EPAC: MIRIAM - Post-Tropical

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Re: EPAC: MIRIAM - Hurricane

#81 Postby cycloneye » Sun Sep 23, 2012 9:40 pm

BULLETIN
HURRICANE MIRIAM ADVISORY NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
800 PM PDT SUN SEP 23 2012

...MIRIAM NOW A HURRICANE AND STRENGTHENING RAPIDLY...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...16.8N 111.3W
ABOUT 430 MI...695 KM SSW OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...90 MPH...150 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...979 MB...28.91 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 800 PM PDT...0300 UTC...THE CENTER OF HURRICANE MIRIAM WAS
LOCATED NEAR LATITUDE 16.8 NORTH...LONGITUDE 111.3 WEST. MIRIAM IS
MOVING TOWARD THE NORTHWEST NEAR 12 MPH...19 KM/H. THIS GENERAL
MOTION WITH A REDUCTION IN FORWARD SPEED IS EXPECTED DURING THE
NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS ARE NEAR 90 MPH...150 KM/H...WITH HIGHER
GUSTS. MIRIAM IS A CATEGORY ONE HURRICANE ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE. ADDITIONAL STRENGTHENING IS FORECAST DURING
THE NEXT DAY OR SO.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 25 MILES...35 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 105
MILES...165 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 979 MB...28.91 INCHES.


HAZARDS AFFECTING LAND
----------------------
NONE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...200 AM PDT.

$$
FORECASTER CANGIALOSI


HURRICANE MIRIAM DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
800 PM PDT SUN SEP 23 2012

MIRIAM HAS STRENGTHENED RAPIDLY DURING THE LAST 6 HOURS OR SO. AN
EYE...WHICH HAD BEEN EVIDENT IN MICROWAVE DATA EARLIER TODAY...
BECAME APPARENT IN GEOSTATIONARY SATELLITE IMAGES A FEW HOURS AGO.
THE OVERALL CLOUD PATTERN IS WELL ORGANIZED WITH COLD CLOUD TOPS
SURROUNDING THE RAGGED EYE AND BANDING FEATURES LOCATED IN ALL
QUADRANTS. SATELLITE INTENSITY ESTIMATES HAVE INCREASED TO 4.0/65
KT FROM TAFB...4.5/77 KT FROM SAB...AND 4.7/82 KT FROM UW-CIMSS.
THE INITIAL WIND SPEED IS SET AT 80 KT...NEAR THE HIGH END OF THE
ESTIMATES GIVEN THE IMPROVED SATELLITE PRESENTATION SINCE THE TIME
OF THE DVORAK CLASSIFICATIONS.

ADDITIONAL STRENGTHENING SEEMS LIKELY DURING THE NEXT DAY OR SO AS
MIRIAM IS EXPECTED TO REMAIN OVER SEA SURFACE TEMPERATURES OF
27-28C AND IN A FAVORABLE UPPER-LEVEL WIND PATTERN. IN 36 TO 48
HOURS...HOWEVER...MIRIAM IS FORECAST TO BE MOVING OVER COOL WATERS
AND IN MODERATE SOUTHWESTERLY WIND SHEAR. THESE UNFAVORABLE
CONDITIONS SHOULD END THE STRENGTHENING TREND...AND CAUSE THE
CYCLONE TO WEAKEN. THE NHC INTENSITY FORECAST IS HIGHER THAN THE
PREVIOUS ONE FOR THE FIRST 36 HOURS AND THEN FALLS IN LINE WITH THE
OLD ONE AFTER THAT.

MIRIAM IS MOVING NORTHWESTWARD AT ABOUT 10 KT. THIS GENERAL HEADING
WITH A SLIGHT REDUCTION IN FORWARD SPEED IS EXPECTED OVER THE NEXT
24 TO 36 HOURS AS THE RIDGE TO THE NORTHEAST OF MIRIAM WEAKENS.
AFTER THAT...A TURN TO THE NORTH AT AN EVEN SLOWER FORWARD SPEED IS
FORECAST AS THE HURRICANE MOVES INTO A WEAKNESS CAUSED BY A TROUGH
OVER THE WESTERN UNITED STATES. THE NHC TRACK FORECAST IS BASICALLY
AN UPDATE OF THE PREVIOUS ONE...AND REMAINS NEAR THE RIGHT SIDE OF
THE GUIDANCE ENVELOPE BETWEEN THE CONSENSUS AIDS TO THE WEST AND
THE GFS AND ECMWF MODELS TO THE EAST.

