EPAC: JIMENA - Post-Tropical

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Re: EPAC: JIMENA - Tropical Storm

#361 Postby cycloneye » Mon Sep 07, 2015 10:32 pm

TROPICAL STORM JIMENA DISCUSSION NUMBER 50
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132015
500 PM HST MON SEP 07 2015

JIMENA APPEARS TO BE A MESSY...VERTICALLY TILTED SYSTEM LATE THIS
AFTERNOON. AN SSMI PASS AT 0021 UTC AND AN AMSU-B PASS AT 0014
UTC SEEM TO SUGGEST THAT THE LOW LEVEL CENTER MAY BE MORE TO THE
WEST OF WHERE THE CONVENTIONAL SATELLITE IMAGERY WOULD INDICATE...
WHICH COULD BE A MID-LEVEL CENTER. THE OFFICIAL POSITION IS A
COMPROMISE AMONG THESE VARIOUS POSITIONS. UNANIMOUS SUBJECTIVE
INTENSITY ESTIMATES OF 2.5...AND CIMSS ADT WAS 2.4. THIS...ALONG
WITH A SLOWLY DEGRADING BANDED STRUCTURE TO THE CONVECTION WHICH
MIGHT NOT EVEN BE FOLLOWING THE LOW LEVEL CENTER ANYMORE...IS THE
BASIS FOR LOWERING THE ADVISORY INTENSITY TO 40 KT.

THE INITIAL MOTION ESTIMATE IS A RATHER UNCERTAIN 290/6...DRIVEN
MAINLY BY A HIGH AT THE SURFACE AND ALOFT TO THE NORTHEAST OF THE
CYCLONE. JIMENA CONTINUES TO STRUGGLE THROUGH RELENTLESS WESTERLY
SHEAR OF 20 TO 30 KT...WHICH IS ONLY EXPECTED TO INCREASE ALONG THE
FORECAST TRACK. THIS SHEAR ALONG WITH MARGINAL SEA SURFACE
TEMPERATURES IS EXPECTED TO LEAD TO ADDITIONAL SLOW WEAKENING. THE
MODELS ARE CONTINUING TO SHOW THE LOW AND MID-LEVEL CIRCULATIONS
BECOMING INCREASINGLY DECOUPLED...AND SEPARATING IN ABOUT 24 HOURS
OR SO. AT THIS POINT JIMENA WILL BE STEERED BY THE SHALLOW LAYER
FLOW WHICH WILL TAKE THE CYCLONE JUST SOUTH OF DUE WEST FOR A TIME...
BEFORE LOW PRESSURE DEVELOPING NORTH OF LAYSAN PICKS UP WHAT
REMAINS OF THE CIRCULATION AND TURNS IT NORTHWARD ON DAYS 3-5. THE
TRACK GUIDANCE SHIFTED A LITTLE TO THE WEST AND SOUTH ONCE AGAIN...
LIKELY BECAUSE OF INCREASING CONFIDENCE IN JIMENA/S WEAKER STATE AT
THAT TIME...AND ADJUSTED OUR FORECAST TO MATCH THAT TREND AS WELL.
JIMENA IS STILL FORECAST TO BECOME A REMNANT LOW BY DAY 4...BUT THIS
COULD OCCUR SOONER.


FORECAST POSITIONS AND MAX WINDS

INIT 08/0300Z 26.5N 150.9W 40 KT 45 MPH
12H 08/1200Z 26.6N 151.8W 40 KT 45 MPH
24H 09/0000Z 26.4N 153.4W 35 KT 40 MPH
36H 09/1200Z 26.1N 154.9W 35 KT 40 MPH
48H 10/0000Z 26.0N 156.5W 30 KT 35 MPH
72H 11/0000Z 26.1N 159.3W 25 KT 30 MPH
96H 12/0000Z 26.5N 161.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 13/0000Z 29.0N 163.4W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
FORECASTER R BALLARD
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Re: EPAC: JIMENA - Tropical Storm

#362 Postby cycloneye » Tue Sep 08, 2015 5:09 am

TROPICAL STORM JIMENA DISCUSSION NUMBER 51
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132015
1100 PM HST MON SEP 07 2015

