EPAC: MIRIAM - Post-Tropical

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#101 Postby Yellow Evan » Tue Sep 25, 2012 7:40 am

Won't be surprised to see to re-intensification today.
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#102 Postby Hurricane_Luis » Tue Sep 25, 2012 10:46 am

Defiantly weakening

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Re: EPAC: MIRIAM - Hurricane

#103 Postby cycloneye » Tue Sep 25, 2012 3:47 pm

HURRICANE MIRIAM DISCUSSION NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
200 PM PDT TUE SEP 25 2012

THE CLOUD PATTERN OF MIRIAM HAS DETERIORATED SIGNIFICANTLY DURING
THE PAST FEW HOURS. THE COVERAGE AND INTENSITY OF DEEP CONVECTION
HAS BEEN DECREASING...WHILE THE CENTRAL FEATURES OF THE CYCLONE
HAVE BECOME LESS DISTINCT. UPPER-LEVEL WESTERLY FLOW ASSOCIATED
WITH A DEVELOPING MID- TO UPPER-LEVEL LOW SEEN IN WATER VAPOR
IMAGERY NEAR 26N111W IS ALREADY IMPINGING ON MIRIAM...WITH SHIPS
AND UW-CIMSS SHEAR ANALYSES CURRENTLY DIAGNOSING 20 KT OF
SOUTHWESTERLY SHEAR. DVORAK T-NUMBERS ARE AT 4.0 AND 4.5 FROM SAB
AND TAFB...WHILE ADT CI VALUES ARE RUNNING A BIT HIGHER. THE
INITIAL INTENSITY ESTIMATE IS LOWERED TO 75 KT IN AGREEMENT WITH
THESE DATA.

THE ABOVEMENTIONED UPPER-LEVEL TROUGH APPROACHING MIRIAM WILL
PRODUCE PERSISTENT MODERATE TO STRONG SOUTHWESTERLY SHEAR OVER THE
CYCLONE AS IT MOVES OVER GRADUALLY DECREASING SSTS. AS A RESULT...
STEADY WEAKENING IS EXPECTED DURING THE NEXT 48 HOURS. AS THE SHEAR
BECOMES MORE EXTREME BY DAY 3...THE GFS AND ECMWF DEPICT MIRIAM
DECOUPLING AND LIKELY DISSIPATING BY DAY 5. THE NHC INTENSITY
FORECAST IS REDUCED AGAIN COMPARED TO THE PREVIOUS ONE IN BEST
AGREEMENT WITH THE SHIPS AND LGEM OUTPUT. GIVEN THE GOOD MODEL
AGREEMENT...REMNANT LOW STATUS IS NOW INDICATED SOONER...ON DAY 3.

THE INITIAL MOTION ESTIMATE IS 300/04. MIRIAM IS ABOUT TO TURN
TOWARD THE NORTHWEST AROUND THE WESTERN EDGE OF A MID-LEVEL RIDGE
EXTENDING FROM THE GULF OF MEXICO. A SLOW NORTH-NORTHWESTWARD
MOTION SHOULD COMMENCE BY TOMORROW AND CONTINUE FOR THE NEXT COUPLE
OF DAYS AS THE CYCLONE MOVES INTO A WEAKNESS ALONG 115W. THE MODEL
GUIDANCE HAS SHIFTED WESTWARD THIS CYCLE IN THE SHORT TERM...
PARTIALLY IN RESPONSE TO THE MORE WESTERLY INITIAL MOTION THAT HAS
PERSISTED LONGER THAN EXPECTED. SINCE IT APPEARS THAT MIRIAM WILL
BECOME A SHALLOW VORTEX SOONER THAN PREVIOUSLY EXPECTED...THE NHC
TRACK HAS BEEN SHIFTED SOMEWHAT TO THE WEST OF THE PREVIOUS ONE.