FORECAST POSITIONS AND MAX WINDS

INIT 24/0300Z 16.8N 111.3W 80 KT 90 MPH
12H 24/1200Z 17.6N 112.5W 95 KT 110 MPH
24H 25/0000Z 18.5N 113.9W 95 KT 110 MPH
36H 25/1200Z 19.2N 114.8W 90 KT 105 MPH
48H 26/0000Z 19.8N 115.2W 80 KT 90 MPH
72H 27/0000Z 21.2N 115.9W 60 KT 70 MPH
96H 28/0000Z 22.5N 116.0W 45 KT 50 MPH
120H 29/0000Z 24.0N 115.5W 30 KT 35 MPH

$$
FORECASTER CANGIALOSI
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#82 Postby Yellow Evan » Sun Sep 23, 2012 9:56 pm

Woah, 80 knts? That was unexpected? Yet, NHC still thinking it will peak at Cat 2 :S
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Re: EPAC: MIRIAM - Hurricane

#83 Postby euro6208 » Sun Sep 23, 2012 11:02 pm

hopefully this will dissipate over water and affect no one...
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#84 Postby Kingarabian » Mon Sep 24, 2012 1:50 am

EP, 13, 2012092406, , BEST, 0, 170N, 1117W, 90, 971, HU, 64, NEQ, 25, 20, 15, 20, 1009, 250, 10, 0, 0, E, 0, , 0, 0, MIRIAM, D,
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#85 Postby Kingarabian » Mon Sep 24, 2012 3:19 am

Probably a MH already.

Image

Image

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 24 SEP 2012 Time : 073000 UTC
Lat : 17:03:58 N Lon : 111:51:10 W


CI# /Pressure/ Vmax
5.6 / 957.5mb/104.6kt


Final T# Adj T# Raw T#
5.6 6.0 6.0
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#86 Postby Kingarabian » Mon Sep 24, 2012 3:51 am

000
WTPZ43 KNHC 240847
TCDEP3

HURRICANE MIRIAM DISCUSSION NUMBER 10
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
200 AM PDT MON SEP 24 2012

MIRIAM HAS CONTINUED TO RAPIDLY STRENGTHEN. A SMALL 10 N MI DIAMETER
COULD-FILLED EYE IS EMBEDDED IN THE NORTHWEST QUADRANT OF A COLD
CENTRAL DENSE OVERCAST FEATURE THAT HAS BECOME MORE CIRCULAR OVER
THE PAST FEW HOURS. SATELLITE INTENSITY ESTIMATES ARE A CONSENSUS
T5.0/90 KT FROM TAFB AND SAB...AND THE LATEST UW-CIMSS ESTIMATE IS
T5.6/105 KT. BASED ON THESE DATA...THE INITIAL INTENSITY HAS BEEN
INCREASED TO 90 KT...WHICH COULD BE ON THE CONSERVATIVE SIDE.

THE INITIAL MOTION ESTIMATE 305/11 KT. MIRIAM IS BASICALLY ON
TRACK...SO THERE IS NO CHANGE TO THE PREVIOUS FORECAST TRACK
THROUGH 36 HOURS. AFTER THAT...HOWEVER...THE TRACK HAS BEEN SHIFTED
TO THE EAST OF AND A LITTLE FASTER THAN THE PREVIOUS ADVISORY DUE
TO MIRIAM FORECAST TO BE A DEEPER AND MORE ROBUST CYCLONE SIMILAR
TO WHAT THE GFS AND ECMWF MODELS ARE INDICATING. THE UKMET MODEL
WAS COMPLETELY DISCOUNTED SINCE IT WAS WAS POORLY INITIALIZED AND
IS ONLY FORECASTING A VERY WEAK AND SHALLOW CYCLONE THAT DISSIPATES
AND MOVES SLOWLY NORTHWEST AND WESTWARD WITH TIME...WHICH HAS
RESULTED IN A DEGRADATION OF THE CONSENSUS MODELS TV15 AND TVCE. A
BROAD MID-LEVEL TROUGH CURRENTLY ALONG THE U.S. WEST COAST IS
FORECAST TO SLOWLY AMPLIFY SOUTHWARD OFF THE COAST OF BAJA
CALIFORNIA AND CREATE A LARGE BREAK IN THE SUBTROPICAL RIDGE TO THE
NORTH OF THE CYCLONE BY 48 HOURS. THIS CHANGING FLOW PATTERN IS
EXPECTED TO GRADUALLY TURN MIRIAM NORTHWARD BY 72 HOURS...AND THEN
RECURVE THE SYSTEM SLOWLY TO THE NORTHEAST TOWARD BAJA CALIFORNIA
ON DAYS 4 AND 5. GIVEN THE PERSISTENT WEST BIAS OF THE UKMET...
GFDL...AND HWRF MODELS...THE OFFICIAL FORECAST IS SIMILAR TO BUT
SLOWER THAN A BLEND OF THE GFS...GFS-ENSEMBLE MEAN...AND ECMWF
FORECAST TRACKS.