A NOTCH WITHIN THE MAIN DEEP CONVECTIVE CURVED BAND PROVIDES A BIT
OF CONFIDENCE IN THE POSITION OF JIMENA THIS EVENING. HOWEVER AFTER
WATCHING THE TIGHTNESS OF THE LOW CLOUD SWIRLS WEST OF THE HIGH
CLOUD CANOPY IN ANIMATION...AND TAKING THE HIGHLY SHEARED
ENVIRONMENT INTO ACCOUNT...WE SUSPECT THE LLCC LIES WEST OF THE
APPARENT MID AND UPPER LEVEL CIRCULATION NOTED BY THE SATELLITE
CENTERS. THE POSITION FOR THIS ADVISORY LIES JUST WEST OF THE
DEEPEST CONVECTION AT 0600 UTC...BENEATH THE REMAINING HIGH CLOUDS.
IF THESE CLOUDS WERE TO THIN SUFFICIENTLY OVERNIGHT...WE MIGHT GET A
PEEK AT AN EXPOSED LLCC. A VERY LATE 0503 UTC SSMIS PASS ADDS
CREDENCE TO THIS POSSIBILITY. SUBJECTIVE DVORAK SATELLITE INTENSITY
ESTIMATES WERE ALL 2.5...35 KT...FROM THE SATELLITE CENTERS.
UW-CIMSS ADT WAS ALSO 35 KT. WHILE IT WAS TEMPTING TO FOLLOW SUIT
AND WEAKEN JIMENA TO 35 KT...THE NEW BURST OF CONVECTION ALONG THE
CURVED BAND ACROSS THE NORTHEAST FLANK PROMPTS US TO MAINTAIN 40 KT
AS THE INITIAL INTENSITY FOR THIS ADVISORY.

OUR ASSUMPTION CONCERNING THE DISPLACEMENT OF THE MID AND UPPER
LEVEL CIRCULATION CENTER TO THE EAST OF THE LLCC WAS PROBABLY ALSO
TRUE SIX HOURS AGO. FORTUNATELY...THE 12 HOUR MOTION WAS 290/06 KT
AND WE WILL USE THIS AS INITIAL MOTION AS WELL. JIMENA REMAINS IN A
HOSTILE WEST TO SOUTHWEST SHEAR ENVIRONMENT...RANGING FROM 20 KT
FROM SHIPS TO 30 KT FROM UW-CIMSS. THIS IS FORECAST TO INCREASE TO
OVER 40 KT IN 48 HOURS...ACCORDING TO SHIPS...SO IT IS DIFFICULT TO
SEE HOW THIS SYSTEM COULD REMAIN INTACT THROUGH A FIVE DAY FORECAST
TRACK. NEVERTHELESS...THIS SEEMS TO BE THE SEASON FOR STUBBORNLY
RESILIENT STORMS. TRACK GUIDANCE SHIFTED A BIT TO THE WEST...BUT NO
FARTHER SOUTH...LIKELY ACCOUNTING FOR AN INCREASE IN FORECAST
FORWARD SPEED AS JIMENA DEVOLVES TO A LOW-LEVEL STEERED SYSTEM. THE
FORECAST TRACK WAS ADJUSTED A BIT TO THE NORTH FROM THE PREVIOUS ONE
TO ACCOUNT FOR INITIAL MOTION...BUT FOLLOWS THE PREVIOUS TRACK ALONG
THE SHAPE OF CONSENSUS GUIDANCE AFTERWARDS. WE MAY HAVE TO INCREASE
FORWARD SPEED AFTER 48 HOURS IN SUBSEQUENT ADVISORIES IF THE
WESTWARD GUIDANCE SHIFT PERSISTS.

JIMENA WILL GRADUALLY WEAKEN THROUGH THE NEXT FIVE DAYS...BECOMING
AN EXTRATROPICAL LOW BY DAY 4 IN OUR FORECAST. THE FORESEEN SHEAR
INCREASE BY DAY TWO MAY SHORTEN THIS LIFESPAN. THIS ADVISORY WEAKENS
JIMENA TO A DEPRESSION BY 36 HOURS...SLIGHTLY MORE QUICKLY THAN LAST
TIME. WHATEVER IS LEFT OF JIMENA WILL BE DRAWN POLEWARD ALONG THE
EASTERN FLANK OF LOW PRESSURE DEVELOPING NORTH OF THE NORTHWESTERN
HAWAIIAN ISLANDS FROM DAYS THREE TO FIVE.