FORECAST POSITIONS AND MAX WINDS

INIT 25/2100Z 18.9N 114.9W 75 KT 85 MPH
12H 26/0600Z 19.6N 115.1W 65 KT 75 MPH
24H 26/1800Z 20.7N 115.4W 55 KT 65 MPH
36H 27/0600Z 21.9N 115.8W 45 KT 50 MPH
48H 27/1800Z 23.0N 116.0W 40 KT 45 MPH
72H 28/1800Z 24.2N 116.1W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 29/1800Z 25.5N 116.1W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 30/1800Z...DISSIPATED

$$
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Re: EPAC: MIRIAM - Hurricane

#104 Postby cycloneye » Tue Sep 25, 2012 9:58 pm

HURRICANE MIRIAM DISCUSSION NUMBER 17
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
800 PM PDT TUE SEP 25 2012

MODERATE SOUTHWESTERLY VERTICAL SHEAR IS CONTINUING TO TAKE ITS TOLL
ON MIRIAM THIS EVENING. THE CONVECTION IS LOSING ITS CENTRAL DENSE
OVERCAST AND BEGINNING TO SHOW MORE OF A SHEAR PATTERN. DVORAK
CURRENT INTENSITY ESTIMATES ARE AT 77 KT FROM TAFB AND 65 KT FROM
SAB WHILE A 2214Z AMSU INTENSITY ESTIMATE FROM CIMSS WAS 72 KT. A
BLEND OF THESE GIVES 70 KT AT THE ADVISORY TIME.

TWO FORTUITOUS AMSU AND SSMIS MICROWAVE PASSES PROVIDE A RELATIVELY
CONFIDENT ESTIMATE THAT THE MOTION OF MIRIAM IS NEAR 310/4. THE
CYCLONE IS CURRENTLY BEING STEERED PRIMARILY BY THE INFLUENCE OF A
WEAK DEEP-LAYER RIDGE TO ITS EAST. A CONTINUED SLOW MOVEMENT TOWARD
THE NORTH-NORTHWEST OR NORTH IS EXPECTED FOR THE NEXT TWO DAYS. AS
THE SYSTEM TRANSFORMS INTO A REMNANT LOW...IT SHOULD TURN TOWARD
THE NORTHWEST WHILE BEING ADVECTED ALONG IN THE LOW-LEVEL FLOW. THE
TRACK PREDICTION IS SLIGHTLY SLOWER AND A BIT TO THE WEST OF THE
PREVIOUS ADVISORY. THE NEW FORECAST IS ALSO CLOSE TO THE TRACK
CONSENSUS EXCLUDING THE UKMET...AS THIS MODEL HAS AN
UNREALISTICALLY SLOW SPEED IN COMPARISON TO ALL OF THE REMAINING
GUIDANCE.

MIRIAM SHOULD CONTINUE TO GRADUALLY WEAKEN UNDER THE COMBINED
INFLUENCE OF MODERATE VERTICAL SHEAR...COOLING SSTS AND A MORE
STABLE ATMOSPHERE. THE CYCLONE SHOULD BECOME A REMNANT LOW AROUND
THREE DAYS AS THE SSTS BY THAT TIME SHOULD BE AROUND 24C. THE
INTENSITY PREDICTION IS CLOSEST TO THE LGEM AND SHIPS STATISTICAL
MODELS AND IS VERY SIMILAR TO THAT OF THE PREVIOUS ADVISORY.


FORECAST POSITIONS AND MAX WINDS

INIT 26/0300Z 19.1N 115.2W 70 KT 80 MPH
12H 26/1200Z 19.8N 115.6W 60 KT 70 MPH
24H 27/0000Z 21.0N 115.7W 50 KT 60 MPH
36H 27/1200Z 22.2N 116.2W 40 KT 45 MPH
48H 28/0000Z 22.9N 116.5W 35 KT 40 MPH
72H 29/0000Z 23.5N 117.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 30/0000Z 24.0N 117.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 01/0000Z...DISSIPATED

$$
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Re: EPAC: MIRIAM - Tropical Storm

#105 Postby cycloneye » Wed Sep 26, 2012 5:24 am

TROPICAL STORM MIRIAM DISCUSSION NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
200 AM PDT WED SEP 26 2012

THE CONVECTIVE ORGANIZATION OF MIRIAM HAS GONE RAPIDLY DOWNHILL OVER
THE PAST SEVERAL HOURS WITH MOST OF THE SIGNIFICANT THUNDERSTORM
ACTIVITY NORTH OF THE CENTER. THE CENTRAL DENSE OVERCAST HAS ALSO
BECOME RATHER ELONGATED...AND AN EARLIER EYE FEATURE IS NO LONGER
APPARENT ON MICROWAVE DATA. SATELLITE INTENSITY ESTIMATES RANGE
FROM 55-72 KT...AND GIVEN THE POOR SATELLITE APPEARANCE...THE
INITIAL WIND SPEED IS LOWERED TO 60 KT. CONTINUED WEAKENING IS
LIKELY DUE TO MODERATE OR STRONG SOUTHWESTERLY SHEAR...GRADUALLY
COOLING SSTS...AND ENTRAINMENT OF A MORE STABLE AIRMASS. THE NEW
FORECAST IS CLOSE TO A BLEND OF THE PREVIOUS ONE AND THE INTENSITY
CONSENSUS.

