TROPICAL STORM ELSA FORECAST SYNOPSIS…ISSUED JUL. 01, 2021…9:05 P.M. EDT

TROPICAL STORM ELSA FORECAST SYNOPSIS…ISSUED JUL. 01, 2021…9:05 P.M. EDT


Disclaimer:  This site is not affiliated with the National Hurricane Center, Hurricane Hunters, Storm Prediction Center, or National Weather Service.  ALL forecasts herein are the result of my analysis, 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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Barbados

Central Florida

Greetings to everyone!
Please be aware, even though I do not post every night, rest assured I am continuously monitoring various areas for any significant weather.  I will be taking Sundays off (family time), unless we have active systems that may be posing a threat (i.e. Tropical, Winter Weather, Coastal Storms, etc.).

STORM WALSH PRE-SEASON FORECAST
TOTAL NAMED STORMS: 17 – 20
TOTAL HURRICANES :        7 – 9
MAJOR HURRICANES:       4 – 5

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

2021 SEASON TOTALS:
TOTAL NAMED STORMS: 4
TOTAL HURRICANES: 0
MAJOR HURRICANES: 0

The following is the list of storm names for the 2021 Atlantic Hurricane Season:
Ana Bill Claudette Danny Elsa Fred Grace Henri Ida Julian Kate Larry
Mindy Nicholas Odette Peter Rose Sam Teresa Victor Wanda
As a storm becomes named, I will be marking it in bold red to keep track of the activity for this Atlantic season.

Please note..when we are dealing with multiple systems, they will be listed in order as to the greatest threat to land or the U. S. , to the least threat.

PTC FIVE of yesterday evening, has become Tropical Storm ELSA.  As of the 8:00 p.m. EDT intermediate advisory, the following was available on ELSA:
8:00 PM AST Thu Jul 1
Location: 11.4°N 54.7°W
Moving: WNW at 28 mph
Min pressure: 1005 mb / 29.68 in
Max sustained: 45 mph

There are currently no local products for this system, however watches and warnings are posted.  From the NHC:

CHANGES WITH THIS ADVISORY:

The government of the Dominican Republic has issued a Tropical 
Storm Watch for the southern coast of the Dominican Republic from 
the Haiti/Dominican Republic border eastward to Punta Palenque. 

The government of Jamaica has issued a Tropical Storm Watch for 
Jamaica.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Barbados
* Martinique
* St. Lucia
* St. Vincent and the Grenadines

A Tropical Storm Watch is in effect for...
* Grenada and its dependencies
* The southern and western coasts of Haiti from the southern border
of the Dominican Republic to Le Mole St. Nicholas
* The southern coast of the Dominican Republic from the southern 
border of Haiti eastward to Punta Palenque 
* Jamaica

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area within 36 hours.

A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, in this case within 36 hours.

Interests elsewhere in the Windward Islands, Leeward Islands, the
Virgin Islands, Puerto Rico, the Dominican Republic, Haiti, 
and eastern Cuba should monitor the progress of Elsa. Additional
watches and warnings will likely be required later tonight and
Friday.

For storm information specific to your area, please monitor
products issued by your national meteorological service.
HAZARDS AFFECTING LAND

Key messages for Elsa can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT5, WMO header WTNT45 KNHC and
on the web at
www.hurricanes.gov/graphics_at5.shtml?key_messages.

WIND: Tropical storm conditions are expected in portions of the
Windward and southern Leeward Islands within the warning areas
on Friday. Tropical storm conditions are possible in the watch
areas in the Lesser Antilles on Friday. Tropical storm conditions
are possible in the watch area in the Dominican Republic and Haiti 
on Saturday, and are possible in Jamaica Saturday night. 

STORM SURGE: A storm surge will raise water levels by as much as 1
to 3 feet above normal tide levels in areas of onshore winds along
the southern coast of Hispaniola.

RAINFALL: Elsa is expected to produce rainfall totals of 3 to 6
inches with maximum amounts of 10 inches on Friday across the
Windward and southern Leeward Islands, including Barbados. This rain
may lead to isolated flash flooding and mudslides.

Over Puerto Rico, rainfall of 1 to 3 inches with localized amounts
of 5 inches is expected Friday into Saturday. This rain may lead to
isolated flash flooding and minor river flooding, along with the
potential for mudslides.

Along portions of southern Hispaniola, rainfall of 4 to 8 inches
with isolated maximum amounts of 12 inches is possible on Saturday.
This rain may lead to scattered flash flooding and mudslides.

205258_current_wind_sm

205258_key_messages_sm

WEATHERNERDS ELSA AND ATLANTIC SATELLITE ANIMATIONS
40411304
40411304SWIR
40411304ATL
Central pressure has been falling very slowly since late last night, but has seemed to level off from the 5:00 p.m. advisory.  Satellite loop imagery indicates that convection has become stronger near the center, and appears to be slightly better organized.  Right now, I won’t know if this s a short trend, or if the cyclone is trying to slowly strengthen.  My reasoning is, the storm is traveling at a forward speed of 28 mph.  Usually, storms have trouble strengthening at that fast speed in that the LLC and heavy convection usually have a problem remaining what we call vertically stacked…one out runs the other.

ELSA is currently racing to the WNW.  Based on my analysis of the current steering layer mean, and forecast steering maps, in addition to guidance, I expect this motion to continue during the next 48 hours.  Thereafter, confidence still remains low, as the guidance and model motion remains highly divergent.  The ECMWF and its ensembles show ELSA moving more toward the north, while the remaining global and dynamic models show the current NHC forecast track.
18Z RAL ATCF TRACK GUIDANCE
aal05_2021070118_track_early
ECMWF ENSEMBLE GUIDANCE
ecmwf-bufr-elsa05l-1625140800-5140800
GEFS
gfs-ensemble-elsa05l-1625140800-5140800
CMC
cmc-ensemble-elsa05l-1625140800-5140800
CURRENT STEERING LAYER
wg8dlm2
At the moment, I basically agree with the current NHC track guidance up to 48 hours.  Thereafter is when the guidance begins to diverge.  While the ECMWF as a rule, is much better at forecast track than the remaining global models based on my years of forecasting, the GFS has not budged from forecast track.  One thing I did want to point out is, the consensus models TVCA and TVCE have been pretty spot on over the years, and the NHC forecast track usually follows these models and / or the Florida State Superensemble (FSSE).  I do not have access to that particular model, however, yesterday evening, the TVCA;TVCE were kind of in the camp of the ECMWF, and bringing ELSA just offshore of the Florida east coast.  On the 18Z run, these models both shifted west, and are pretty much riding over the NHC forecast track.  IF you go to the 18Z RAL GUIDANCE graphic above, you’ll not 2 arrows…one orange, and one red.  The orange indicates the TVCA/TVCE guidance of last night, the red one indicates the shift west, and points to those particular models.  Again, the future track [past 48 hours will all depend on how strong ELSA may be, and the timing and strength of both the approaching mid latitude trof forecast over the eastern U.S., and timing and strength of the fluctuations in the sub-tropical ridge.  While the ECMWF track could materialize, it’s hard to ignore the consensus models at the moment.  The following animations are the 500 mb height maps from the GFS and ECMWF.  The ECMWF is a tad stronger and a little further south with the trof, however it noses the ridge west and pulls it back, and nudges it west again, similar to the GFS.  For right now, I agree with the NHC forecast track, and once the storm gets in the central Caribbean, I should pretty much know how the forecast track should pan out.  One tell tale sign will be when ELSA slows somewhat as she approaches the weakness in the ridge from the trof.  This will allow for steering maps and guidance to run numerous times, and I’ll look for any changes.
NHC FORECAST TRACK MAP
234535_5day_cone_with_line_and_wind
GFS AND ECMWF 500 MB HEIGHTS FORECAST
gfs-deterministic-namer-z500_barbs-1625162400-1625162400-1625378400-40
ecmwf-deterministic-namer-z500_barbs-1625140800-1625140800-1625378400-40
Maximum sustained winds with ELSA were reported by the NHC at 45 mph.  Based on my analysis of the current wind shear over ELSA, the storm is currently under a low shear environment.
CIMSS WIND SHEAR
ELSA.shear
Other maps from the CIMSS site indicate moderate divergence aloft, and a high vorticity value of 150.
Based on analysis of forecast shear maps from the ECMWF and GFS, the current pattern is forecast to remain in place until ELSA reaches close to the central Caribbean, where the upper level pattern becomes marginal.  The ECMWF shows a slightly unfavorable pattern thereafter, while the GFS indicates the upper pattern becoming favorable again near Cuba.  Both models at that point, more so the GFS, also indicate the development of somewhat of a 200 mb radial outflow pattern.  Both models indicate high relative humidity up to the 500 mb level for the duration, and high TPW values. Should this occur, ELSA could begin to strengthen at that point, which wold be the Sunday point on the forecast track map.  On another note, this will also depend on whether or not ELSA slows  enough to become better vertically stacked, or if she maintains current speed, or increase her forward speed.  This storm is a little more tough in forecasting, as given the uncertainties beyond 48 hours, one should not prescribe a “definite” forecast.  Based on the improved satellite appearance however, mixed with the uncertainties, I have to concur with the current NHC intensity forecast:
NHC INTENSITY FORECAST
INIT 01/2100Z 11.2N 53.8W 40 KT 45 MPH
12H 02/0600Z 12.1N 57.5W 45 KT 50 MPH
24H 02/1800Z 13.5N 62.4W 50 KT 60 MPH
36H 03/0600Z 15.1N 67.3W 50 KT 60 MPH
48H 03/1800Z 16.7N 71.6W 50 KT 60 MPH
60H 04/0600Z 18.3N 75.0W 50 KT 60 MPH
72H 04/1800Z 19.8N 77.9W 50 KT 60 MPH
96H 05/1800Z 22.5N 82.0W 50 KT 60 MPH
120H 06/1800Z 26.5N 83.5W 50 KT 60 MPH

I will be using the central Caribbean as my benchmark, to see how strong she may be, forward motion, and for consistency and agreement in forecast steering maps, model guidance, and ridge / trof setup.

I will continue to monitor ELSA for any significant changes in the forecast, and intend to have another update tomorrow evening.

You may direct any questions by contacting me personally, ANYTIME, at: [email protected]

Have a blessed evening!

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



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