FORECAST POSITIONS AND MAX WINDS

INIT 08/0900Z 26.8N 151.7W 40 KT 45 MPH
12H 08/1800Z 27.0N 152.8W 40 KT 45 MPH
24H 09/0600Z 26.8N 154.3W 35 KT 40 MPH
36H 09/1800Z 26.5N 155.8W 30 KT 35 MPH
48H 10/0600Z 26.3N 157.4W 30 KT 35 MPH
72H 11/0600Z 26.4N 160.4W 25 KT 30 MPH
96H 12/0600Z 27.9N 162.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 13/0600Z 30.4N 164.4W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
FORECASTER POWELL
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Re: EPAC: JIMENA - Tropical Storm

#363 Postby cycloneye » Tue Sep 08, 2015 10:43 am

TROPICAL STORM JIMENA DISCUSSION NUMBER 52
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132015
500 AM HST TUE SEP 08 2015

HIGH CLOUDS ACROSS THE SOUTHEAST QUADRANT OF JIMENA THINNED ENOUGH
OVER THE PAST SIX HOURS TO OFFER GOOD VIEWS OF LOW CLOUD SWIRLS IN
ANIMATION WHICH...WHEN ADDED TO ANALYSIS OF LOW CLOUD SWIRLS ACROSS
THE WEST SEMICIRCLE...CONTRIBUTE TO OVERALL FIX CONFIDENCE FOR THE
1200 UTC ANALYSIS CYCLE. HOWEVER...AN 0700 UTC ASCAT PASS ACROSS
JIMENA...RECEIVED A BIT TOO LATE FOR THE LAST ADVISORY...SHOWED A
SLIGHTLY MORE INTENSE SYSTEM AND PLACED THE LLCC FARTHER SOUTH AND
WEST THAN ESTIMATED VIA SATELLITE ANALYSIS ALONE. A 1 KM RESOLUTION
VIIRS IMAGE AT 1146 UTC ALLOWED A VIEW OF ALMOST ALL OF THE LOW
CLOUD CIRCULATION...SHOWING THE LLCC WAS INDEED NOTICEABLY WEST OF
ANY MID AND UPPER LEVEL CIRCULATION NOTED BY THE SATELLITE CENTERS.
SINCE THE FINAL 1200 UTC POSITION AND STRENGTH WOULD HAVE RESULTED
IN UNREPRESENTATIVE MOTION AND INTENSITY FLUCTUATIONS...WE
REANALYZED THE PREVIOUS 0600 UTC...0000 UTC AND 1800 UTC POSITIONS
AND INTENSITIES. SUBJECTIVE DVORAK SATELLITE INTENSITY ESTIMATES
WERE ONCE AGAIN ALL 2.5...35 KT...FROM THE SATELLITE CENTERS...WHILE
UW-CIMSS ADT ESTIMATED 40 KT. A RESPECTABLE SWATH OF 45 KT WINDS WAS
NOTED ACROSS THE NORTHEAST QUADRANT IN THE ASCAT PASS AND...AS A
RESULT OF THE REANALYSIS PROCESS...AN INITIAL INTENSITY OF 45 KT IS
ASSIGNED FOR THIS ADVISORY. IT IS LIKELY THAT JIMENA ACTUALLY
MAINTAINED A STEADY 45 KT INTENSITY OVER THE PAST 24 HOURS.