AN UNCERTAIN INITIAL MOTION ESTIMATE IS 320/5. ALMOST ALL THE
GUIDANCE MOVE MIRIAM TO THE NORTH OR NORTH-NORTHWEST TODAY IN
RESPONSE TO A DIGGING TROUGH SEEN ALONG 120W IN WATER VAPOR IMAGES.
AS THE TROUGH DROPS SOUTH OF THE TROPICAL CYCLONE IN A DAY OR
TWO...MIRIAN WILL PROBABLY TURN TO THE NORTHWEST. THE OFFICIAL
FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ONE...CLOSE TO THE
FSU SUPERENSEMBLE...THROUGH 48 HOURS. AFTER THAT TIME...LITTLE
MOTION IS INDICATED AS THE WEAK REMNANT SYSTEM WILL BE POSITIONED
IN LIGHT STEERING CURRENTS.


FORECAST POSITIONS AND MAX WINDS

INIT 26/0900Z 19.5N 115.5W 60 KT 70 MPH
12H 26/1800Z 20.3N 115.7W 50 KT 60 MPH
24H 27/0600Z 21.5N 116.0W 45 KT 50 MPH
36H 27/1800Z 22.4N 116.4W 35 KT 40 MPH
48H 28/0600Z 22.9N 116.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 29/0600Z 23.2N 116.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 30/0600Z 23.5N 117.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 01/0600Z...DISSIPATED

$$
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#106 Postby Yellow Evan » Wed Sep 26, 2012 7:37 am

Miriam weakening in a heartbeat
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Re: EPAC: MIRIAM - Tropical Storm

#107 Postby cycloneye » Wed Sep 26, 2012 9:54 am

TROPICAL STORM MIRIAM DISCUSSION NUMBER 19
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
800 AM PDT WED SEP 26 2012

THE CLOUD PATTERN OF MIRIAM HAS BECOME POORLY ORGANIZED. THE CENTRAL
DENSE OVERCAST HAS DEGENERATED INTO A LONG BAND WRAPPING AROUND THE
WESTERN SIDE OF THE CIRCULATION. SATELLITE DATA ALSO INDICATE AN
INCREASING SEPARATION BETWEEN THE LOW- TO MID-LEVEL CENTERS DUE TO
20-25 KT OF SOUTHWESTERLY SHEAR ASSOCIATED WITH A SHORTWAVE TROUGH
ROTATING AROUND THE NORTHWESTERN SIDE OF THE STORM. SATELLITE
INTENSITY ESTIMATES RANGE FROM 55-65 KT...AND GIVEN THE
DETERIORATING SATELLITE APPEARANCE...THE INITIAL INTENSITY IS
LOWERED TO 55 KT. FURTHER GRADUAL WEAKENING IS LIKELY AS MIRIAM
ENCOUNTERS CONTINUED MODERATE OR STRONG SOUTHWESTERLY SHEAR...
GRADUALLY DECREASING SSTS...AND A DRIER AND MORE STABLE AIR MASS.
THE NHC INTENSITY FORECAST IS AN UPDATE OF THE PREVIOUS ONE AND IS
CLOSE TO THE SHIPS AND LGEM OUTPUT.

THE LONG-TERM INITIAL MOTION ESTIMATE IS 330/05...BUT RECENT
MICROWAVE DATA SUGGEST THAT THE SHORT-TERM MOTION COULD BE FARTHER
TO THE RIGHT. AS THE PREVIOUSLY MENTIONED SHORTWAVE TROUGH DIGS TO
THE WEST OF MIRIAM DURING THE NEXT DAY OR SO...THE CYCLONE SHOULD
MAINTAIN A SLOW NORTH-NORTHWESTWARD MOTION. A BEND OF THE TRACK
TOWARD THE NORTHWEST IS FORECAST WHEN THE SHORTWAVE REACHES A
POSITION TO THE SOUTH OF STORM IN 24-36 HOURS. IF MIRIAM DECOUPLES
SOONER THAN EXPECTED...THE LOW-LEVEL CENTER COULD MOVE MORE TO THE
LEFT THAN FORECAST. THE NHC TRACK FORECAST IS NEAR OR SLIGHTLY TO
THE LEFT OF THE PREVIOUS ONE AND IS CLOSE TO THE FSU
SUPERENSENSEMBLE AND THE MULTI-MODEL CONSENSUS THROUGH 24 HOURS AND
THEN CLOSE TO THE GFS AFTER THAT.