GIVEN THE SMALL-DIAMETER EYE AND LOW SHEAR EXPECTED FOR THE NEXT 12
HOURS OR SO...ADDITIONAL RAPID STRENGTHENING INTO A MAJOR HURRICANE
SEEMS HIGHLY PLAUSIBLE. IT IS POSSIBLE THAT MIRIAM COULD EVEN REACH
CATEGORY 4 INTENSITY...BUT THE RATHER SMALL EYE COULD NEGATE THAT
POSSIBILITY DUE TO A PROBABLE EYEWALL REPLACEMENT CYCLE SOMETIME
DURING THE NEXT 24 HOURS. BY 36 HOURS AND BEYOND...MODERATE
SOUTHWESTERLY SHEAR AHEAD OF THE AFOREMENTIONED MID-/UPPER-LEVEL
TROUGH IS EXPECTED TO INDUCE GRADUAL WEAKENING. HOWEVER...THE
WEAKENING TREND IS NOT EXPECTED TO BE AS FAST AS INDICATED IN
PREVIOUS ADVISORIES NOW THAT MIRIAM IS FORECAST TO BE FARTHER EAST
AND...THEREFORE...OVER WARMER SSTS. THE NHC INTENSITY FORECAST IS
ABOVE ALL OF THE GUIDANCE FOR THE NEXT 24 HOURS...AND THEN FOLLOWS
THE INTENSITY CONSENSUS MODELS TV15 AND IVCN.

FORECAST POSITIONS AND MAX WINDS

INIT 24/0900Z 17.3N 112.2W 90 KT 105 MPH
12H 24/1800Z 18.0N 113.2W 105 KT 120 MPH
24H 25/0600Z 18.8N 114.3W 110 KT 125 MPH
36H 25/1800Z 19.6N 114.8W 100 KT 115 MPH
48H 26/0600Z 20.4N 115.2W 90 KT 105 MPH
72H 27/0600Z 22.2N 115.5W 75 KT 85 MPH
96H 28/0600Z 24.0N 115.5W 60 KT 70 MPH
120H 29/0600Z 25.5N 114.5W 50 KT 60 MPH

$$
FORECASTER STEWART

Love Stewart's disco's...
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Re: EPAC: MIRIAM - Hurricane

#87 Postby Chickenzilla » Mon Sep 24, 2012 6:53 am

I think the structure of Hurricane Miriam does not look very good on this microwave image by TMI that is less than 6 hours old.
I don't see any inner eyewall and an outer eyewall seems to be forming.
I may be wrong so please correct me if I am wrong.

Image

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#88 Postby brunota2003 » Mon Sep 24, 2012 7:02 am

I think the inner eyewall is that L shape in the middle. I'm not sure if the eye is just too small to pick up at that resolution? It does seem like an outer eyewall is forming, though.
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#89 Postby Yellow Evan » Mon Sep 24, 2012 7:48 am

Anyone here think this system will be upped to a major soon?
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Re: EPAC: MIRIAM - Hurricane

#90 Postby euro6208 » Mon Sep 24, 2012 10:44 am

Now Major Hurricane Miriam!