AFTER REANALYSIS...THE 12 HOUR MOTION IS 275/07 KT...SLIGHTLY FASTER
AND MORE WESTERLY THAN DEPICTED BEFORE. JIMENA IS IN AN INCREASINGLY
HOSTILE WEST TO SOUTHWEST SHEAR ENVIRONMENT...RANGING FROM 24 KT TO
32 KT...FROM SHIPS AND UW-CIMSS RESPECTIVELY. SINCE SHIPS FORECASTS
SHEAR INCREASING TO OVER 40 KT AT 48 HOURS AND OVER 50 KT AT 72
HOURS...IT IS ONCE AGAIN DIFFICULT TO SEE HOW THIS SYSTEM COULD
REMAIN INTACT THROUGH A FIVE DAY FORECAST TRACK. HOWEVER...JIMENA
HAS PROVEN TO BE QUITE RESILIENT SO FAR. CONSENSUS TRACK GUIDANCE
SHIFTED NOTICEABLE TO THE WEST...AND JUST SLIGHTLY TO THE
SOUTH...PROMPTING US TO ADD A A BIT OF FORWARD MOTION AND TO NUDGE
THE FORECAST TRACK TO THE LEFT AFTER 12 HOURS. A SMALL DEVIATION TO
THE RIGHT AT 12 HOURS WAS MADE TO ACCOUNT FOR INITIAL MOTION. THE
FINAL FORECAST TRACK FOLLOWS CONSENSUS MORE CLOSELY THAN
BEFORE...BUT REMAINS JUST TO THE RIGHT OF IT.

JIMENA IS FORECAST TO GRADUALLY WEAKEN THROUGH THE NEXT FIVE
DAYS...BECOMING AN EXTRATROPICAL LOW BY DAY 4. THE FORESEEN SHEAR
INCREASE BY DAY TWO MAY SHORTEN THIS LIFESPAN. THIS ADVISORY WEAKENS
JIMENA TO A DEPRESSION BY 36 HOURS...LIKE LAST TIME...IN SPITE OF
THE INITIAL INTENSITY BUMP. THIS FOLLOWS MOST GUIDANCE...INCLUDING
SHIPS...THROUGH 36 HOURS. HOWEVER...SHIPS THEN QUICKLY DISSIPATES
JIMENA AT 48 HOURS. WE ARE NOT QUITE THAT BOLD. EITHER
WAY...WHATEVER IS LEFT OF JIMENA WILL BE DRAWN POLEWARD ALONG THE
EASTERN FLANK OF LOW PRESSURE DEVELOPING NORTH OF THE NORTHWESTERN
HAWAIIAN ISLANDS FROM DAYS THREE TO FIVE.

FORECAST POSITIONS AND MAX WINDS

INIT 08/1500Z 26.5N 152.7W 45 KT 50 MPH
12H 09/0000Z 26.6N 153.8W 40 KT 45 MPH
24H 09/1200Z 26.1N 155.5W 35 KT 40 MPH
36H 10/0000Z 25.7N 157.2W 30 KT 35 MPH
48H 10/1200Z 25.5N 158.9W 30 KT 35 MPH
72H 11/1200Z 25.9N 162.2W 25 KT 30 MPH
96H 12/1200Z 27.6N 165.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 13/1200Z 30.5N 166.9W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$
FORECASTER POWELL
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#364 Postby Kingarabian » Tue Sep 08, 2015 3:42 pm

Wait. Why is the NHC issuing advisories on Jimena?

ZCZC HFOTCDCP4 ALL
TTAA00 PHFO DDHHMM

TROPICAL STORM JIMENA DISCUSSION NUMBER 53
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132015
ISSUED BY NWS NATIONAL HURRICANE CENTER MIAMI FL
1100 AM HST TUE SEP 08 2015

JIMENA IS A SHEARED CYCLONE AND CONSISTS OF A LARGE CIRCULATION OF
LOW CLOUDS WITH SOME PATCHES OF DEEP CONVECTION TO THE EAST OF
THE CENTER. GIVEN THE LACK OF DEEP THUNDERSTORM ACTIVITY NEAR THE
CENTER...THE SATELLITE INTENSITY ESTIMATES HAVE CONTINUED TO
DECREASE...AND THE INITIAL INTENSITY HAS BEEN LOWERED TO 40 KT. THE
GLOBAL MODELS SEPARATE THE LOW-LEVEL FROM THE MID-LEVEL CENTER AS
QUICKLY AS 48 HOURS, AND SHIPS GUIDANCE INDICATE THAT STRONG SHEAR
WILL CONTINUE TO IMPINGE ON THE CYCLONE. ON THIS BASIS...THE
OFFICIAL FORECAST CALLS FOR JIMENA TO BECOME A REMNANT LOW IN 48
HOURS OR SO. THE LOW COULD REMAIN LINGERING FOR A FEW MORE DAYS.