FORECAST POSITIONS AND MAX WINDS

INIT 26/1500Z 20.0N 115.7W 55 KT 65 MPH
12H 27/0000Z 20.9N 115.9W 45 KT 50 MPH
24H 27/1200Z 22.0N 116.3W 40 KT 45 MPH
36H 28/0000Z 22.6N 116.7W 35 KT 40 MPH
48H 28/1200Z 23.0N 117.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 29/1200Z 23.2N 117.4W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 30/1200Z 23.4N 117.9W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 01/1200Z...DISSIPATED

$$
FORECASTER KIMBERLAIN
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#108 Postby Chickenzilla » Wed Sep 26, 2012 10:18 am

Weakening...

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#109 Postby Cyclenall » Wed Sep 26, 2012 12:45 pm

This became a major hurricane on a day I didn't even check the tropics once. I only thought it would reach CAT1 strength but it found a nice spot. After the outrageously long time without a decent storm, when the Epac put out it ended up lasting only 12 hours at 105 knots, like Michael from the Atlantic :roll: . Whoop de doo.

Looks like Miriam is weakening very fast now.
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Re: EPAC: MIRIAM - Tropical Storm

#110 Postby cycloneye » Wed Sep 26, 2012 3:37 pm

TROPICAL STORM MIRIAM DISCUSSION NUMBER 20
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
200 PM PDT WED SEP 26 2012

SATELLITE IMAGES INDICATE THAT MIRIAM CONTINUES TO WEAKEN...AS THE
20-25 KT OF SOUTHWESTERLY SHEAR DIAGNOSED OVER THE CYCLONE IS
GRADUALLY TAKING A TOLL. INNER CORE CONVECTION IS MINIMAL...AND
DEEP CONVECTION IN A BAND WRAPPING AROUND THE PERIPHERY OF THE
CIRCULATION HAS WARMED CONSIDERABLY DURING THE PAST SEVERAL HOURS.
DVORAK T-NUMBERS ARE SLOWLY DECREASING...AND A BLEND OF T-
AND CI-NUMBERS IS USED TO ARRIVE AT THE INITIAL INTENSITY ESTIMATE
OF 50 KT.

NO DECREASE IN THE SOUTHWESTERLY TO WEST-SOUTHWESTERLY SHEAR IS
PREDICTED DURING THE NEXT COUPLE OF DAYS. THE COMBINATION OF THE
SHEAR...PROGRESSIVELY COOLER WATERS...AND THE ENTRAINMENT OF A
SUBSTANTIALLY DRIER AND MORE STABLE AIR MASS SHOULD PROMOTE
ADDITIONAL WEAKENING. THE NHC INTENSITY FORECAST IS JUST ABOUT THE
SAME AS THE PREVIOUS ONE...AND IS LINE WITH THE SHIPS...LGEM...
AND INTENSITY CONSENSUS AIDS. REMNANT LOW STATUS IS INDICATED IN 48
HOURS...THOUGH IT COULD OCCUR SOONER.

MICROWAVE DATA AND VISIBLE SATELLITE IMAGERY WERE USED TO MAKE AN
EASTWARD RELOCATION OF THE CENTER....AND HAVE BEEN HELPFUL IN
ESTABLISHING A MORE CONFIDENT INITIAL MOTION OF 350/06. SO LONG AS
AS THE CIRCULATION OF MIRIAM MAINTAINS VERTICAL INTEGRITY...THE
CYCLONE SHOULD MOVE CYCLONICALLY AROUND A PIECE OF AN UPPER-LEVEL
TROUGH CURRENTLY ROTATING AROUND THE STORM. AS THE CYCLONE BECOMES
MORE SHALLOW IN NATURE AND RESPONDS TO THE LOW- LEVEL FLOW...A
WESTWARD BEND IS ANTICIPATED. THIS BEND COULD EVEN BE TOWARD THE
SOUTHWEST OR SOUTH-SOUTHWEST...AS DEPICTED IN SEVERAL MODEL
SOLUTIONS. THE NHC TRACK IS ADJUSTED SLIGHTLY TO THE LEFT AFTER 24
HOURS...NEAR BUT TO THE NORTH OF THE MULTI-MODEL CONSENSUS.


