Wet and windy subtropical storm possible for Southeast U.S.; Mexico eyes TD-10E

By: Dr. Jeff Masters , 3:15 PM GMT on October 06, 2011

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A large low pressure system with heavy rain is expected to develop over Cuba and South Florida on Saturday. The counter-clockwise flow around this low will bring strong winds and heavy rains to much of the Florida coast on Saturday, and these conditions will spread northwards to Georgia by Sunday and South Carolina by Monday. The storm may evolve into a subtropical storm that gets a name by Monday or Tuesday, but the potential location of such a storm is still murky. The extended forecast discussion from NOAA's Hydrometeorological Prediction Center favors a more westerly location, in the eastern Gulf of Mexico, as predicted by the ECMWF model. The GFS model, which puts the storm's center east of Florida, is pushing the weather system that will spawn the subtropical storm too fast to the east. In any case, the exact center location of the storm will not matter that much, since this will be a large, diffuse system that will bring strong winds and heavy rains to a large area of the Southeast U.S. coast, regardless of the exact center location. Portions of the coastal waters from Southeast Louisiana to the Florida Panhandle, as well as from Northeast Florida to South Carolina, are likely to experience sustained winds of 35 - 45 mph Monday and Tuesday. Since the storm is going to get its start as a cold-cored upper-level low pressure system with some dry air aloft, it will probably start out subtropical, with a large band of heavy rain developing well north of the center. Subtropical storms cannot intensify quickly, due to their lack of an organized inner core, and I'm not concerned at present about this storm potentially becoming a hurricane.


Figure 1. Rainfall forecast for the 5-day period ending at 8 am EDT Tuesday, October 11, 2011. The storm system affecting Florida this weekend is expected to bring up to 7 inches of rain along the coast. Heavy rains associated with a strong trough of low pressure are also expected to dump 4 - 6 inches of rain over drought-stricken areas of Texas, Oklahoma, and Kansas. Image credit: NOAA/HPC.

Philippe becomes a hurricane
After 12 days and 49 advisories, Philippe has finally intensified into hurricane, becoming the fifth hurricane of the 2011 Atlantic hurricane season. The fifth hurricane normally arrives on October 7, so this is a very average season for hurricanes, despite the fact it is already the 7th busiest season since record keeping began in 1851 for number of tropical storms--sixteen. Satellite loops show Philippe is a small hurricane with just a hint of an eye. A wide band of clouds to Philippe's northwest is associated with the trough of low pressure that has recurved Philippe to the northeast. By Friday, the trough will bring very high wind shear of 30 - 50 knots, which should cause rapid weakening. Philippe will not trouble any land areas.


Figure 2. Morning satellite image of Philippe. The band of clouds to the northwest of Philippe is associated with a cold front that has recurved Philippe to the northeast.

A double threat to Mexico's Eastern Pacific coast
In the Eastern Pacific off the coast of Mexico, two new tropical cyclones have formed. The one of greatest concern is Tropical Depression 10-E. TD 10-E is currently headed west-northwest, parallel to the coast, but will turn north and then northeast over the weekend as a strong trough of low pressure dives southward over northern Mexico. The computer models have a fairly wide spread for the track of TD-10E, with the region of coast centered on Puerto Vallarta between Manzanillo and Tuxpan at greatest risk of a strike. TD 10-E is under moderate shear of 10 - 20 knots, and shear is predicted to stay in the low to moderate range for the next five days. Ocean temperatures are warm, 28 - 29°C, but the warm waters do not extend to great depth, limiting TD-10E's potential for rapid intensification. Nonetheless, the GFDL model predicts TD-10E will intensify into a major Category 3 hurricane before landfall on Monday on the Mexican coast, and the HWRF model brings the storm to Category 2 strength. The official NHC forecast is less aggressive, bringing TD-10E to Category 1 strength, but this is conservative, and I put the odds at 30% that the storm will be a Cat 2 or stronger at landfall. One possible impediment to development may be TD-10E's close proximity to Tropical Storm Irwin to the west. Upper-level outflow from Irwin could weaken TD-10E, and the two storms may compete for the same moisture. Regardless of TD-10E's strength at landfall, the storm will bring very heavy rains to the Mexican coast capable of causing dangerous flash floods and mudslides, beginning on Monday.

