Wednesday, August 23, 2023

Tropical Storm Franklin A Potential Long-Range Threat Update Two





































000
WTNT33 KNHC 240252
TCPAT3

BULLETIN
Tropical Storm Franklin Advisory Number  14
NWS National Hurricane Center Miami FL       AL082023
1100 PM EDT Wed Aug 23 2023

...FRANKLIN STRENGTHENING AS IT MOVES AWAY FROM THE DOMINICAN 
REPUBLIC...
...FLASH FLOODING THREAT CONTINUES OVERNIGHT...

SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...21.2N 70.4W
ABOUT 50 MI...80 KM ESE OF GRAND TURK ISLAND
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NNE OR 15 DEGREES AT 13 MPH...20 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES

WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for...
* Dominican Republic south coast from Punta Palenque eastward
to Cabo Engano
* Dominican Republic entire north coast from Haiti border eastward
to Cabo Engano
* Turks and Caicos Islands

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

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

DISCUSSION AND OUTLOOK
----------------------
At 1100 PM EDT (0300 UTC), the center of Tropical Storm Franklin was
located by an Air Force Reserve Hurricane Hunter aircraft near 
latitude 21.2 North, longitude 70.4 West. Franklin is moving toward 
the north-northeast near 13 mph (20 km/h). A turn to the northeast 
and then east-northeast with a decrease in forward speed is 
forecast on Thursday and Friday.  On the forecast track, the center 
of Franklin will continue to move farther away from the Dominican 
Republic and then move over the southwestern Atlantic into the 
weekend.

Maximum sustained winds have increased to near 45 mph (75 km/h)
with higher gusts. Gradual strengthening is forecast during the next
several days, and Franklin could be near hurricane strength over the
southwestern Atlantic by Saturday.

Tropical-storm-force winds extend outward up to 90 miles (150 km), 
primarily east of the center.

The estimated minimum central pressure from dropsonde data is 1002 
mb (29.59 inches).

HAZARDS AFFECTING LAND
----------------------
Key messages for Franklin can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT3 and WMO header WTNT43 KNHC
and on the web at hurricanes.gov/text/MIATCDAT3.shtml.

RAINFALL:  Franklin is forecast to produce the following rainfall
totals through Thursday:

Hispaniola: Additional 1-3 inches.

Turks and Caicos: 1 to 3 inches, mainly across the eastern islands.

Puerto Rico: Up to an inch in western portions.

WIND:  Tropical storm conditions, primarily in gusts, are 
expected to occur in portions of the Dominican Republic and Turks 
and Caicos Islands overnight.

NEXT ADVISORY
-------------
Next intermediate advisory at 200 AM EDT.
Next complete advisory at 500 AM EDT.

$$
Forecaster Blake


000
WTNT43 KNHC 240253
TCDAT3

Tropical Storm Franklin Discussion Number  14
NWS National Hurricane Center Miami FL       AL082023
1100 PM EDT Wed Aug 23 2023

Franklin is showing signs of intensification on the latest satellite 
imagery with increasing deep convection near and southeast of the 
center.  This trend is confirmed by an Air Force Reserve Hurricane 
Hunter aircraft mission that has been flying through the storm 
during the past few hours with maximum flight-level winds of 46 kt, 
believable SFMR winds of at least 40 kt, and the central pressure 
falling to 1002 mb.  The initial wind speed is set to 40 kt as a 
blend of the data.

The storm continues heading north-northeastward or 015/11 kt, 
steered by a ridge over the eastern Caribbean.  Franklin should move 
around the northern periphery of the ridge, turning 
east-northeastward tomorrow and slowing down by Friday.  As the 
remnants of Emily exit the central Atlantic, mid-level ridging 
should build back northeast of Franklin, turning the cyclone 
north-northwestward and northward this weekend.  For such an unusual 
August track, the model guidance is in reasonably good agreement, 
and little change was made to the last NHC track forecast.

Moderate westerly shear is forecast to limit the strengthening rate 
of Franklin during the next couple of days, though very warm waters 
should allow for gradual intensification.  In 2 or 3 days, an 
upper-level trough should cutoff to the southwest of Franklin, 
creating a lower shear and very diffluent flow pattern near the 
storm.  This environmental change will likely promote significant 
strengthening by late this weekend, and Franklin is forecast to 
become a powerful hurricane southwest of Bermuda.  The new intensity 
forecast is raised from the previous one at most time periods, and 
the stronger regional hurricane models showing major hurricane 
strength at long range are certainly reasonable possibilities.

KEY MESSAGES:

1. Localized heavy rainfall from the outer bands of Franklin could
cause further isolated flash flooding through Thursday in vulnerable
areas of the Dominican Republic that already received torrential
rainfall.

2. Franklin is expected to continue to bring tropical storm 
conditions to portions of the Dominican Republic and the Turks and 
Caicos Islands overnight.

FORECAST POSITIONS AND MAX WINDS

INIT  24/0300Z 21.2N  70.4W   40 KT  45 MPH
 12H  24/1200Z 22.3N  69.6W   45 KT  50 MPH
 24H  25/0000Z 23.0N  68.1W   50 KT  60 MPH
 36H  25/1200Z 23.3N  66.8W   55 KT  65 MPH
 48H  26/0000Z 23.7N  65.8W   55 KT  65 MPH
 60H  26/1200Z 24.4N  65.4W   60 KT  70 MPH
 72H  27/0000Z 25.8N  65.9W   70 KT  80 MPH
 96H  28/0000Z 29.2N  67.5W   90 KT 105 MPH
120H  29/0000Z 33.0N  67.4W   95 KT 110 MPH

$$
Forecaster Blake


000
FXUS61 KCAR 240201
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
1001 PM EDT Wed Aug 23 2023

.SYNOPSIS...
High pressure builds in through tonight, then slides to the
east on Thursday. A complex low pressure system approaches
Thursday night and Friday. A cold front crosses the area Saturday,
as a coastal low tracks across the Gulf of Maine. High pressure
builds towards the area Sunday and crests over the area Monday.....

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/......

.....Uncertainty increases towards the middle of next week, but
ensembles agree that a large upper level trough will approach
the area Tuesday night into Wednesday. With surface high
pressure to the east, southerly return flow will bring moisture
northward and chances of rain increase. This is an opportunity
to pull in potential tropical moisture from the Gulf of Mexico
or western Atlantic, especially with weaker tropical systems.
Tropical Storm Franklin is expected to strengthen as it moves
northward and due to its strength will be influenced by
persistent southwest winds around 200 to 250mb, most likely
keeping the system well off to the east as shown by the vast
majority of ensemble members. The pattern is somewhat concerning
for a predecessor heavy rain similar to what is described in
Galarneau et. al. 2010, so even with the system recurving well
to the east, a heavy rainfall threat may still exist depending
how the timing of Franklin, the upper level trough, and another
potential plume of tropical moisture moving northward from the
Gulf of Mexico interact........

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