FORECAST POSITIONS AND MAX WINDS

INIT 26/2100Z 20.8N 115.4W 50 KT 60 MPH
12H 27/0600Z 21.6N 115.6W 45 KT 50 MPH
24H 27/1800Z 22.4N 116.1W 35 KT 40 MPH
36H 28/0600Z 22.8N 116.5W 30 KT 35 MPH
48H 28/1800Z 22.9N 116.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 29/1800Z 22.9N 117.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 30/1800Z 22.9N 117.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 01/1800Z...DISSIPATED

$$
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#111 Postby Hurricane_Luis » Wed Sep 26, 2012 5:05 pm

Latest loop

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Re: EPAC: MIRIAM - Tropical Storm

#112 Postby cycloneye » Wed Sep 26, 2012 9:35 pm

TROPICAL STORM MIRIAM DISCUSSION NUMBER 21
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
800 PM PDT WED SEP 26 2012

CONVECTIVE CLOUD TOPS CONTINUE TO WARM...AND DEEP CONVECTION IS
LIMITED TO A BAND LOCATED ABOUT 150 N MI TO THE NORTH OF THE
CENTER. DVORAK NUMBERS HAVE DROPPED TO T3.0/4.0 FROM TAFB AND
T2.0/3.0 FROM SAB. BASED ON A BLEND OF THE FINAL-T AND CI
NUMBERS...THE ADVISORY INTENSITY IS SET AT 40 KT. THIS IS
SUPPORTED BY A CI NUMBER OF 2.8 FROM THE LATEST UW-CIMSS ADT
ESTIMATE.

MIRIAM WILL CONTINUE TO BE AFFECTED BY 20-25 KT OF DEEP-LAYER
WEST-SOUTHWESTERLY SHEAR IN THE COMING DAYS...AND THE CENTER IS
BEGINNING TO MOVE OVER WATER THAT IS COLDER THAN 26C. THIS
ENVIRONMENT IS NOT LIKELY TO SUPPORT SIGNIFICANT DEEP CONVECTION...
AND MIRIAM COULD BECOME POST-TROPICAL AS EARLY AS THURSDAY IF
CURRENT CONVECTIVE TRENDS HOLD. THE NHC INTENSITY FORECAST FOLLOWS
THE SAME WEAKENING SHOWN BY THE STATISTICAL GUIDANCE...AND MOST OF
THE GLOBAL MODELS DISSIPATE THE REMNANT LOW IN ABOUT 5 DAYS.

MIRIAM IS MOVING NORTH-NORTHWESTWARD AT ABOUT 6 KT AS IT ROTATES
AROUND A MID-TROPOSPHERIC LOW LOCATED NOT TOO FAR TO ITS WEST. THE
CYCLONE WILL SOON BE RUNNING INTO A LARGE AREA OF HIGH PRESSURE
CENTERED TO THE WEST OF CALIFORNIA...AND IT IS LIKELY TO BEGIN
MOVING SLOWLY WESTWARD OR EVEN SOUTHWESTWARD AFTER 48 HOURS.
ALMOST ALL THE TRACK MODELS SHOW THE HIGH PRESSURE PUSHING MIRIAM
SOUTHWARD BEFORE IT DISSIPATES...AND THAT SCENARIO IS INDICATED IN
THE OFFICIAL FORECAST.

FORECAST POSITIONS AND MAX WINDS

INIT 27/0300Z 21.5N 115.7W 40 KT 45 MPH
12H 27/1200Z 22.2N 116.1W 35 KT 40 MPH
24H 28/0000Z 22.7N 116.6W 30 KT 35 MPH
36H 28/1200Z 22.8N 117.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 29/0000Z 22.9N 117.3W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 30/0000Z 22.9N 117.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/0000Z 22.5N 118.0W 15 KT 15 MPH...POST-TROP/REMNT LOW
120H 02/0000Z...DISSIPATED

$$
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Re: EPAC: MIRIAM - Tropical Storm

#113 Postby cycloneye » Thu Sep 27, 2012 5:17 am

TROPICAL STORM MIRIAM DISCUSSION NUMBER 22
NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012
200 AM PDT THU SEP 27 2012