000
WTPZ43 KNHC 241450
TCDEP3

HURRICANE MIRIAM DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
800 AM PDT MON SEP 24 2012

THE RAPID INTENSIFICATION PHASE THAT MIRIAM HAS BEEN UNDERGOING
CONTINUES. THE HURRICANE HAS MAINTAINED A COMPACT AND FAIRLY
SYMMETRIC CENTRAL DENSE OVERCAST WITH VERY COLD CLOUD TOP
TEMPERATURES DURING THE PAST SEVERAL HOURS. A PINHOLE EYE...EVIDENT
IN FIRST-LIGHT VISIBLE IMAGERY...HAS ALSO BEEN WARMING. A 0829 UTC
TRMM PASS SUGGESTED THAT AN OUTER EYEWALL COULD BE FORMING AT A
LARGE RADIUS...BUT THERE ARE NO SIGNS OF IT CONTRACTING. DVORAK
T-NUMBERS ARE 5.5 AND 5.0 FROM SAB AND TAFB...RESPECTIVELY...AND THE
LATEST ADT CI VALUES ARE 5.8. A BLEND OF THESE DATA YIELD AN
INITIAL INTENSITY ESTIMATE OF 105 KT.

THE EYE OF MIRIAM HAS BEEN WOBBLING DURING THE PAST SEVERAL HOURS.
SMOOTHING THROUGH THESE WOBBLES GIVES AN INITIAL MOTION ESTIMATE OF
OF 305/10. MIRIAM IS ABOUT TO MOVE AROUND WESTERN EDGE OF A MID-
LEVEL RIDGE OVER NORTHERN MEXICO AND INTO A WEAKNESS ALONG 115W.
THIS SYNOPTIC PATTERN SHOULD RESULT IN A GRADUAL NORTHWARD TURN AND
A REDUCTION IN FORWARD SPEED DURING THE NEXT FEW DAYS. AS A MID-/
UPPER-LEVEL CYCLONE FORMS OFFSHORE OF THE SOUTHERN CALIFORNA COAST
ON DAYS 4-5 AND SLIDES EASTWARD...MIRIAM SHOULD BE PUSHED NORTH-
NORTHEASTWARD OR EVEN NORTHEASTWARD. THE NHC TRACK FORECAST IS
LARGELY UNCHANGED RELATIVE TO THE PREVIOUS ONE. THE FORECAST
REMAINS ON THE RIGHT SIDE OF THE GUIDANCE ENVELOPE...HEAVILY
WEIGHTED TOWARD THE GFS/ECMWF.

BARRING AN EYEWALL REPLACEMENT...MIRIAM COULD STILL INTENSIFY A
BIT MORE DURING THE NEXT 12-24 HOURS IN A LOW SHEAR ENVIRONMENT AND
OVER WARM WATERS. A GRADUAL DECAY IS LIKELY FROM 24-48 HOURS AS
MIRIAM MOVES OVER MARGINALLY WARM WATERS...FOLLOWED BY A STEADIER
DECLINE AFTER THAT AS MIRIAM ENCOUNTERS AN INCREASE IN UPPER-LEVEL
WESTERLY FLOW. BY DAYS 4-5...A FURTHER INCREASE IN WESTERLY SHEAR
IS EXPECTED AS MIRIAM INTERACTS WITH THE CLOSED LOW TO ITS WEST.
THIS SHOULD LEAD TO A MORE RAPID WEAKENING AND PERHAPS A DECOUPLING
OF THE CYCLONE...AS DEPICTED IN THE ECWMF. ALTHOUGH THE NHC
INTENSITY FORECAST IS GENERALLY ABOVE THE GUIDANCE...IT IS LOWER
COMPARED TO THE PREVIOUS ADVISORY FROM DAYS 3-5.


FORECAST POSITIONS AND MAX WINDS

INIT 24/1500Z 17.7N 112.9W 105 KT 120 MPH
12H 25/0000Z 18.4N 113.8W 110 KT 125 MPH
24H 25/1200Z 19.1N 114.6W 105 KT 120 MPH
36H 26/0000Z 19.9N 114.9W 95 KT 110 MPH
48H 26/1200Z 20.9N 115.1W 85 KT 100 MPH
72H 27/1200Z 22.8N 115.3W 65 KT 75 MPH
96H 28/1200Z 24.8N 114.8W 50 KT 60 MPH
120H 29/1200Z 26.1N 113.7W 35 KT 40 MPH

$$
FORECASTER KIMBERLAIN
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Re: EPAC: MIRIAM - Hurricane