THE BEST ESTIMATE OF THE INITIAL MOTION IS TOWARD THE WEST OR 270
DEGREES AT 6 KT. SINCE JIMENA IS BECOMING A SHALLOW CYCLONE...IT
WILL LIKELY BE STEERED SLOWLY TOWARD THE WEST OR EVEN
WEST-SOUTHWEST BY THE LOW-LEVEL TRADE WINDS FOR THE NEXT 2
TO 3 DAYS. AFTER THAT TIME...THE REMNANT LOW WILL LIKELY TURN MORE
TO THE NORTHWEST AWAY FROM THE HAWAIIAN ISLANDS AS A NEW TROUGH
APPROACHES FROM THE WEST. THE OFFICIAL FORECAST IS VERY CLOSE TO THE
MULTI-MODEL CONSENSUS AND IS NOT TOO DIFFERENT FROM THE PREVIOUS
ONE.


FORECAST POSITIONS AND MAX WINDS

INIT 08/2100Z 26.5N 153.4W 40 KT 45 MPH
12H 09/0600Z 26.3N 154.7W 35 KT 40 MPH
24H 09/1800Z 25.9N 156.4W 30 KT 35 MPH
36H 10/0600Z 25.6N 1
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#365 Postby Yellow Evan » Tue Sep 08, 2015 3:52 pm

CPHC is doing software maintenance, so the NHC is their backup. :uarrow:
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Re: EPAC: JIMENA - Tropical Storm

#366 Postby cycloneye » Tue Sep 08, 2015 9:41 pm

TROPICAL STORM JIMENA DISCUSSION NUMBER 54
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132015
ISSUED BY NWS NATIONAL HURRICANE CENTER MIAMI FL
500 PM HST TUE SEP 08 2015

THERE HAVE NOT BEEN MANY CHANGES WITH JIMENA OVER THE PAST SEVERAL
HOURS WITH THE CENTER MOSTLY EXPOSED TO THE WEST OF A BLOB OF
CONVECTION. ALTHOUGH THE SATELLITE PRESENTATION IS NOT VERY
IMPRESSIVE...AN EARLIER ASCAT-B PASS SURPRISINGLY SHOWED MAXIMUM
WINDS OF ABOUT 50 KT. ASSUMING SOME SPIN DOWN OF THE VORTEX SINCE
THEN LEADS TO AN INITIAL INTENSITY ESTIMATE OF 45 KT FOR THIS
ADVISORY.

MODEL GUIDANCE SHOWS SHEAR INCREASING TO RATHER HIGH VALUES OVER THE
NEXT DAY OR SO...LIKELY CAUSING A DECREASE IN STRENGTH. THE ONE
CAVEAT IS THAT JIMENA IS EXPECTED TO BE MOVING OVER WARMER WATERS
AND INTO A MORE MOIST ATMOSPHERE ALOFT AS WELL...WHICH COULD TEMPER
THE WEAKENING RATE. THE OFFICIAL FORECAST FOLLOWS THE TREND OF THE
INTENSITY CONSENSUS AND THE PREVIOUS OFFICIAL FORECAST SHOWING SLOW
WEAKENING...ALTHOUGH THE VALUES ARE HIGHER BECAUSE OF THE INITIAL
INTENSITY. REMNANT LOW STATUS IS LIKELY IN A COUPLE OF DAYS DUE TO
THE PERSISTENT STRONG SHEAR.

VISIBLE IMAGES INDICATE THE CYCLONE HAS TURNED WEST-SOUTHWESTWARD
AND IS MOVING ABOUT 7 KT. THIS GENERAL MOTION IS LIKELY FOR THE
NEXT DAY OR SO...FOLLOWED BY A TURN TO THE WEST WHILE THE STORM
MOVES AROUND A RIDGE TO THE NORTH. JIMENA...OR ITS REMNANTS...
SHOULD TURN NORTHWESTWARD AWAY FROM THE HAWAIIAN ISLANDS AND
ACCELERATE IN A FEW DAYS AHEAD OF A MID-LATITUDE TROUGH. THE TROUGH
SHOULD THEN ABSORB THE LOW BY DAY 5. OVERALL THE MODELS ARE IN GOOD
AGREEMENT ON THIS SYNOPTIC PATTERN AND THE OFFICIAL FORECAST IS
SHIFTED A LITTLE TO THE SOUTH BASED ON THE LATEST CONSENSUS
GUIDANCE.