MIRIAM IS BARELY HOLDING ON AS A TROPICAL CYCLONE...WITH ANY DEEP
CONVECTION LOCATED BETWEEN 75 AND 105 N MI N OF THE CENTER.
ALTHOUGH THE LATEST SUBJECTIVE DVORAK ESTIMATES ARE LOWER THAN
EARLIER...AN ASCAT PASS AT 0440 UTC HAD WINDS STILL HAD WINDS OF
ABOUT 40 KT. IN CONSIDERATION OF THE LOW BIAS OF THAT SATELLITE...
THE INITIAL WIND SPEED IS KEPT AT 40 KT. WEAKENING IS FORECAST BY
ALL GUIDANCE DUE TO MODERATE OR STRONG SHEAR AND COOL SSTS. THE
OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS ONE...BUT IT SHOWS
MIRIAM BECOMING A REMNANT LOW WITHIN 24 HOURS. IF CURRENT
CONVECTIVE TRENDS CONTINUE...IT COULD BE SOONER THAN THAT TIME.

RECENT INFRARED IMAGES SHOW THAT MIRIAM IS MOVING AT ABOUT 330/5.
THE STORM SHOULD SLOW DOWN AND TURN WESTWARD AND SOUTHWARD WITH
TIME AS BECOMES STEERED BY THE EASTERN PACIFIC SUBTROPICAL HIGH.
THE OFFICIAL FORECAST IS A BIT SOUTH OF THE PREVIOUS ONE...BUT NOT
AS FAR SOUTH AS THE LATEST GFS/ECMWF GUIDANCE.


FORECAST POSITIONS AND MAX WINDS

INIT 27/0900Z 21.8N 116.0W 40 KT 45 MPH
12H 27/1800Z 22.3N 116.5W 35 KT 40 MPH
24H 28/0600Z 22.5N 116.9W 30 KT 35 MPH...POST-TROP/REMNT LOW
36H 28/1800Z 22.5N 117.3W 25 KT 30 MPH...POST-TROP/REMNT LOW
48H 29/0600Z 22.4N 117.6W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 30/0600Z 22.0N 118.0W 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 01/0600Z...DISSIPATED

$$
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Re: EPAC: MIRIAM - Tropical Storm

#114 Postby downsouthman1 » Thu Sep 27, 2012 9:02 am

Everything I'm about to post is my opinion. So take from it what you will. But in reviewing water vapor loops, it appears to me that Miriam is in a bubble, traveling NE. I don't see how it's going to change direction about 180 degrees. The flow of the ULL west of CA should pull the Miriam Nwd, where it should get picked up by the ULL over CO before it transitions into an Ely moving wave. Based on what I see, I believe Miriam will continue on it's current NEly/ENEly jog.
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Re: EPAC: MIRIAM - Tropical Storm

#115 Postby brunota2003 » Thu Sep 27, 2012 10:09 am

downsouthman1 wrote:Everything I'm about to post is my opinion. So take from it what you will. But in reviewing water vapor loops, it appears to me that Miriam is in a bubble, traveling NE. I don't see how it's going to change direction about 180 degrees. The flow of the ULL west of CA should pull the Miriam Nwd, where it should get picked up by the ULL over CO before it transitions into an Ely moving wave. Based on what I see, I believe Miriam will continue on it's current NEly/ENEly jog.

With all of the convection stripped away, Miriam will not be influenced by upper level winds (which is what you see on water vapor, hence why you can really see the ULL). It'll follow the low level winds.
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Re: EPAC: MIRIAM - Tropical Storm

#116 Postby downsouthman1 » Thu Sep 27, 2012 10:10 am

brunota2003 wrote:
downsouthman1 wrote:Everything I'm about to post is my opinion. So take from it what you will. But in reviewing water vapor loops, it appears to me that Miriam is in a bubble, traveling NE. I don't see how it's going to change direction about 180 degrees. The flow of the ULL west of CA should pull the Miriam Nwd, where it should get picked up by the ULL over CO before it transitions into an Ely moving wave. Based on what I see, I believe Miriam will continue on it's current NEly/ENEly jog.

With all of the convection stripped away, Miriam will not be influenced by upper level winds (which is what you see on water vapor, hence why you can really see the ULL). It'll follow the low level winds.

So, in other words, what I'm watching is mid & UL moisture, not the low-level low itself?
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Re: EPAC: MIRIAM - Tropical Storm

#117 Postby brunota2003 » Thu Sep 27, 2012 10:17 am

downsouthman1 wrote:
brunota2003 wrote:
downsouthman1 wrote:Everything I'm about to post is my opinion. So take from it what you will. But in reviewing water vapor loops, it appears to me that Miriam is in a bubble, traveling NE. I don't see how it's going to change direction about 180 degrees. The flow of the ULL west of CA should pull the Miriam Nwd, where it should get picked up by the ULL over CO before it transitions into an Ely moving wave. Based on what I see, I believe Miriam will continue on it's current NEly/ENEly jog.

With all of the convection stripped away, Miriam will not be influenced by upper level winds (which is what you see on water vapor, hence why you can really see the ULL). It'll follow the low level winds.

So, in other words, what I'm watching is mid & UL moisture, not the low-level low itself?

Correct. That is why the cyclone, among other things, is weakening. At the upper levels, the winds are blowing toward the NE, and stripping the remaining convection off in that direction (along with the mid/upper level circulation)...but the low level low itself will not follow that after they completely separate.

So, in a sense, you are correct in that the moisture will be stripped away in that direction, but the LLC will not. As a matter of fact, if you look at the IR loop ( http://www.ssd.noaa.gov/PS/TROP/floater ... imated.gif ), you can see the storms being pulled to the NE, but look closely at the circulation itself. It was drifting north, and it already appears to have stopped and has started a slow westward drift.

I wish I had a link to the charts showing the different flow levels.
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Re: EPAC: MIRIAM - Tropical Storm

#118 Postby downsouthman1 » Thu Sep 27, 2012 10:22 am

brunota2003 wrote:
downsouthman1 wrote:So, in other words, what I'm watching is mid & UL moisture, not the low-level low itself?

Correct. That is why the cyclone, among other things, is weakening. At the upper levels, the winds are blowing toward the NE, and stripping the remaining convection off in that direction (along with the mid/upper level circulation)...but the low level low itself will not follow that after they completely separate.

So, in a sense, you are correct in that the moisture will be stripped away in that direction, but the LLC will not. As a matter of fact, if you look at the IR loop ( http://www.ssd.noaa.gov/PS/TROP/floater ... imated.gif ), you can see the storms being pulled to the NE, but look closely at the circulation itself. It was drifting north, and it already appears to have stopped and has started a slow westward drift.

I wish I had a link to the charts showing the different flow levels.
That is freakin awesome! Thanks for that link. You're totally right; you can actually see the mid & UL moisture being sucked NE while the low-level circulation does, in fact, start moving west in like the last 4 frames.
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Re: EPAC: MIRIAM - Tropical Storm

#119 Postby brunota2003 » Thu Sep 27, 2012 10:45 am

EDIT: I went through and saved the current images and added them below...so anyone can see them for future reference!

downsouthman1 wrote:That is freakin awesome! Thanks for that link. You're totally right; you can actually see the mid & UL moisture being sucked NE while the low-level circulation does, in fact, start moving west in like the last 4 frames. I can't figure out how to fix my post.

It'll be easier to see in visible loops, but right now there are only 3 or 4 frames. If you use the feature called RGB, (Still image: http://www.ssd.noaa.gov/PS/TROP/floater ... 0-lalo.jpg ) they actually take the visible images and the computers color the low level clouds yellow, while everything else stays white. It makes tracking the clouds quite a bit easier, but only really works during the day.

RGB Image:

Image

Miriam Floater links:
http://www.ssd.noaa.gov/PS/TROP/floater ... oater.html

Here are a couple of wind maps:
http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

When you first click on the link, you should see the Upper Level winds (if not, you can click the button at the top that says "Upper Level Winds"). You can see the upper level winds near Miriam are out of the SW/WSW (the levels of these winds are between 500 and 100 millibars, and they are colored coded).

Image

If you click on "Lower Level Winds" (next to the Upper Level button), you can see the LLC of Miriam. Look to the west of that and all across the lower half of the image you can see the winds are generally from the NE/E. That is your lower level flow, and what will steer the LLC of Miriam. In this case, mainly focus on the 800 mb to 950 mb wind barbs (they are green).

Of note: On the lower level map, check out the front over the NE Pacific and strong low over the Gulf of Alaska! Pretty neat feature.

Image

Now, if you look to the right of those two buttons, click on the one labeled "Wind Shear". This is the current diagnosed shear values, based on differences in wind speed and direction over the height of the atmosphere. Miriam is between the 20 knot line and 30 knot line, so wind shear affecting Miriam is roughly 25 knots (give or take). Now, wind shear can and does change rapidly, and the charts aren't always 100% accurate. The key to remember about that chart is that it is not what will happen in the future, it is what is happening NOW.

