TROPICAL DEPRESSION 12 FORMS IN EATL / NEW AREA OF CONCERN EXITS AFRICAN COAST…FORECAST SYNOPSIS…ISSUED SEP. 01, 2023…1:00 P.M. EDT

ALL forecasts herein are the result of my analysis, (to which you will see me at times, insert excerpts from various agencies due to the nature of the importance of the information) and I am solely responsible for the content.  As ALWAYS, follow the National Hurricane Center, National Weather Service, and your local Emergency Management officials for emergency decisions.  In addition, this is strictly a FORECAST OFFICE.  I CANNOT make decisions regarding travel plans, etc.  My purpose, is to provide you the information, based solely on information I analyze, and the accuracy of the information at hand of the time of analysis, so you may make informed decisions.
(T. F. “Storm” Walsh)

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I will reiterate, my forecasts are based on the available information at the time of analysis, and are only as accurate as the information analyzed and the solutions provided.  Keep in mind, if a forecast doesn’t exactly pan out, remember, the atmosphere is fluid in motion.  When models are being analyzed, that’s just one run, and I have to go with what is presented.  After that, models don’t update again for another 4 – 6 hours, so, what happens between that time is unknown, and forecast conditions can change slightly, to greatly.  This will have an effect on my actual forecast.

The following is my outlook forecast for the 2023 Atlantic Hurricane Season:
STORM W SEASONAL FORECAST
TOTAL NAMED STORMS: 14– 15
TOTAL HURRICANES :        5 – 7
MAJOR HURRICANES:        3 – 4

AVERAGE HURRICANE SEASON:
TOTAL NAMED STORMS: 14
TOTAL HURRICANES:         7
MAJOR HURRICANES:        3

SEASON TOTALS
NAMED STORMS:          10
HURRICANES:                 3
MAJOR HURRICANES:  2

Given that the NHC has named at least 3 garbage systems, I had to increase my seasonal forecast slightly.

The following are the storm names for the 2023 hurricane season.  As each storm is named, they will be colored in red in order to keep track of the used names in the list:

Arlene Bret Cindy Don Emily Franklin Gert Harold Idalia Jose Katia
Lee Margot Nigel Ophelia Philippe Rina Sean Tammy Vince Whitney

Greetings everyone!
As a reminder, when forecasting tropical systems, if there are numerous systems to deal with, I always update on the systems that may present an impact or threat to either the U. S. or the Caribbean islands.  Anything far out in the Atlantic or something that may re-curve, take a lower priority as there is more time to deal with them.

INVEST 94L in the far EATL was just upgraded to Tropical Depression 12.  Based on forecast conditions, it could become a minimal Tropical Storm briefly.  However current guidance suggests this should remain on a NNW track, and does not pose a threat to the U.S  or the Greater and Lesser Antilles.

Looking at IDALIA, I have no idea why the NHC has a Tropical Storm warnings posted.  It’s not a TS, or even post tropical…it’s extratropical.  The system is void of any deep convection over the COC, and is covered in very dry air based on water vapor imagery.  I’ll keep tabs on it, but I don’t think this comes back to tropical status.  We’ll see, should conditions change rapidly.


Elsewhere, the NHC has added a new area of interest in the GTWO map.  A tropical wave I am monitoring just on the edge of the African coast, may have a chance at further development once near, or in the circled area in about 5 to 7 days:
NHC 7 DAY GTWO

Analysis this morning of the ECMWF EPS Cyclone probability forecast map does indicate at this time, a HIGH probability for a Tropical Depression, and a MEDIUM probability a Tropical Storm and Hurricane developing.
ECMWF EPS CYCLONE PROBABILITY



EATL SATELLITE LOOP IMAGERY


AFRICASAT

Analysis of both the ECMWF and GFS global models currently indicate this system could attain hurricane strength of possibly CAT 2 to CAT 3 during the next 8 – 10 days, however given that the models just are in the initialization phase, and the time frame in the forecast period is less accurate, this should be regarded as a lower confidence solution.
ECMWF AND GFS MSLP ANOMALIES FORECAST


Right now, a lot will depend on actual track as far as development and strength.  However, the forecast conditions by both models at the moment do indicate improving conditions in the forecast, with these conditions almost mimicking those of IDALIA, with high PWAT, developing radial shear pattern, and ample mid level moisture (RH).   The graphics I’m posting are out to day 7 I believe.  Currently, the wave is under easterly shear of about 25-30 kts:
CURRENT WIND SHEAR

ECMWF AND GFS MSLP ANOMALIES, PWAT, WIND SHEAR, AND MID LEVEL RH FORECAST:




ECMWF 200 MB OUTFLOW

GFS FORECAST




IF these forecast conditions materialize and remain a factor, I believe we could see a Tropical depression develop within the next 96 -120 hours from 12Z this morning.

Based on forecast steering and analysis of MSLP maps regarding the orientation of the sub-tropical ridge, this entity could continue on a W to WNW motion during the next 5 days.  Since there is a good spread in track with the ECMWF and the GFS, I want to see how this may actually develop before putting too much faith in a forecast track.  However, this system is coming off Africa at about 9 – 10 degrees latitude, which is pretty low, which could allow for a more westerly component.  For the time being, I would recommend residents of the Greater and Lesser Antilles monitor this system, until we get at least 72 hours past the initialization period.  I will continue to monitor this AOI closely over the next 5 – 7 days for any significant changes.

As mentioned in my previous forecast, the majority of the MJO phase space diagram models indicate the MJO moving into phase 4 and 5 in a few days.  Ridging in the 500 mb pattern is supposed to develop basically over the north, which in the forecast position would tend to lower pressures toward it’s S to SW (which we affectionately name “ridge over troubled water”).  Based on a method by Frederic Vitart, sometimes cyclone development can occur over a very small area of the Gulf of Mexico. Whether or not we see anything from this remains to be seen.  However, I’m keeping my heads up. The orange in the Vitart graphic is from past OBSERVED cyclones from the MJO going into phases 4 and 5.  You’ll note a weakness close to the Texas coast in the 500 MB ensemble images from the ECMWF and GFS.
MJO PHASE SPACE DIAGRAMS






VITART DIAGRAM PHASE 4 AND 5

The following map will allow to get information from your NWS office.
NWS WATCH / WARNING DISPLAY (LINKED…CLICK MAP, THEN YOUR AREA)

WSI DOPPLER RADAR LOOP (LINKED, CLICK RADAR MAP)

RAP RADAR (CLICK IMAGE THEN RADAR SITE…ONCE YOU CLICK THE SITE, GO TO LOOP DURATION TO CREATE A LOOP)
You may direct any questions by contacting me personally, ANYTIME, at: twalsh22000@yahoo.com

Have a blessed evening!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS