 KM/H…WITH HIGHER

GUSTS. SOME WEAKENING IS FORECAST DURING THE NEXT 48 HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 160 MILES…260 KM

FROM THE CENTER.

Storm Summary for Tropical Storm Flossie #17A – Page 3

ESTIMATED MINIMUM CENTRAL PRESSURE IS 996 MB…29.41 INCHES.

HAZARDS AFFECTING LAND

———————-

WIND…TROPICAL STORM CONDITIONS ARE EXPECTED TO REACH THE BIG

ISLAND LATE TONIGHT…MAUI COUNTY MONDAY MORNING AND OAHU MONDAY

NIGHT. TROPICAL STORM CONDITIONS ARE POSSIBLE ON KAUAI AND NIIHAU

MONDAY NIGHT…LASTING INTO TUESDAY.

RAINFALL…HEAVY RAINFALL IS EXPECTED TO BEGIN AS EARLY AS MONDAY

MORNING OVER HAWAII COUNTY AND MONDAY AFTERNOON OVER MAUI COUNTY…

WITH HEAVY RAIN SPREADING TO OAHU BY MONDAY NIGHT. FLOSSIE IS

EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF 6 TO 10 INCHES OVER

THE BIG ISLAND AND MAUI COUNTY…WITH ISOLATED MAXIMUM AMOUNTS OF 15

INCHES POSSIBLE…MAINLY WINDWARD. RAINFALL AMOUNTS OF 4 TO 8 INCHES

ARE POSSIBLE OVER OAHU…WITH ISOLATED MAXIMUM AMOUNTS OF 12 INCHES

POSSIBLE…MAINLY WINDWARD. THIS RAINFALL COULD CAUSE LIFETHREATENING

FLASH FLOODS AND MUD SLIDES…ESPECIALLY IN THE

MOUNTAINS.

SURF…DANGEROUSLY HIGH SURF IS STARTING TO HAMMER EAST FACING

SHORES OF THE BIG ISLAND. SURF WILL BUILD OVERNIGHT…WITH THE

LARGEST SURF EXPECTED MONDAY INTO TUESDAY. THE BIG SURF MAY CAUSE

COASTAL ROAD CLOSURES…EVEN BEFORE THE STORM ARRIVES. PLEASE SEE

THE LATEST HURRICANE LOCAL STATEMENT FOR INFORMATION SPECIFIC TO

YOUR AREA.

NEXT ADVISORY

————-

NEXT COMPLETE ADVISORY…1100 PM HST.

$$

FORECASTER DONALDSON

WWWW

WTPA41 PHFO 290240

TCDCP1

TROPICAL STORM FLOSSIE DISCUSSION NUMBER 17

NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP062013

500 PM HST SUN JUL 28 2013

ONCE AGAIN…SUBJECTIVE DVORAK ANALYSIS YIELDS A CONSISTENT 3.0…45

KT…FOR CURRENT FLOSSIE INTENSITY FROM PHFO…JTWC AND SAB. A LATE

MORNING ASCAT PASS SAMPLED THE EASTERN HALF OF FLOSSIE RATHER

WELL…INDICATING 45 KT AT THE FAR WESTERN EDGE OF THE PASS ALONG

THAT PORTION WHICH JUST MISSED THE CENTER. WE WILL KEEP 50 KT AS THE

INITIAL INTENSITY TO ACCOUNT FOR THIS NEAR MISS AND FOR THE

CONTINUED GOOD OVERALL SYSTEM ORGANIZATION. THE INITIAL 34 KT WIND

RADIUS ALONG THE SOUTHERN HALF OF FLOSSIE WAS INCREASED SLIGHTLY AS

WELL…THANKS TO ASCAT. SATELLITE LOOP SHOWS THAT FLOSSIE HAS LOST A

BIT OF LATITUDE SINCE MIDDAY…TRACKING SLIGHTLY SOUTH OF DUE WEST

AT 16 KT. THE LLCC IS LIKELY BENEATH A SMALL SET OF OVERSHOOTING

Storm Summary for Tropical Storm Flossie #17A – Page 4

TOPS WHICH HAVE FORMED THIS AFTERNOON. FLOSSIE HAS MOVED SLIGHTLY

FASTER THAN A COL NOTED IN 300 MB FLOW BETWEEN AN UPPER HIGH NEAR

KAUAI AND ANOTHER ONE NEAR 20N137W. SLIGHTLY STRONGER NORTHERLY FLOW

ALOFT WEST OF THE COL MAY ACCOUNT FOR THE SMALL SOUTHERLY TRACK

COMPONENT AND LOSS OF LATITUDE. ANOTHER POSSIBILITY IS THAT FLOSSIE

IS BEGINNING TO FEEL THE SPLIT FLOW EFFECTS OF THE BIG ISLAND…AT

LEAST ALONG ITS WESTERN PERIPHERY.