Image

Click on the button that reads "Shear Tendency". This product shows the current wind shear values (in color...you can see 20 knots is green and 30 knots is yellow, roughly, and Miriam is kind of sitting between the two). It also shows what the shear has done over the past 24 hours. Has it dropped? Increased? Or stayed the same? Mostly over Miriam, it has stayed the same. You can see the legend at the bottom explaining what lines mean what.

Image

Lastly, all of these wind/shear products are not exactly "live". You need to look at the time stamp on the images. In this case, the shear tendency image was created at 1500 UTC (or 11 am EDT) 27 Sept 2012 (today). That means the tendency shown is from 15 UTC yesterday to 15 UTC today!

One last thing:
The images are made about every 3 hours...you can "step backward" in time to view older images if you wish...but they only go back so far (I'm not sure how far though).
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Re: EPAC: MIRIAM - Tropical Storm

#120 Postby downsouthman1 » Thu Sep 27, 2012 11:54 am

brunota2003 wrote:EDIT: I went through and saved the current images and added them below...so anyone can see them for future reference!

downsouthman1 wrote:That is freakin awesome! Thanks for that link. You're totally right; you can actually see the mid & UL moisture being sucked NE while the low-level circulation does, in fact, start moving west in like the last 4 frames. I can't figure out how to fix my post.

It'll be easier to see in visible loops, but right now there are only 3 or 4 frames. If you use the feature called RGB, (Still image: http://www.ssd.noaa.gov/PS/TROP/floater ... 0-lalo.jpg ) they actually take the visible images and the computers color the low level clouds yellow, while everything else stays white. It makes tracking the clouds quite a bit easier, but only really works during the day.

RGB Image:



Miriam Floater links:
http://www.ssd.noaa.gov/PS/TROP/floater ... oater.html

Here are a couple of wind maps:
http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

When you first click on the link, you should see the Upper Level winds (if not, you can click the button at the top that says "Upper Level Winds"). You can see the upper level winds near Miriam are out of the SW/WSW (the levels of these winds are between 500 and 100 millibars, and they are colored coded).



If you click on "Lower Level Winds" (next to the Upper Level button), you can see the LLC of Miriam. Look to the west of that and all across the lower half of the image you can see the winds are generally from the NE/E. That is your lower level flow, and what will steer the LLC of Miriam. In this case, mainly focus on the 800 mb to 950 mb wind barbs (they are green).

Of note: On the lower level map, check out the front over the NE Pacific and strong low over the Gulf of Alaska! Pretty neat feature.



Now, if you look to the right of those two buttons, click on the one labeled "Wind Shear". This is the current diagnosed shear values, based on differences in wind speed and direction over the height of the atmosphere. Miriam is between the 20 knot line and 30 knot line, so wind shear affecting Miriam is roughly 25 knots (give or take). Now, wind shear can and does change rapidly, and the charts aren't always 100% accurate. The key to remember about that chart is that it is not what will happen in the future, it is what is happening NOW.



Click on the button that reads "Shear Tendency". This product shows the current wind shear values (in color...you can see 20 knots is green and 30 knots is yellow, roughly, and Miriam is kind of sitting between the two). It also shows what the shear has done over the past 24 hours. Has it dropped? Increased? Or stayed the same? Mostly over Miriam, it has stayed the same. You can see the legend at the bottom explaining what lines mean what.



Lastly, all of these wind/shear products are not exactly "live". You need to look at the time stamp on the images. In this case, the shear tendency image was created at 1500 UTC (or 11 am EDT) 27 Sept 2012 (today). That means the tendency shown is from 15 UTC yesterday to 15 UTC today!

One last thing:
The images are made about every 3 hours...you can "step backward" in time to view older images if you wish...but they only go back so far (I'm not sure how far though).
Awesome info! I'm a tiny bit confused by the low-level flow though, as tropical systems are lows, which generally suck air in at a somewhat counter-clockwise fashion. Therefore, isn't it not necessarily indicative of where it'll travel? That said & aside from that, I can see fairly neutral LL flow directly around Miriam, but not very far west, a moderate Ely flow at 800-950mb.

And you're right, that certainly is neat watching the flow around that Alaska low with associated cold front.
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