September 23, 2021

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TROPICAL STORM NICHOLAS / INVEST 96L / INVEST 95L FORECAST SYNOPSIS…ISSUED SEP. 14, 2021…2:45 P.M. EDT

9 min read

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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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:  14
TOTAL HURRICANES:          6
MAJOR HURRICANES:        3

TOTAL U. S. LANDFALLS:    8

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.

Good day everyone,
NICHOLAS came ashore as a Category 1 Hurricane early this morning
near 1230 AM CDT (0530 UTC) on eastern part of the Matagorda Peninsula, about 10 miles (15 km) west-southwest of Sargent Beach, Texas.  Maximum sustained winds were 75 mph.  It is interesting to note, that the pressure at landfall was 991 mb, or 29.26 in., which over the past couple of days, the GFS showed that exact pressure in the forecast maps.  As of 11:00 a.m. EDT, winds were down to 45 mph.  The following is from the NHC 11:00 a.m. advisory:
NHC PUBLIC ADVISORY

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

The Tropical Storm Warning has been discontinued west of High
Island, Texas.

The Storm Surge Warning has been discontinued south of Port
Bolivar, Texas.

The Storm Surge Watch has been discontinued east of Cameron,
Louisiana.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Storm Surge Warning is in effect for...
* Port Bolivar Texas to Sabine Pass including Galveston Bay

A Tropical Storm Warning is in effect for...
* High Island Texas to Cameron Louisiana

A Storm Surge Watch is in effect for...
* Sabine Pass to Cameron Louisiana

A Storm Surge Warning means there is a danger of life-threatening
inundation, from rising water moving inland from the coastline. For 
a depiction of areas at risk, please see the National Weather 
Service Storm Surge Watch/Warning Graphic, available at 
hurricanes.gov.  This is a life-threatening situation.  Persons 
located within these areas should take all necessary actions to 
protect life and property from rising water and the potential for 
other dangerous conditions. Promptly follow evacuation and other 
instructions from local officials.

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

A Storm Surge Watch means there is a possibility of life-threatening
inundation, from rising water moving inland from the coastline. For 
a depiction of areas at risk, please see the National Weather 
Service Storm Surge Watch/Warning Graphic, available at 
hurricanes.gov.

For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.


DISCUSSION AND OUTLOOK
----------------------
At 1000 AM CDT (1500 UTC), the center of Tropical Storm Nicholas was
located near latitude 29.6 North, longitude 95.3 West. Nicholas is
moving toward the northeast near 6 mph (9 km/h) and this general
motion should continue today. The storm should move more slowly
toward the east-northeast by tonight, and then turn eastward on
Wednesday over Louisiana.  Little motion is anticipated on Thursday.

NOAA Doppler weather radar and surface observations indicate that
maximum sustained winds have decreased to near 45 mph (75 km/h)
with higher gusts. Additional weakening is forecast during the next
couple of days as Nicholas moves farther inland, and the storm is
forecast to become a tropical depression by tonight.

Tropical-storm-force winds extend outward up to 140 miles (220 km),
mainly over water to the southeast of the center. A TCOON observing 
station at Texas Point, Sabine Pass, Texas, recently measured a 
1-minute sustained wind of 40 mph (65 km/h) and a gust to 51 mph 
(81 km/h).

The estimated minimum central pressure is 1002 mb (29.59 inches)
based on nearby surface observations.


HAZARDS AFFECTING LAND
----------------------
Key messages for Nicholas can be found in the Tropical Cyclone
Discussion under AWIPS header MIATCDAT4, WMO header WTNT44 KNHC
and on the web at hurricanes.gov/graphics_at4.shtml?key_messages

RAINFALL:  Nicholas is expected to produce additional rainfall of
5 to 10 inches from the upper Texas coastal area into central to
southern Louisiana, far southern Mississippi, far southern Alabama
and the western Florida Panhandle through Thursday, with isolated
storm totals of 20 inches across southern Louisiana.
Life-threatening flash flooding impacts, especially in urbanized
metropolitan areas, are possible across these regions.

Widespread minor to isolated major river flooding is expected across
portions of the upper Texas Gulf Coast and southern Louisiana and
Mississippi.

