Global model runs discussion

[cycloneye]

GFS continues to show a little more action in the MDR,like CMC has at the same timeframe of 144 hours.



http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

[jconsor]

Looking at the pattern, with the 500 mb Bermuda high forecast to extend west toward the east coast and even into the Gulf of Mexico, the best chances of development over the next 7-10 days look to be from the Bahamas west through the Gulf of Mexico.

Chances of any Cape Verde type storms look quite low because of a persistent SAL bringing lots of dry air into the eastern and central tropical Atlantic, while a TUTT maintains relatively high shear, especially between 40 and 65W longitude. The dry air is clearly visible on both the GFS and ECMWF runs:

http://www.meteo.psu.edu/~gadomski/ECMW ... floop.html
http://www.meteo.psu.edu/~gadomski/GFST ... sloop.html

[cycloneye]

The EURO enters the fray with GFS and CMC with the African train as August arrives.It has a closed low in Eastern Atlantic,but not more stronger.

http://www.ecmwf.int/products/forecasts ... 00!!!step/

[srainhoutx]

Hmmm...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
916 AM EDT FRI JUL 24 2009

VALID 12Z TUE JUL 28 2009 - 12Z FRI JUL 31 2009

TELECONNECTIONS WITH A BUILDING RIDGE IN THE EASTERN PACIFIC WITH
ITS MAIN POSITIVE ANOMALY CENTER PASSING 58N 135W FAVORS TROUGHING
IN THE UPPER MIDWEST/GREAT LAKES AS WELL AS A MID-LEVEL CYCLONE
UNDER ITS BASE IN THE UPPER 30S LATITUDE. THIS SLOW RETROGRESSION
TO THE MEAN TROUGH POSITION AS OF LATE SHOULD LEAD TO THE FIRST
SUSTAINED APPEARANCE OF THE SUMMER FOR THE SUBTROPICAL
RIDGE/BERMUDA HIGH INTO THE SOUTHEASTERN UNITED STATES...WHOSE
ONSET IS ABOUT A MONTH LATER THAN NORMAL.

THE MODELS AGREE WITH THE TELECONNECTIONS NOTED. THE GUIDANCE
SHOWS SMALL DIFFERENCES WITH THE DEPTH OF THE MIDWESTERN
TROUGH...WITH THE 00Z CANADIAN THE STRONGEST AND THE 00Z ECMWF THE
WEAKEST /EVEN WEAKER THAN THE 00Z ECMWF AND 06Z GEFS ENSEMBLE
MEANS/. USED A BLEND/COMPROMISE OF THE 06Z GFS/00Z ECMWF
SOLUTIONS FOR THE PRESSURES THIS PERIOD...AND MADE SOME
MODIFICATIONS TO THE SURFACE LOW CENTERS BY USING 00Z MULTI-MODEL
ENSEMBLE LOW CLUSTERING...WHERE POSSIBLE. THIS KEPT REASONABLE
CONTINUITY IN THE PRESSURES... DESPITE THE REARRANGEMENT MADE IN
THE FRONTAL POSITIONS. THIS PATTERN LOOKS WETTEST FROM THE
WESTERN GULF COAST INTO THE OHIO VALLEY AND NORTHEAST AT THE
LEADING EDGE OF THE MIDWEST TROUGHING.

RIDGING NEAR THE ARIZONA/MEXICO BORDER SHOULD KEEP DAILY MONSOONAL
THUNDERSTORM ACTIVITY AT BAY OVER THE DESERT SOUTHWEST.
ALSO...THE RIDGING IS IN A FAVORABLE SPOT FOR TROPICAL
CYCLOGENESIS IN THE EASTERN TROPICAL PACIFIC...AND THE 00Z
MULTI-MODEL ENSEMBLE GUIDANCE SHOWS ONE...IF NOT TWO...ATTEMPTS AT
LOW DEVELOPMENT IN THIS REGION. THE ROUNDY TROPICAL CYCLONE
PROBABILITY DIAGRAMS ALSO SHOW THAT THE BEST CHANCE OF TC
DEVELOPMENT AROUND AUGUST 2...IMPLYING THAT THE MJOS IMPACT ON
DIVERGENCE OVER THE REGION IS ALSO FAVORABLE FOR FORMATION LATE IN
THE PERIOD. HOWEVER...OVERALL PROBABILITIES OF TROPICAL CYCLONE
DEVELOPMENT THROUGHOUT THE NORTHERN HEMISPHERE REMAIN NO BETTER
THAN AVERAGE THROUGH THE FORESEEABLE FUTURE. THE EASTERN PACIFIC
FORMATIONS WILL BE DISCUSSED WITH TPC DURING THE 16Z MEDIUM RANGE
TROPICAL COLLABORATION CALL.

