GOMEX AREA OF INTEREST / T.S. PHILIPPE / INVEST 91L FORECAST SYNOPSIS…ISSUED SEP. 25, 2023…12:45 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– 16
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:          16
HURRICANES:                 6
MAJOR HURRICANES:  3

Given that the NHC has named at least 3, if not more, 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.  Unless we have a system threatening any area, the forecast office will be closed on the weekends.

Today we’ll begin with the area of interest in the GOMEX.  Based on satellite loop imagery, disorganized showers remain over the area indicated by the NHC GTWO map.  Based on my analysis, this area of low pressure is associated with a trough, and appears to be more prominent in the mid to upper levels, based on water vapor loop imagery.  Analysis of forecast wind shear and upper level wind pattern maps indicate conditions to become more unfavorable for development in a couple of days.  Based on current water vapor imagery, forecast 500 mb relative humidity values, and PWAT, the surrounding environment should remain fairly dry.  You’ll note the rotation in the area, in the 500 mb RH animation.  Based on these factors, I do not anticipate development in this area.  I’ll continue to monitor this area for any significant changes.
WEATHERNERDS GOMEX IR AND WATER VAPOR LOOP
AOI.IR
AOI.WV
ECMWF 500 MB RH ANIMATION
ecmwf-deterministic-gulf-rh500-1695600000-1695600000-1695772800-40
Tropical Storm PHILIPPE continues to move W to WNW and satellite loop imagery indicates the LLC is fully exposed to the west of the heavy convection.

As of 11:00 a.m. EDT, the following information was available on PHILIPPE from the NHC:
11:00 AM EDT Mon Sep 25
Location: 17.3°N 45.5°W
Moving: W at 13 mph
Min pressure:  1000 mb/29.53 in
Max sustained: 50 mph
Satellite loop imagery indicates the LLC is displaced just west of the convective area. 

WEATHERNERDS PHILIPPE SATELLITE LOOP IMAGERY
91L.IR
91L.vis

PHILIPPE is currently under about 20 – 25 kts of SWLY shear, causing the exposure of the LLC.  As we’ve seen with prior systems with this shear, SST’s are very warm with very good OHC, and a fairly established outflow pattern, which has the tendency to negate the shear as far as further strengthening.  Analysis of PWAT and 500 mb RH forecast maps indicates ample moisture for about the next 96 hours.  Thereafter, drier air takes over, as well as an increase in wind shear, based on current analysis.  NHC stated in their discussion that the GFS indicated the storm may move into a lower shear environment, however the current SHIPS diagnostic, product of the GFS, indicates shear to continue to increase.  Based on this, for right now I agree with the NHC intensity forecast, showing PHILIPPE remaining steady.  Any strengthening would most likely be under baroclinic conditions:
CIMSS WIND SHEAR AND UPPER LEVEL WINDS
PHILIPPE.shear
PHILIPPE.UPPER
NHC INTENSITY FORECAST
INIT 25/1500Z 17.3N 45.5W 45 KT 50 MPH

12H 26/0000Z 17.6N 47.2W 45 KT 50 MPH
24H 26/1200Z 18.1N 49.2W 45 KT 50 MPH
36H 27/0000Z 18.9N 51.2W 45 KT 50 MPH
48H 27/1200Z 19.9N 52.9W 45 KT 50 MPH
60H 28/0000Z 21.1N 54.2W 45 KT 50 MPH
72H 28/1200Z 22.1N 55.4W 45 KT 50 MPH
96H 29/1200Z 23.7N 56.9W 45 KT 50 MPH
120H 30/1200Z 24.6N 57.9W 45 KT 50 MPH

PHILIPPE continues to the W.  Based on analysis of forecast steering and current guidance, the storm should continue on this general motion for the next 24 – 36 hours, before making a more WNW to NW track, following the current NHC forecast track.  Given the slight bend left at day 5 in the guidance, I will continue to monitor this system closely, however at the moment, I do believe this will eventually continue to re-curve.
12Z ATCF GUIDANCE

aal17_2023092512_track_early
NHC FORECASTTRACK
cone graphic
INVEST 91L continues to produce limited, disorganized thunderstorm activity.  Analysis of PWAT and 500 mb humidity values indicates enough moisture for development.  However, the current 200 mb pattern is zonal over the system right now, and a radial shear pattern is centered just west of the circulation, and could be inducing some slight shear.  In around 72 -96 hours however, the wind shear pattern and 200 mb streamline pattern are forecast to improve and become more favorable for development.  Based on this, INVEST 91L should continue to organize and develop, however I do believe this is going to be a slow process during the next 3 – 4 days.  I will continue to monitor this disturbance for any significant changes to the forecast conditions.
WEATHERNERDS INVEST 91L SATELLITE LOOP IMAGERY
91L.IR
91L.vis

Elsewhere, analysis of 500 mb anomaly charts indicate we may have to watch the GOMEX / Bahamas area once again, as within the next 7 – 10 days, height anomalies are expected to rise north over the Great Lakes / Canada region, once again creating the “ridge over troubled water.  The ECMWF does indicate lowering of pressures over FL. then the GOMEX during that time period.  This is basically the same pattern that helped spawn Idalia and Ophelia.  In the first graphic, look for the small area over the Tampa Florida area.
this.one.ecmwf-deterministic-conuswide-z500_anom-6248000
me.too.ecmwf-deterministic-conuswide-z500_anom-6399200The following map will allow to get information from your NWS office.

NWS WATCH / WARNING DISPLAY (LINKED…CLICK MAP, THEN YOUR AREA)

NWS DOPPLER RADAR LOOP (LINKED, CLICK RADAR MAP)
canvas.RADR.US
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 day!

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

About palmharborforecastcenter

I am a Tropical Forecast meteorologist, providing hurricane forecasts during the Atlantic Hurricane Season. I retired from the U.S. Coast Guard in July of 2001. Meteorology became my passion in high school, and I have continued my educational background in meteorology since 1996, when I undertook the study of Tropical Meteorology. While working toward my degree, I had to unexpectedly withdraw from college due to my oldest sons medical reasons. I do however, meet the educational criteria of the AMS to be recognized as a meteorologist. Studies include, but are not limited to the Navy Aerographers Mate course, Naval METOC meteorology course, Meteorology 2010 Sophomore level course while attending St. Petersburg College, Clearwater, FL., Basic Forecasting course for operational meteorologists from Rapid WX, meteorology institute, a four month meteorological internship, and extensive research on numerous meteorological topics such as the MJO, NAO, satellite imagery interpretation, etc. I have been forecasting Tropical Weather (Tropical Storms and Hurricanes) since 1996, with my main client being three different Coast Guard Commands.
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