FORECAST POSITIONS AND MAX WINDS

INIT 09/0300Z 26.0N 153.9W 45 KT 50 MPH
12H 09/1200Z 25.7N 155.1W 40 KT 45 MPH
24H 10/0000Z 25.3N 156.7W 35 KT 40 MPH
36H 10/1200Z 25.1N 158.3W 30 KT 35 MPH
48H 11/0000Z 25.1N 159.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 12/0000Z 25.5N 161.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 13/0000Z 28.0N 163.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 14/0000Z...DISSIPATED

$$
FORECASTER BLAKE
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#367 Postby Kingarabian » Tue Sep 08, 2015 9:52 pm

Man I wish the NHC always did the advisories for the CPAC.
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#368 Postby Yellow Evan » Tue Sep 08, 2015 9:54 pm

Don't know why they didn't go 50-55 given the ASCAT low bias.
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#369 Postby Yellow Evan » Wed Sep 09, 2015 7:55 am

For whatever reason, there was no advisory by the CPHC at 9z...
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Re: EPAC: JIMENA - Tropical Storm

#370 Postby wxman57 » Wed Sep 09, 2015 9:56 am

And none at 15Z. Jimena appears to be either a depression or remnant low now.
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Re: EPAC: JIMENA - Tropical Storm

#371 Postby supercane » Wed Sep 09, 2015 10:44 am

339
WTPA44 PHFO 091441
TCDCP4

TROPICAL DEPRESSION JIMENA DISCUSSION NUMBER 56
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132015
500 AM HST WED SEP 09 2015

JIMENA IS COMPLETELY DEVOID OF DEEP CONVECTION IN THE VICINITY OF
ITS LOW LEVEL CIRCULATION /LLCC/ EARLY THIS MORNING. AS A RESULT...
THE LATEST UW-CIMSS INTENSITY ESTIMATE IS 1.5/25 KT. THE CURRENT
SUBJECTIVE DVORAK INTENSITY ESTIMATES ARE 2.0/30 KT FROM SAB AND
PHFO...AND 1.5/25 KT FROM JTWC. THEREFORE...WE HAVE LOWERED THE
INITIAL INTENSITY TO 30 KT FOR THIS ADVISORY.

THE INITIAL MOTION OF THE LLCC IS 255/08 KT FOR THIS ADVISORY. THIS
WEST-SOUTHWEST MOTION...WHICH IS DUE TO STEERING BY DEEP LAYER
RIDGING TO THE NORTH OF THE TROPICAL DEPRESSION...IS EXPECTED TO
CONTINUE DURING THE NEXT 12-24 HOURS. AS JIMENA STARTS TO ROUND THE
RIDGE...IT WILL GRADUALLY TURN TOWARD THE WEST DURING THE 24-36 HOUR
TIME PERIOD...AND TOWARD THE WEST-NORTHWEST DURING THE 36-48 HOUR
INTERVAL. THE GLOBAL FORECAST MODELS SHOW AN UPPER LEVEL TROUGH
DIGGING TOWARD JIMENA WILL CAUSE THE SYSTEM TO ACCELERATE TOWARD THE
NORTHWEST BEYOND 72 HOURS. THE LATEST FORECAST TRACK IS VERY CLOSE
TO THE PREVIOUS WITH SOME SLIGHT NUDGING TO MORE CLOSELY FOLLOW THE
LATEST TVCN AND GFEX GUIDANCE.

THE LATEST ESTIMATES OF ENVIRONMENTAL VERTICAL WIND SHEAR IN THE
VICINITY OF JIMENA FROM THE UW-CIMSS AND SHIP GUIDANCE INDICATE IT
IS GREATER THAN 30 KT FROM THE WEST. THIS STRONG SHEAR IS FORECAST
TO CONTINUE FOR THE NEXT FEW DAYS...SO THE CHANCES OF JIMENA
RECOVERING DEEP CONVECTION NEAR ITS INNER CORE ARE BECOMING
INCREASINGLY UNLIKELY. THEREFORE...THE LATEST INTENSITY FORECAST
FOLLOWS THE INTENSITY CONSENSUS GUIDANCE...WHICH SHOWS STEADY
WEAKENING DURING THE NEXT 24 HOURS...WITH JIMENA WEAKENING TO A
REMNANT LOW WITHIN THE NEXT 36 HOURS.