THE SYNOPTIC SCALE ENVIRONMENT THAT FLOSSIE IS MOVING INTO WILL

GRADUALLY CAUSE SYSTEM WEAKENING. SSTS WARM SLIGHTLY ALONG THE

PROJECTED PATH OF FLOSSIE…ESPECIALLY WEST OF THE MAIN HAWAIIAN

ISLANDS. HOWEVER…WATER VAPOR IMAGERY SHOWS THIS SYSTEM EMBEDDED IN

AN AREA OF INCREASINGLY DRY AIR ALOFT DUE TO SUBSIDENCE ASSOCIATED

WITH THE UPPER HIGH NEAR KAUAI NOTED EARLIER. AS FLOSSIE MOVES

WEST…THIS HIGH IS EXPECTED TO IMPOSE INCREASING NORTH TO

NORTHEASTERLY SHEAR ACROSS THE SYSTEM. MODELS CONTINUE TO INDICATE A

GRADUAL WEAKENING AND THE FORECAST TREND IS ABOUT THE SAME AS FROM

THE LAST CYCLE. THIS IS ALSO CLOSE TO SHIPS GUIDANCE…WHICH

ACTUALLY INDICATES INCREASED SHEAR AT ALMOST ALL TAU SINCE THE LAST

FORECAST CYCLE.

TRACK GUIDANCE REMAINS TIGHTLY CLUSTERED IN THE SHORT TERM…SHOWING

FLOSSIE NEAR THE BIG ISLAND AND MAUI MONDAY MORNING…THEN PASSING

SOUTH OF OAHU MONDAY NIGHT AND SOUTH OF KAUAI THROUGH TUESDAY. ONLY

BAMMS…STILL THE RIGHT OUTLIER…TAKES FLOSSIE JUST NORTH OF THE

ISLANDS ACROSS WINDWARD WATERS. THE LATEST TRACK FORECAST HAS BEEN

NUDGED SLIGHTLY SOUTHWARD FROM THE PREVIOUS TRACK THROUGH 36 HOURS

TO ACCOUNT FOR THE SMALL CHANGE IN SYSTEM MOTION SINCE THIS MORNING.

THIS TRACK STILL LIES NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE.

WHILE SYNOPTIC SCALE FEATURES LIKE UPPER HIGHS AND SHEAR ZONES PLAY

KEY ROLES IN TRACK AND INTENSITY FORECASTING…IT IS IMPORTANT TO

NOTE THAT FLOSSIE IS VERY LIKELY TO TRACK ACROSS AT LEAST A PORTION

OF THE BIG ISLAND OVER THE NEXT 36 HOURS…INTRODUCING THE

DIFFICULTY OF ACCOUNTING FOR TERRAIN EFFECTS ON SYSTEM TRACK AND

INTENSITY. POST-BIG ISLAND TRACK AND INTENSITY FORECASTS MAY BE

QUITE DIFFERENT ONCE THESE TERRAIN EFFECTS ARE KNOWN.

FORECAST POSITIONS AND MAX WINDS

INIT 29/0300Z 19.6N 150.2W 50 KT 60 MPH

12H 29/1200Z 19.6N 152.8W 50 KT 60 MPH

24H 30/0000Z 19.8N 156.1W 45 KT 50 MPH

36H 30/1200Z 20.0N 159.4W 35 KT 40 MPH

48H 31/0000Z 20.3N 162.8W 35 KT 40 MPH

72H 01/0000Z 20.7N 169.5W 30 KT 35 MPH

96H 02/0000Z 21.0N 176.4W 25 KT 30 MPH…POST-TROP/REMNT LOW

120H 03/0000Z…DISSIPATED

$$

FORECASTER POWELL