Once TD-10E has made landfall, Mexico may need to concern itself with Tropical Storm Irwin, which is gathering strength farther to the west. Irwin is also moving to the west-northwest, and will also be turned north and then northeast towards the coast of Mexico this weekend by the same trough of low pressure expected to affect TD 10-E. The longer range computer forecast models show Irwin could make landfall on the Mexican coast late next week.

European heat wave: hottest October temperatures on record for the UK
The British Isles have been basking in an unprecedented October heat wave this week, which has brought the warmest temperature ever measured in the UK for the month of October. On Oct. 1, a reading of 29.9°C (85.8°F) was recorded at Gravesend, Kent, beating the previous UK October record of 29.4°C (84.9°F) at Cambridgeshire on Oct. 1, 1985. Wales also broke their warmest temperature for October with a 28.2°C (82.7°F) at Hawarden, Flintshire. Edinburgh, Scotland reached 24.7°C (76.4°F) for Scotland's warmest temperature in at least 50 years. Thanks go to wunderground's weather historian Christopher C. Burt. His latest post is on record hurricanes of the past in the Pacific Ocean.

Jeff Masters

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509. dfwstormwatch
2:27 PM GMT on October 07, 2011
i will continue on the new blog...
Link
Member Since: July 31, 2011 Posts: 4 Comments: 753
508. TropicalAnalystwx13
2:25 PM GMT on October 07, 2011
NEW BLOG!
Member Since: July 6, 2010 Posts: 109 Comments: 30263
507. dfwstormwatch
2:24 PM GMT on October 07, 2011

51 hours out... the low reforms farther west just south of the Florida keys
Member Since: July 31, 2011 Posts: 4 Comments: 753
506. JNCali
2:23 PM GMT on October 07, 2011
Quoting TropicalAnalystwx13:

Unless I'm here and you're over there, which happens to be the case (:

I'm still over <------------ here
Member Since: September 9, 2010 Posts: 5 Comments: 1032
505. dfwstormwatch
2:22 PM GMT on October 07, 2011
Quoting TropicalAnalystwx13:

lol, it was there at 39 hours.

aww i missed that...
Member Since: July 31, 2011 Posts: 4 Comments: 753
504. dfwstormwatch
2:21 PM GMT on October 07, 2011

12z nam 45 hours out... 1008 MB low heading north towards the Miami area...
Member Since: July 31, 2011 Posts: 4 Comments: 753
503. TropicalAnalystwx13
2:20 PM GMT on October 07, 2011
Quoting dfwstormwatch:

success! we get a low pressure system @ 42 hours out...

lol, it was there at 39 hours.
Member Since: July 6, 2010 Posts: 109 Comments: 30263
502. dfwstormwatch
2:18 PM GMT on October 07, 2011

success! we get a low pressure system @ 42 hours out...
Member Since: July 31, 2011 Posts: 4 Comments: 753
501. aspectre
2:17 PM GMT on October 07, 2011
29.3n57.1w has been re-evaluated&altered for H.Phillipe's_7Oct_12pmGMT_ATCF
29.3n57.4w, 29.8n56.2w are now the most recent positions
Starting 6Oct_12pmGMT and ending 7Oct_12pmGMT

The 4 western line-segments represent HurricanePhillippe's path,
the easternmost line-segment is the straightline projection for 7Oct_12pmGMT,
the coastline blob at 33.75n7.31w-CAS is the endpoint of the straightline projection
connected to its nearest airport for the 7Oct_6amGMT*mapping,
and the island blob at 38.565n28.779w-HOR is the same for the 7Oct_12amGMT.

