CPAC: MALIA - Post-Tropical

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supercane
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Re: CPAC: MALIA - Tropical Storm

#41 Postby supercane » Tue Sep 22, 2015 11:12 am

WTPA45 PHFO 221441
TCDCP5

TROPICAL STORM MALIA DISCUSSION NUMBER 16
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP052015
500 AM HST TUE SEP 22 2015

MALIA IS NEARING THE END OF ITS LIFESPAN AS A TROPICAL SYSTEM THIS
MORNING...BUT WE ARE NOT QUITE DONE WITH IT YET. THE LLCC IS MOVING
FARTHER AWAY FROM THE DEEPEST CONVECTION...WHICH CONTINUES TO FLARE
ACROSS THE NORTHWESTERN HAWAIIAN ISLANDS BETWEEN MARO REEF AND
FRENCH FRIGATE SHOALS. THE 250 NM SPAN BETWEEN THE LLCC AND DEEP
CONVECTION PREVENTS SAB AND PHFO FROM PROVIDING SATELLITE-DERIVED
INTENSITY ESTIMATES...WHILE JTWC TURNED IN A 25 KT INTENSITY.
HOWEVER...AN 0851 UTC ASCAT PASS SHOWED A SWATH OF 35 KT WINDS 60 TO
150 NM OUT FROM THE LLCC WITHIN THE NORTHEAST QUADRANT. THIS PROMPTS
US TO KEEP INITIAL INTENSITY AT 35 KT...BUT THE SWATH LOCATION
ALLOWS US TO CANCEL ALL TROPICAL STORM WARNINGS ACROSS THE
NORTHWESTERN HAWAIIAN ISLANDS.

THE EXPOSED LLCC IS NOW MOVING AT 325/12 KT...REPRESENTING AN
INCREASE IN FORWARD SPEED SINCE LAST EVENING. OVERALL MOTION
CONTINUES TO BE INFLUENCED BY A COMBINATION OF A RIDGE NORTHEAST OF
THIS SYSTEM AND DEEP LOW PRESSURE WEST OF THE DATELINE. MALIA IS
EXPECTED TO CONTINUE MOVING GENERALLY TOWARD THE NORTH NORTHWEST
THROUGH ITS TRANSITION TO AN EXTRATROPICAL GALE LOW...THEN
DISSIPATION AT 72 HOURS.

MALIA WILL STRENGTHEN A BIT AS IT UNDERGOES EXTRATROPICAL
TRANSITION...REACHING 45 KT AT 24 HOURS. BY THEN...THE ASSOCIATED
WIND FIELD WILL BE EVEN MORE ASSYMETRIC THAN IT IS
NOW...BRIEFLY ENJOYING THE BENEFITS OF A STEEPENED PRESSURE GRADIENT
BETWEEN MIDLATITUDE FEATURES. BEYOND 12 HOURS...THE TRACK AND
INTENSITY FORECAST WAS CONDUCTED IN COLLABORATION WITH THE OCEAN
PREDICTION CENTER...OPC.

THE TROPICAL STORM WARNING FOR PORTIONS OF THE PAPAHANAUMOKUAKEA
MARINE NATIONAL MONUMENT FROM FRENCH FRIGATE SHOALS TO MARO REEF TO
LISIANSKI ISLAND IS CANCELLED. THE 0851 UTC ASCAT PASS SHOWED THAT
THE SWATH OF TROPICAL STORM FORCE WINDS IS NOW COMFORTABLY NORTH OF
ALL THE NORTHWESTERN HAWAIIAN ISLANDS.


FORECAST POSITIONS AND MAX WINDS

INIT 22/1500Z 28.7N 173.4W 35 KT 40 MPH
12H 23/0000Z 31.8N 175.7W 40 KT 45 MPH...BECOMING EXTRATROPICAL
24H 23/1200Z 36.0N 178.2W 45 KT 50 MPH...POST-TROP/EXTRATROP
36H 24/0000Z 39.7N 178.3E 45 KT 50 MPH...POST-TROP/EXTRATROP
48H 24/1200Z 42.7N 174.9E 40 KT 45 MPH...POST-TROP/EXTRATROP
72H 25/1200Z...DISSIPATED

$$
FORECASTER POWELL
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Re: CPAC: MALIA - Tropical Storm

#42 Postby Yellow Evan » Tue Sep 22, 2015 2:16 pm

wxman57 wrote:Quite a bit more sheared than Ida. Weak swirl of a LLC is over 200 miles NW of dissipating convection. ASCAT from 9Z indicates no TS winds. CPHC's intensity was based on an ASCAT pass from yesterday afternoon (they admitted it was "dated"). It's a remnant low now - doesn't qualify for a TD with no convection within 200 miles of a weak swirl.

Image


Except that you have to give it a chance for this to re-develop deep convection.
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Re: CPAC: MALIA - Tropical Storm

#43 Postby supercane » Tue Sep 22, 2015 5:27 pm

WTPA45 PHFO 222031
TCDCP5

POST-TROPICAL CYCLONE MALIA DISCUSSION NUMBER 17
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP052015
1100 AM HST TUE SEP 22 2015

MALIA HAS BEEN A LOW LEVEL CLOUD SWIRL WITH NO DEEP CONVECTION NEAR
THE CENTER FOR ALMOST 24 HOURS. THUS...MALIA IS BEING DECLARED A
POST-TROPICAL REMNANT LOW. THE CYCLONE IS CROSSING THE SST GRADIENT
TOWARD MUCH COOLER WATER AND THE CIMSS 1800 UTC ANALYSIS SHOWED
ABOUT 42 KT OF VERTICAL WIND SHEAR SO REDEVELOPMENT IS HIGHLY
UNLIKELY. FURTHERMORE...THE CENTER IS MOVING AT 345/16 KT TOWARD A
LARGE MID-LATITUDE LOW PRESSURE SYSTEM WEST OF THE DATELINE. THE
REMNANTS OF MALIA ARE EXPECTED TO BE ABSORBED BY THIS LARGER LOW
WITHIN THE NEXT 12 TO 24 HOURS. IN THE SHORT TERM...THE INITIAL WIND
FIELD WILL REMAIN ELEVATED AT 30 TO 35 KT IN THE NORTHEASTERN
QUADRANT DUE TO A STRONG PRESSURE GRADIENT BETWEEN MALIA/S REMNANT
AND A STRONG HIGH PRESSURE RIDGE TO THE NORTH AND NORTHEAST. THESE
WINDS WILL SLOWLY WEAKEN AS THE REMNANT LOW SPINS DOWN.

THIS IS THE LAST FORECAST/ADVISORY PACKAGE ISSUED BY THE CENTRAL
PACIFIC HURRICANE CENTER ON MALIA. FOR ADDITIONAL INFORMATION ON THE
REMNANT LOW...PLEASE SEE HIGH SEAS FORECASTS ISSUED BY THE NATIONAL
WEATHER SERVICE HONOLULU UNDER AWIPS HEADER HFOHSFNP AND WMO HEADER
FZPN40 PHFO.


FORECAST POSITIONS AND MAX WINDS

INIT 22/2100Z 29.7N 173.4W 35 KT 40 MPH
12H 23/0600Z 32.6N 174.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
24H 23/1800Z...DISSIPATED

$$
FORECASTER KODAMA
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