ROTH

[Ed Mahmoud]

If the CFS model is correct,a pattern change will be instored from the fall-like weather in the east coast of U.S.that will be suplanted by high pressure in August.



http://wxcaster4.com/cfs/CONUS_CFS_500_ ... 1MONTH.gif

That would seem to suggest Florida from the Caribbean/Gulf and the East Coast, depending on the exact location and orientation of that trough.

A little bit of a negative tilt on a trough near the East Coast could go a long way as far as a Northeast hurricane, assuming we have anything form next month.

If the upper (outflow level) trough is in a similar position to the mean 500 mb trough, The Bahamas and vicinity could be favorable for formation.


This could be the year JB gets his "Perfect Storm", a major passing over/just West of Delaware Bay, driving a Naragannsett Bay/Providence style storm surge into Philadelphia.



I could be mistaken, but I think PHL is one of the cities like Boston and San Francisco that still have street cars.

[deltadog03]

IF that pic above is right, I would be happy....I like the tropics, but give me a BIG trof like that in east during the mid-late summer.....that would be nice!

[Ed Mahmoud]

IF that pic above is right, I would be happy....I like the tropics, but give me a BIG trof like that in east during the mid-late summer.....that would be nice!

Wiki says some of PHL's street car routes run in subway tunnels, like the MBTA Green Line and the Muni Metro, and I'll bet salt water would really mess up the switchgear.

[Ed Mahmoud]

Day 10, Euro drops 850 mb winds in the Caribbean below 30 knots. How far below, I don't know. But Easterlies less than 30 knots have to be better than Easterlies above 30 knots for development chances in the Caribbean.

A decent looking surface wave around 45ºW, but already past 20ºN, and a possible escape route to the Westerlies for that wave if it does develop. But generally an Eastern trough.




A late developer would have a shot at the Carolinas, maybe.

[Ed Mahmoud]

GFS says 1 week to a tropical depression near 35ºW!

A steady diet of mid-level Westerlies to steer it towards North America or the Islands?


Post 180 hour resolution lobotomy...


Rapid fizzleation by 10 days, as a new impressive wave approaches the African coast. It fizzles a couple of days later.

[cycloneye]

GFS develops a fish system in the Eastern Atlantic.But it is after 240 hours so the resolution is not great.More model support below 144 hours is ideal to then be in the believe camp.





http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

[wxman57]

It's really sad when you guys resort to discussing days 10-15 of the GFS forecast with hopes that maybe this one time it's right.

[cycloneye]

It's really sad when you guys resort to discussing days 10-15 of the GFS forecast with hopes that maybe this one time it's right.

You may hit the jackpot on August 8.

[boca]

I'm going with Aug 24th with the A storm. Its my daughter's birthday,unscientific of course.

[Macrocane]

Leaving the Atlantic alone for a moment, have you seen what the models are predicting for the EPAC? they are in good agreement about development, it seems that the EPAC will turn active again in about 120-144 h, the Euro even shows a system in the CPAC.

[srainhoutx]

Leaving the Atlantic alone for a moment, have you seen what the models are predicting for the EPAC? they are in good agreement about development, it seems that the EPAC will turn active again in about 120-144 h, the Euro even shows a system in the CPAC.

MJO Pulse heading in. HPC is "hinting" 1 to 2 systems in the EPAC around August 2nd.

[Macrocane]

MJO Pulse heading in. HPC is "hinting" 1 to 2 systems in the EPAC around August 2nd.

Yes, it seems like the MJO signal will get a little stronger ater being weak for several weeks, If it intensifies I hope that it reaches Central America because we have had below average rainfall this past two weeks.

[dixiebreeze]

I'm beginning to wonder if this is going to be an Andrew type season.

[boca]

I'm beginning to wonder if this is going to be an Andrew type season.

Dixie don't let the people in South Dade county here you say that.In 1914 I believe their was only one storm.

http://www.wunderground.com/hurricane/at1914.asp

[Macrocane]

I'm beginning to wonder if this is going to be an Andrew type season.

Dixie don't let the people in South Dade county here you say that.In 1914 I believe their was only one storm.

http://www.wunderground.com/hurricane/at1914.asp

Why? They shouldn't let down their guard

[dixiebreeze]

I'm beginning to wonder if this is going to be an Andrew type season.

Dixie don't let the people in South Dade county here you say that.In 1914 I believe their was only one storm.

http://www.wunderground.com/hurricane/at1914.asp

Boca, it's just been so extra quiet in the tropics. I know that can change in a heartbeat, but it seems surreal right now.