Using straightline projection of the travel-speed&heading derived from the
ATCF coordinates spanning the 6hours between 6amGMT then 12pmGMT :
H.Phillipe's travel-speed was 13.3mph(21.5k/h) on a heading of 64.2degrees(ENE)
H.Phillipe was headed toward passing 5.5miles(8.9kilometres) south of SaoMiguel,Azores ~5days15hours from now

Copy&paste 38.565n28.779w-hor, 33.75n7.31w-cas, 27.4n60.4w-28.3n59.7w, 28.3n59.7w-28.8n58.7w, 28.8n58.7w-29.3n57.4w, 29.3n57.4w-29.8n56.2w, 29.3n57.4w-37.626n25.51w, pdl into the GreatCircleMapper for more info

The previous mapping for 7Oct_6amGMT
Member Since: August 21, 2007 Posts: 0 Comments: 4860
500. dfwstormwatch
2:13 PM GMT on October 07, 2011

12z nam 39 hours out says... no low forming Saturday...
Member Since: July 31, 2011 Posts: 4 Comments: 753
499. TropicalAnalystwx13
2:13 PM GMT on October 07, 2011
Quoting aspectre:
No, I'm here. You are over there.

Unless I'm here and you're over there, which happens to be the case (:
Member Since: July 6, 2010 Posts: 109 Comments: 30263
498. aspectre
2:09 PM GMT on October 07, 2011
495 TropicalAnalystwx13 "I'm here..."

No, I am here. You are over there.
Member Since: August 21, 2007 Posts: 0 Comments: 4860
497. TropicalAnalystwx13
2:09 PM GMT on October 07, 2011
Quoting dfwstormwatch:

here's the nam's 30 hour rainfall forecast so far...

Rain totals will really ramp up as we head into Sunday and Monday across the state of Florida.

By the beginning of next week, a lot of the southeast will experience heavy rain. Lets hope it rains itself out before getting to the Northeast.
Member Since: July 6, 2010 Posts: 109 Comments: 30263
496. dfwstormwatch
2:08 PM GMT on October 07, 2011

here's the nam's 30 hour rainfall forecast so far...
Member Since: July 31, 2011 Posts: 4 Comments: 753
495. TropicalAnalystwx13
2:07 PM GMT on October 07, 2011
Quoting dfwstormwatch:
where'd every1 go?

I'm here..
Member Since: July 6, 2010 Posts: 109 Comments: 30263
494. dfwstormwatch
2:06 PM GMT on October 07, 2011
where'd every1 go?
Member Since: July 31, 2011 Posts: 4 Comments: 753
493. dfwstormwatch
2:04 PM GMT on October 07, 2011

12z nam 27 hours out
Member Since: July 31, 2011 Posts: 4 Comments: 753
492. dfwstormwatch
2:01 PM GMT on October 07, 2011
\
12z nam 24 hours out
Member Since: July 31, 2011 Posts: 4 Comments: 753
491. dfwstormwatch
1:58 PM GMT on October 07, 2011

12z nam 18 hours out
Member Since: July 31, 2011 Posts: 4 Comments: 753
490. dfwstormwatch
1:56 PM GMT on October 07, 2011

12z nam 15 hours out, still no low yet
Member Since: July 31, 2011 Posts: 4 Comments: 753
489. hydrus
1:56 PM GMT on October 07, 2011
Mexico may be hit with two storms in the same area..Link
Member Since: September 27, 2007 Posts: 1 Comments: 19558
488. will40
1:56 PM GMT on October 07, 2011
Quoting hydrus:
It is the last system that has the potential to be the most dangerous..If that position and path were to pan out, a powerful storm could enter the gulf.