#91 Postby euro6208 » Mon Sep 24, 2012 10:46 am

Image

pinhole eye!

looks like many of our typhoons over here....
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#92 Postby Ntxw » Mon Sep 24, 2012 10:52 am

Even though the past few haven't in this basin, lets hope she goes for what the basin is known for the past several years, "go big or go home!" (In open waters of course)

Image
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Re: EPAC: MIRIAM - Hurricane

#93 Postby cycloneye » Mon Sep 24, 2012 1:30 pm

18z Best Track

EP, 13, 2012092418, , BEST, 0, 178N, 1132W, 105, 958, HU
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#94 Postby brunota2003 » Mon Sep 24, 2012 2:42 pm

Looks like Miriam may have peaked. Eyewall is weakening on the Northern side and starting to open up. I don't think it is an EWC, either.
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Re: EPAC: MIRIAM - Hurricane

#95 Postby cycloneye » Mon Sep 24, 2012 3:42 pm

HURRICANE MIRIAM DISCUSSION NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
200 PM PDT MON SEP 24 2012

THE INTENSIFICATION PHASE THAT MIRIAM HAS BEEN UNDERGOING HAS COME
TO AN END...AS THERE HAS BEEN A DEGRADATION IN THE SATELLITE
APPEARANCE OF THE CYCLONE IN THE LAST FEW HOURS. CLOUD TOP
TEMPERATURES HAVE GRADUALLY BEEN WARMING AND THE EYE HAS BECOME
LESS DISTINCT. A 1640 UTC TRMM IMAGE INDICATED THAT AN EYEWALL
REPLACEMENT COULD BE UNDERWAY...WITH A SMALL INNER EYEWALL EVIDENT
AND AN OUTER EYEWALL HAVING CONTRACTED SLIGHTLY TO A RADIUS OF 50 N
MI. DVORAK T-NUMBERS HAVE LEVELED OFF AT 5.5 FROM BOTH SATELLITE
AGENCIES...AND UW-CIMSS ADT CI VALUES HAVE DECREASED TO 5.6. THE
INITIAL INTENSITY ESTIMATE IS HELD AT 105 KT...IN AGREEMENT WITH
THESE DATA.

THE EYE OF MIRIAM HAS WOBBLED A BIT TO THE LEFT DURING THE LAST FEW
HOURS...AND HAS SLOWED IN FORWARD SPEED. A LONGER-TERM AVERAGE OF
CENTER FIXES GIVES AN INITIAL MOTION ESTIMATE OF 305/08. MIRIAM
SHOULD CONTINUE ON A SLOWER NORTHWESTWARD COURSE FOR THE NEXT DAY
OR SO AS IT ROUNDS THE SOUTHWESTERN SIDE OF A MID-LEVEL RIDGE OVER
NORTHERN MEXICO. AFTER THAT TIME...MIRIAM SHOULD MOVE INTO A
WEAKNESS ALONG 115W AND TURN NORTHWARD FOR A COUPLE OF DAYS. THE
INFLUENCE OF A MID- TO UPPER-LEVEL LOW FORMING OFFSHORE OF THE
SOUTHERN CALIFORNIA COAST FROM DAYS 3-5 SHOULD PUSH THE TRACK OF
MIRIAM NORTH-NORTHEASTWARD...OR EVEN NORTHEASTWARD...DURING THAT
TIME. NO SUBSTANTIVE CHANGES WERE MADE TO THE PREVIOUS
FORECAST...WHICH IS WEIGHTED HEAVILY ON A BLEND OF THE ECMWF AND
GFS MODELS. AS IN PREVIOUS OFFICIAL FORECASTS...THIS IS NEAR THE
RIGHT SIDE OF THE GUIDANCE ENVELOPE.