FORECAST POSITIONS AND MAX WINDS

INIT 09/1500Z 25.5N 155.8W 30 KT 35 MPH
12H 10/0000Z 25.2N 156.9W 30 KT 35 MPH
24H 10/1200Z 25.0N 158.5W 25 KT 30 MPH
36H 11/0000Z 25.2N 159.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 11/1200Z 25.4N 160.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 12/1200Z 27.0N 163.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 13/1200Z...DISSIPATED
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Re: EPAC: JIMENA - Tropical Depression

#372 Postby cycloneye » Wed Sep 09, 2015 4:12 pm

TROPICAL DEPRESSION JIMENA DISCUSSION NUMBER 57
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132015
1100 AM HST WED SEP 09 2015

JIMENA CONTINUES TO BE DEVOID OF DEEP CONVECTION THIS MORNING...AND
IS NOW JUST A LOW CLOUD SWIRL WITH ISOLATED TOWERING CUMULUS WELL
REMOVED FROM THE CENTER IN THE NORTHEAST QUADRANT. DVORAK DATA-T
VALUES ARE UNAVAILABLE FROM THE FIX AGENCIES DUE TO THE LACK OF
DEEP CONVECTION...WITH A CURRENT INTENSITY ESTIMATE OF 2.0/30 KT
FROM PHFO HELPING TO SUPPORT AN INITIAL INTENSITY OF 30 KT FOR THIS
ADVISORY.

NOW THAT JIMENA IS A SHALLOW SYSTEM...IT IS BEING DRIVEN BY THE LOW-
LEVEL FLOW AROUND A HIGH CENTERED FAR TO THE NORTHEAST...WITH AN
INITIAL MOTION ESTIMATE OF 250/08 KT. THE HIGH IS NOT EXPECTED TO
MOVE MUCH OVER THE NEXT SEVERAL DAYS...AND JIMENA IS FORECAST TO
MOVE GENERALLY WESTWARD TO THE SOUTH OF THE LOW-LEVEL RIDGE INTO
FRIDAY. ALTHOUGH THE OFFICIAL 72 HOUR FORECAST INDICATES
DISSIPATION...BETWEEN THE 48 AND 72 HOUR FORECAST POSITIONS...JIMENA
WILL MOVE ON AN INCREASINGLY NORTHERLY TRAJECTORY AS THE RIDGE
ERODES AND POST-TROPICAL JIMENA GETS ENGULFED IN THE FLOW AROUND A
DEVELOPING DEEP-LAYER LOW TO THE NORTHWEST. THIS IS LINE WITH THE
RELIABLE DYNAMIC MODEL GUIDANCE.

ALREADY HOSTILE ENVIRONMENTAL CONDITIONS...WITH SHEAR VALUES BETWEEN
30 AND 40 KT AND DRY MID-LEVEL AIR...WILL BECOME INCREASINGLY
HOSTILE OVER THE NEXT COUPLE OF DAYS. THE CLOCK IS TICKING ON JIMENA
AS A TROPICAL CYCLONE...AND IF CONVECTION DOES NOT DEVELOP NEAR THE
CENTER...IT WILL NOT BE LONG BEFORE IT CAN BE DECLARED A
POST-TROPICAL LOW. THE UPDATED FORECAST INDICATES THAT THIS WILL
OCCUR BY TOMORROW MORNING...BUT THIS MAY BE SOMEWHAT CONSERVATIVE
GIVEN CURRENT TRENDS.


FORECAST POSITIONS AND MAX WINDS

INIT 09/2100Z 24.9N 156.4W 30 KT 35 MPH
12H 10/0600Z 24.7N 157.7W 30 KT 35 MPH
24H 10/1800Z 24.6N 159.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
36H 11/0600Z 24.8N 160.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 11/1800Z 25.0N 162.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 12/1800Z...DISSIPATED

$$

FORECASTER BIRCHARD
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