the second low on the 06z Gfs is showing that also
Member Since: September 19, 2005 Posts: 2 Comments: 4066
487. Chucktown
1:55 PM GMT on October 07, 2011
If you take a look at the water vapor, you can plainly see the positively tilted trough over the eastern Gulf. The surface reflection of the impending low will probably set up somewhere along the west coast of Florida, maybe near the Keys, then lift north to northeast throughout the weekend. Regardless if this becomes sub-tropical or not, it is going to produce a solid shield of moderate to occasionally heavy rain. Almost like an overunning situation. Either way, this is a good chance for Florida and much of the SE US coast to get a soaking rainfall. The most serious threat will be the tightened gradient that sets up over NE coastal Florida on up through eastern NC. There may be some beach erosion from the prolonged strong NE fetch and I wouldn't rule out a few "spin ups" northeast of wherever the center of this low pressure sets up as helicity values rise. Its just not going to have enough time over water to become fully warm core or deepen all that much. With all that being said, this is looking more and more like a nor'easter, only in the south, so I guess we can call it a sou'easter.

Link
Member Since: August 27, 2006 Posts: 0 Comments: 1663
486. hydrus
1:53 PM GMT on October 07, 2011
Quoting whepton3:


I think we're about to get multiple systems in short order...

You're on the money about the CMC maybe having a new idea.
It is the last system that has the potential to be the most dangerous..If that position and path were to pan out, a powerful storm could enter the gulf.
Member Since: September 27, 2007 Posts: 1 Comments: 19558
485. dfwstormwatch
1:52 PM GMT on October 07, 2011

12z nam 12 hours out
Member Since: July 31, 2011 Posts: 4 Comments: 753
484. whepton3
1:52 PM GMT on October 07, 2011
Quoting hydrus:
The NOGAPS is interesting this morning. It might actually do pretty good this time since the predicted system should not become fully tropical..Link


NOGAPS is also biting on that low that CMC is presenting S. of Cuba later next week in that last frame.
Member Since: July 19, 2010 Posts: 0 Comments: 645
483. CitikatzSouthFL
1:51 PM GMT on October 07, 2011
Quoting hydrus:
This mornings CMC run is rather unsettling...Hope this links,Link


EEK!
Member Since: August 14, 2009 Posts: 0 Comments: 414
482. TampaFLUSA
1:49 PM GMT on October 07, 2011
Whatever it will be, the weather won't be strongest near the center. Most of the time subtropical systems have their worst weather far from the center, especially in this instance with the strong high ne of the center.
Member Since: June 21, 2007 Posts: 10 Comments: 1657
481. dfwstormwatch
1:49 PM GMT on October 07, 2011

12z nam 9 hours out
Member Since: July 31, 2011 Posts: 4 Comments: 753
480. hydrus
1:49 PM GMT on October 07, 2011
Member Since: September 27, 2007 Posts: 1 Comments: 19558
479. marknmelb
1:48 PM GMT on October 07, 2011
Hopefully we get some rain here in Melbourne. We're almost a foot short for the year. Noting compared to Texas but we still need some rain here.
Member Since: July 17, 2006 Posts: 0 Comments: 406
478. hydrus
1:47 PM GMT on October 07, 2011
The NOGAPS is interesting this morning. It might actually do pretty good this time since the predicted system should not become fully tropical..Link
Member Since: September 27, 2007 Posts: 1 Comments: 19558
477. dfwstormwatch
1:46 PM GMT on October 07, 2011

12z nam 6 hours out
Member Since: July 31, 2011 Posts: 4 Comments: 753
476. AussieStorm
1:41 PM GMT on October 07, 2011
Quoting FLGatorCaneNut:


It's rain, not snow.....

A rear wheel drive car can be fun in the rain, as long as you know how to control it.
Member Since: September 30, 2007 Posts: 9 Comments: 15749
475. JNCali
1:41 PM GMT on October 07, 2011
SoCal Record Report (Too early in the year for me)
Statement as of 6:30 PM PDT on October 6, 2011


... Lowest maximum temperature records broken or tied on October 6...