IT IS UNCLEAR AS TO WHETHER THE CURRENT EYEWALL REPLACEMENT WILL
CONTINUE. IN ANY EVENT...A COMPLETION OF THE EYEWALL REPLACEMENT
CYCLE IS NOT LIKELY TO OCCUR BEFORE MIRIAM REACHES MARGINALLY WARM
WATERS AND SOME INCREASE IN WESTERLY SHEAR IN ABOUT 24 HOURS.
WEAKENING IS EXPECTED DURING THE INTERIM AND AFTERWARDS AS THE
CYCLONE MOVES CLOSE TO A STRONG GRADIENT OF SSTS AND EXPERIENCES
MODERATE WESTERLY SHEAR. A FURTHER INCREASE IN WESTERLY SHEAR
ASSOCIATED THE ABOVEMENTIONED CLOSED MID- TO UPPER-LEVEL CYCLONE TO
THE WEST OF MIRIAM WILL LIKELY OCCUR LATE IN THE PERIOD. THERE IS
NOW A GENERAL AGREEMENT OF BOTH THE ECWMF AND GFS GUIDANCE THAT
THIS WILL RESULT IN A DECOUPLING OF THE CYCLONE AND A RAPID
WEAKENING. THE NHC INTENSITY FORECAST HAS BEEN REDUCED RELATIVE TO
THE PREVIOUS ONE...REPRESENTING AN AVERAGE OF THE SHIPS/LGEM AND
THE LATEST INTENSITY CONSENSUS AIDS. REMNANT LOW STATUS IN
INDICATED ON DAY 5.

FORECAST POSITIONS AND MAX WINDS

INIT 24/2100Z 18.1N 113.5W 105 KT 120 MPH
12H 25/0600Z 18.5N 114.2W 100 KT 115 MPH
24H 25/1800Z 19.3N 114.8W 90 KT 105 MPH
36H 26/0600Z 20.1N 115.0W 80 KT 90 MPH
48H 26/1800Z 21.1N 115.1W 70 KT 80 MPH
72H 27/1800Z 23.4N 115.2W 55 KT 65 MPH
96H 28/1800Z 25.5N 114.4W 40 KT 45 MPH
120H 29/1800Z 27.5N 113.5W 30 KT 35 MPH

$$
FORECASTER KIMBERLAIN
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Re: EPAC: MIRIAM - Hurricane

#96 Postby Yellow Evan » Mon Sep 24, 2012 4:12 pm

euro6208 wrote:Image

pinhole eye!

looks like many of our typhoons over here....


You said the magic word.
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Re: EPAC: MIRIAM - Hurricane

#97 Postby cycloneye » Mon Sep 24, 2012 7:39 pm

00z Best Track shows the downward trend starting.


EP, 13, 2012092500, , BEST, 0, 183N, 1137W, 90, 968, HU

ftp://ftp.nhc.noaa.gov/atcf/tcweb/inves ... 012.invest
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Re: EPAC: MIRIAM - Hurricane

#98 Postby cycloneye » Mon Sep 24, 2012 9:42 pm

BULLETIN
HURRICANE MIRIAM ADVISORY NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
800 PM PDT MON SEP 24 2012

...MIRIAM BEGINS TO WEAKEN...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...18.5N 113.9W
ABOUT 400 MI...640 KM SW OF THE SOUTHERN TIP OF BAJA CALIFORNIA
MAXIMUM SUSTAINED WINDS...105 MPH...165 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...968 MB...28.59 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 800 PM PDT...0300 UTC...THE CENTER OF HURRICANE MIRIAM WAS
LOCATED NEAR LATITUDE 18.5 NORTH...LONGITUDE 113.9 WEST. MIRIAM IS
MOVING TOWARD THE NORTHWEST NEAR 8 MPH...13 KM/H. A GRADUAL TURN TO
THE NORTH WITH A DECREASE IN FORWARD SPEED IS EXPECTED DURING THE
NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 105 MPH...165
KM/H...WITH HIGHER GUSTS. MIRIAM IS A CATEGORY TWO HURRICANE ON
THE SAFFIR-SIMPSON HURRICANE WIND SCALE. SLOW WEAKENING IS
EXPECTED DURING THE NEXT 48 HOURS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 35 MILES...55 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 125
MILES...205 KM. AN AUTOMATED OBSERVING SITE ON CLARION ISLAND
RECENTLY REPORTED A SUSTAINED WIND OF 48 MPH...78 KM/H...AND A GUST
OF 67 MPH...107 KM/H.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 968 MB...28.59 INCHES.