Location new record old record period of record

El Cajon 67 69 in 2010 since 1979
Escondido 66 69 in 2010 since 1979
Laguna Beach 62 67 in 1935 since 1928
Newport Beach 64 66 in 2001 since 1921
Palm Springs 76 tied 76 in 2010 since 1906
thermal 79 tied 79 in 1977 since 1950
Vista 67 68 in 2009 since 1957
Member Since: September 9, 2010 Posts: 5 Comments: 1032
474. TropicalAnalystwx13
1:41 PM GMT on October 07, 2011
Quoting KUEFC:
Its not "definate" at all, its a forecast, and forecasts can be wrong, and you cant have a "subtropical" low pressure system, a low pressure system is a low pressure system, the effects arent the same at all, a subtropical storm would bring near tropical storm force winds to florida, while a low pressure system will bring winds of 20 - 25mph, trust me we have them all the time in the UK, just yesterday infact.

And that makes all the difference..

Florida will receive several inches of rain, with winds near tropical storm strength. Go read the NWS discussions, you will see that a SUBTROPICAL low pressure area is expected to develop over the weekend.
Member Since: July 6, 2010 Posts: 109 Comments: 30263
473. dfwstormwatch
1:39 PM GMT on October 07, 2011
Link
nothing impressive on the tropical Atlantic false color rgb loop... except for Phillipe which is of no concern...
Member Since: July 31, 2011 Posts: 4 Comments: 753
472. whepton3
1:38 PM GMT on October 07, 2011
Quoting hydrus:
This mornings CMC run is rather unsettling...Hope this links,Link


I think we're about to get multiple systems in short order...

You're on the money about the CMC maybe having a new idea.
Member Since: July 19, 2010 Posts: 0 Comments: 645
471. hydrus
1:37 PM GMT on October 07, 2011
S.P.C 3 day..DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT FRI OCT 07 2011

VALID 091200Z - 101200Z

...SYNOPSIS...

WRN U.S. CUTOFF LOW WILL TRANSITION TO AN OPEN WAVE AND FINALLY
EJECT NEWD THROUGH THE PLAINS AS A STRONG JET MAX APPROACHES THE
PACIFIC NW. MODEL CONSENSUS IS THAT ONE VORT MAX WILL LIFT THROUGH
THE NRN PLAINS WITH A WEAKER IMPULSE ADVANCING THROUGH THE BASE OF
THE TROUGH INTO THE SRN PLAINS. A WEAK SURFACE LOW WILL DEVELOP
ALONG QUASI-STATIONARY FRONT AND LIFT NWD INTO NEB AND THE DAKOTAS
IN ASSOCIATION WITH EJECTING NRN IMPULSE. THE FRONT WILL EXTEND FROM
THE UPPER MS VALLEY SWWD THROUGH THE CNTRL AND SRN PLAINS EARLY
SUNDAY AND IS EXPECTED TO MOVE VERY LITTLE DURING THE DAY. MEANWHILE
AN AREA OF LOW PRESSURE IS FORECAST TO EVOLVE OVER THE SERN GULF OF
MEXICO AND WILL LIKELY AFFECT A PORTION OF THE FL PENINSULA.

...SRN FL...

STRENGTHENING LOW LEVEL WINDS BETWEEN ERN U.S. HIGH PRESSURE AND THE
DEVELOPING AREA OF LOW PRESSURE OVER THE ERN GULF WILL LIKELY
CONTRIBUTE TO A ZONE OF ENHANCED LOW LEVEL SHEAR OVER A PORTION OF
THE FL PENINSULA. AS THE LOW DEVELOPS NWWD...RICHER BOUNDARY LAYER
MOISTURE WILL ADVECT INLAND CONTRIBUTING TO POTENTIAL FOR SLIGHTLY
GREATER INSTABILITY ACROSS SRN FL. HOWEVER...EXPECTED WIDESPREAD
CLOUDS AND PRECIPITATION SHOULD RESULT IN MARGINAL INSTABILITY AND
WEAK LAPSE RATES. AS A RESULT...OVERALL SEVERE THREAT DOES NOT
WARRANT MORE THAN 5% SEVERE PROBABILITIES AT THIS TIME.
Member Since: September 27, 2007 Posts: 1 Comments: 19558
470. KUEFC
1:37 PM GMT on October 07, 2011
Quoting TropicalAnalystwx13:

Its definite that a Subtropical low will form over the weekend. It is not definite whether or not it strengthens into a Subtropical storm.

Regardless, the effects will be the same.
Its not "definate" at all, its a forecast, and forecasts can be wrong, and you cant have a "subtropical" low pressure system, a low pressure system is a low pressure system, the effects arent the same at all, a subtropical storm would bring near tropical storm force winds to florida, while a low pressure system will bring winds of 20 - 25mph, trust me we have them all the time in the UK, just yesterday infact.
Member Since: October 9, 2008 Posts: 0 Comments: 93
469. whepton3
1:36 PM GMT on October 07, 2011
Quoting Seflhurricane:
looking at satelite images we need to watch closely around andros island in the bahamas , looks like something may be trying to get going there tomorrow morning will be intresting


Methinks it could be a good bit west of there.
Near the coast of NW Cuba.

Coin toss.
Member Since: July 19, 2010 Posts: 0 Comments: 645
468. TropicalAnalystwx13
1:35 PM GMT on October 07, 2011
Latest CIMSS ADT T#'s:

Philippe:

CI# /Pressure/ Vmax
4.8 / 968.7mb/ 84.8kt

Irwin:

CI# /Pressure/ Vmax
4.7 / 977.5mb/ 82.2kt

Jova:

CI# /Pressure/ Vmax
3.9 / 990.1mb/ 63.0kt
Member Since: July 6, 2010 Posts: 109 Comments: 30263
467. whepton3
1:35 PM GMT on October 07, 2011
Quoting hydrus:
This mornings CMC run is rather unsettling...Hope this links,Link


Looks like three different systems for Florida to me.

This weekend, then another Tues-Wed...

and then at the end of the run there's something getting together south of Cuba.

Link worked fine, but the scenario works badly.

That. Would. Not. Be. Good.
Member Since: July 19, 2010 Posts: 0 Comments: 645
466. hydrus
1:35 PM GMT on October 07, 2011
This has a gulf low in four days...
Member Since: September 27, 2007 Posts: 1 Comments: 19558
465. dfwstormwatch
1:34 PM GMT on October 07, 2011

heres the 12z surface analysis just releases! no tropical low yet, but the cold fronts entering Texas prepare for heavy rainfall!
Member Since: July 31, 2011 Posts: 4 Comments: 753
464. WeatherfanPR
1:29 PM GMT on October 07, 2011
Quoting dfwstormwatch:

its not expected to form till tomorrow or Sunday, the subtropical storm will form from the low sometime next week.



I'm hoping nothing develop
Member Since: August 23, 2006 Posts: 0 Comments: 1563
463. FLGatorCaneNut
1:27 PM GMT on October 07, 2011
Quoting starbuck02:
I have to drive from Jacksonville to Cape Coral today and back on Monday. Should be a fun drive with my rear wheel car lol.


It's rain, not snow.....
Member Since: July 26, 2009 Posts: 0 Comments: 178
462. dfwstormwatch
1:27 PM GMT on October 07, 2011
Quoting KUEFC:
There is only the gfs even hints at sub trop storm, but yet people acting like its definate

so does the euro,the cmc, the nam,and pretty much 75% of all the other models...
Member Since: July 31, 2011 Posts: 4 Comments: 753
461. Vero1
1:27 PM GMT on October 07, 2011
72 Hrs.

Member Since: July 21, 2008 Posts: 4 Comments: 2233
460. TropicalAnalystwx13
1:26 PM GMT on October 07, 2011
Quoting KUEFC:
There is only the gfs even hints at sub trop storm, but yet people acting like its definate

Its definite that a Subtropical low will form over the weekend. It is not definite whether or not it strengthens into a Subtropical storm.

Regardless, the effects will be the same.
Member Since: July 6, 2010 Posts: 109 Comments: 30263
459. KUEFC
1:24 PM GMT on October 07, 2011
There is only the gfs even hints at sub trop storm, but yet people acting like its definate
Member Since: October 9, 2008 Posts: 0 Comments: 93

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.