HAZARDS AFFECTING LAND
----------------------
SURF...SWELLS GENERATED BY MIRIAM WILL AFFECT THE SOUTH AND WEST
COASTS OF THE SOUTHERN BAJA PENINSULA DURING THE NEXT COUPLE OF
DAYS. THESE SWELLS ARE LIKELY TO CAUSE LIFE-THREATENING SURF AND
RIP CURRENT CONDITIONS. PLEASE CONSULT PRODUCTS FROM YOUR LOCAL
WEATHER OFFICE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...200 AM PDT.

$$
FORECASTER CANGIALOSI


HURRICANE MIRIAM DISCUSSION NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
800 PM PDT MON SEP 24 2012

MIRIAM HAS WEAKENED OVER THE LAST SEVERAL HOURS. THE EYE HAS BECOME
OVERCAST AND CLOUD TOPS HAVE WARMED NEAR THE CENTER RECENTLY.
MICROWAVE IMAGES INDICATE THAT THE INNER EYEWALL...WHICH WAS
EVIDENT IN A TRMM PASS AROUND 17Z...HAS COLLAPSED. IN ADDITION...
THE LATEST SSMI OVERPASS SHOWED AN ASYMMETRIC STRUCTURE...WHICH IS
LIKELY THE RESULT OF SOUTHWESTERLY SHEAR. SATELLITE INTENSITY
ESTIMATES HAVE DECREASED THIS CYCLE...AND THE INITIAL WIND SPEED IS
LOWERED TO 90 KT BASED ON A BLEND OF THE DVORAK T- AND CI-NUMBERS
FROM TAFB...SAB...AND UW-CIMSS.

A GRADUAL WEAKENING IS FORECAST DURING THE NEXT 24 TO 36 HOURS AS
SOUTHWESTERLY SHEAR...ASSOCIATED WITH A TROUGH TO THE
NORTH-NORTHWEST OF MIRIAM...INCREASES A LITTLE. LATER IN THE
WEEK...THE GLOBAL MODELS SHOW A LARGE MID- TO UPPER-LEVEL LOW
DEVELOPING NEAR 30N 130W. THIS LOW WILL CAUSE A FURTHER INCREASE IN
SOUTHWESTERLY SHEAR. IN FACT...VERTICAL CROSS SECTIONS FROM THE GFS
AND ECMWF GLOBAL MODELS SHOW A TITLED VORTEX THAT IS BEING AFFECTED
BY A DEEP LAYER OF DRY AIR AND WESTERLY FLOW IN 4 TO 5 DAYS. THE
OFFICIAL FORECAST IS A LITTLE LOWER THAN THE PREVIOUS ONE...BUT
SLIGHTLY ABOVE THE CONSENSUS AIDS.

MIRIAM CONTINUES MOVING NORTHWESTWARD BUT AT A SLIGHTLY SLOWER
FORWARD SPEED. A GRADUAL TURN TO THE NORTH IS EXPECTED DURING THE
NEXT 48 TO 72 HOURS AS MIRIAM MOVES TOWARD A TROUGH OVER THE
WESTERN UNITED STATES. BEYOND THAT TIME...A NORTH-NORTHEASTWARD
MOTION IS FORECAST AS MIRIAM BECOMES EMBEDDED IN THE FLOW TO THE
EAST OF THE AFOREMENTIONED MID- TO UPPER-LEVEL LOW. THE OFFICIAL
TRACK FORECAST IS FAIRLY CLOSE TO THE PREVIOUS ONE AND REMAINS
BETWEEN THE GFS AND ECMWF MODELS.

FORECAST POSITIONS AND MAX WINDS

INIT 25/0300Z 18.5N 113.9W 90 KT 105 MPH
12H 25/1200Z 19.0N 114.5W 85 KT 100 MPH
24H 26/0000Z 19.8N 114.9W 80 KT 90 MPH
36H 26/1200Z 20.7N 115.1W 75 KT 85 MPH
48H 27/0000Z 21.8N 115.2W 65 KT 75 MPH
72H 28/0000Z 23.7N 115.4W 50 KT 60 MPH
96H 29/0000Z 25.5N 115.0W 40 KT 45 MPH
120H 30/0000Z 27.0N 114.5W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
FORECASTER CANGIALOSI
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#99 Postby Kingarabian » Mon Sep 24, 2012 11:59 pm

brunota2003 wrote:Looks like Miriam may have peaked. Eyewall is weakening on the Northern side and starting to open up. I don't think it is an EWC, either.

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EWRC almost complete.. Let's see if she can finish it off.
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#100 Postby Kingarabian » Tue Sep 25, 2012 4:22 am

000
WTPZ43 KNHC 250843
TCDEP3

HURRICANE MIRIAM DISCUSSION NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
200 AM PDT TUE SEP 25 2012

MICROWAVE AND INFRARED SATELLITE IMAGERY INDICATE MIRIAM HAS
COMPLETED ITS EYEWALL REPLACEMENT CYCLE AND A 30 N MI DIAMETER EYE
APPEARS TO HAVE STABILIZED. CLOUD TOPS HAVE COOLED SIGNIFICANTLY
AROUND THE EYE OVER THE PAST 4 HOURS...AND UW-CIMSS ADT AND NHC
AODT SATELLITE INTENSITY ESTIMATES HAVE INCREASED TO T5.3/97 KT AND
T5.6/105 KT...RESPECTIVELY. AS A RESULT...THE INITIAL INTENSITY IS
BEING MAINTAINED AT 90 KT...WHICH COULD BE CONSERVATIVE.

THE INITIAL MOTION ESTIMATE IS 310/05 KT. MIRIAM IS ON TRACK AND...
AS A RESULT...THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS
FORECAST TRACK OR REASONING. MIRIAM IS EXPECTED TO GRADUALLY TURN
TOWARD THE NORTHWEST LATER TODAY AND TURN NORTHWARD IN 24-36 HOURS
AS THE CYCLONE BECOMES EMBEDDED IN WEAK SOUTHERLY STEERING FLOW
BETWEEN A SUBTROPICAL RIDGE SITUATED TO THE EAST AND A MID- TO
UPPER-LEVEL LOW LOCATED TO ITS WEST AND NORTHWEST. THE UKMET MODEL
REMAINS A SIGNIFICANT OUTLIER WITH A STRONG WEST BIAS AND HAS...
THEREFORE...BEEN DISCOUNTED FOR THIS FORECAST CYCLE. AS A RESULT...
THE OFFICIAL FORECAST TRACK REMAINS TO THE EAST OF THE CONSENSUS
MODELS TV15 AND TVCE...AND IS FAIRLY CLOSE TO A BLEND OF THE GFS
AND ECMWF MODELS...WHICH BETTER DEPICT A STRONGER AND MORE
VERTICALLY DEEP CYCLONE AS CURRENTLY ANALYZED.

GRADUAL WEAKENING IS FORECAST DURING THE NEXT 24 TO 36 HOURS AS
SOUTHWESTERLY SHEAR INCREASES AHEAD OF A SLOWLY ADVANCING
MID-/UPPER-LEVEL TROUGH NOTED TO THE WEST AND NORTHWEST OF MIRIAM
IN WATER VAPOR IMAGERY. BY DAYS 3-5...THE GLOBAL MODELS ARE
FORECASTING A LARGE MID-/UPPER-LEVEL LOW DEVELOPING NEAR 30N 130W.
THIS LOW IS EXPECTED TO INCREASE THE VERTICAL SHEAR ABOVE 30 KT...
WHICH SHOULD INDUCE MORE RAPID WEAKENING AND POSSIBLE DISSIPATION
BEFORE MIRIAM REACHES BAJA CALIFORNIA. THE OFFICIAL FORECAST IS
SIMILAR TO THE PREVIOUS ADVISORY AND FOLLOWS A BLEND OF THE SHIPS
AND LGEM MODELS.

FORECAST POSITIONS AND MAX WINDS

INIT 25/0900Z 18.7N 114.3W 90 KT 105 MPH
12H 25/1800Z 19.3N 114.7W 85 KT 100 MPH
24H 26/0600Z 20.1N 115.0W 80 KT 90 MPH
36H 26/1800Z 21.1N 115.2W 70 KT 80 MPH
48H 27/0600Z 22.1N 115.3W 65 KT 75 MPH
72H 28/0600Z 24.0N 115.3W 50 KT 60 MPH
96H 29/0600Z 25.7N 114.9W 40 KT 45 MPH
120H 30/0600Z 27.2N 114.4W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
FORECASTER STEWART
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