For the latest rainfall reports and wind gusts associated with
Hurricane Nicholas see the companion storm summary at WBCSCCNS4 
with the WMO header ACUS44KWBC or at the following link
https://www.wpc.ncep.noaa.gov/discussions/nfdscc4.html

STORM SURGE:  The combination of a dangerous storm surge and the
tide will cause normally dry areas near the coast to be flooded by
rising waters moving inland from the shoreline.  The water could
reach the following heights above ground somewhere in the indicated
areas if the peak surge occurs at the time of high tide...

Port Bolivar, TX to Cameron, LA including Galveston Bay...2-4 ft
Port Aransas, TX to Port Bolivar, TX...1-3 ft
Aransas Bay, San Antonio Bay, and Matagorda Bay...1-3 ft
Cameron, LA to Intracoastal City, LA...1-3 ft
Sabine Lake and Calcasieu Lake...1-3 ft

The deepest water will occur along the immediate coast in areas
of onshore winds, where the surge will be accompanied by large and
dangerous waves.  Surge-related flooding depends on the relative
timing of the surge and the tidal cycle, and can vary greatly over
short distances.  For information specific to your area, please see
products issued by your local National Weather Service forecast
office.

WIND:  Tropical storm conditions are expected to continue along the 
Louisiana coast into this afternoon. Tropical storm conditions 
in the warning area across the upper Texas coast will diminish this 
afternoon as Nicholas moves farther to the northeast.

TORNADOES:  A tornado or two will be possible today into tonight
across southern Louisiana.

SURF:  Swells generated by Nicholas will continue affecting portions
of the northwest Gulf coast today. These swells are likely
to cause life-threatening surf and rip current conditions.  Please
consult products from your local weather office.

The following link is for local NWS products regarding NICHOLAS
https://www.nhc.noaa.gov/text/refresh/index_hls4+shtml/122122.shtml?

The following map will allow to 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)
COD RADAR (LINKED FOR ANIMATION CONTROLS)
COD-GOES-East-subregional-W_Gulf_Coast.radar.20210913.135000.gif-over=map-bars=
This will be my last update on NICHOLAS


The following are satellite animations of the Atlantic basin and Africa
ATLANTIC

AFRICA

Elsewhere in the tropics, there are 2 areas of interest to talk about.  First is INVEST 96L located near the Bahamas.  At 12Z this morning, INVEST 96L was located near 23.5N;71.5W.  Movement was to the NNW at 8 mph.  Maximum sustained winds were 25 mph.  Pressure was 1014 mb or 29.94 in.
INVEST 96L SATELLITE ANIMATION


Based on analysis of the satellite imagery, 96L appears to be getting slowly organized, and showing “that look”.  Analysis of the current wind shear and upper level winds product from CIMSS, seems to indciate conditions have become a little more favorable, with less than 10 kts of shear over the “center”.  Upper level winds do indicate a northern outflow channel, which then flows around the eastern periphery.  This is due to a radial outflow pattern being located just to the east of 96L.
CIMSS WIND SHEAR AND UPPER LEVEL WINDS


Analysis of forecast wind shear, 200 mb streamline pattern, and 500 mb relative humidity indicates the wind shear pattern is forecast to slowly improve, and become ore conducive for development as 96L approaches closer to the OBX of the Carolinas.  The 200 mb pattern does not indciate radial outflow for the system, however a northern outflow channel will remain present.  The 500 mb RH forecast shows plenty of moisture present from now, until the system begins to move away from the U. S. coastline, where intermittent dry air intrusion may occur.  Based on this, I believe further slow organization should continue during the next 5 days, and a depression could develop, however I feel at the moment this may occur closer toward the OBX (Outer Banks).  Analysis of the current intensity guidance models brings 96L to strong tropical storm status by day 4.  However, given this is the initialization period, and there is lack of a well organized LLC, this should be considered low confidence until such a time we have a well organized entity.  The NHC has designated a MEDIUM (60%) probability for cyclone development.
Based on analysis of forecast steering layers over the next 5 days, it does appear that 96L will follow the NHC hatched track area, which is currently along with model guidance.  Again, this should be considered low confidence and not taken a gospel, until something firmly develops
ATCF 12Z TRACK GUIDANCE



500 MB RH FORECAST

ECMWF AND GFS SHEAR FORECAST


I will continue to monitor INVEST 96L for any significant changes during the next 48 – 72 hours.

INVEST 95L is the wave that just moved of the African coast and is south of the Cape Verde Islands.  Satellite imagery shows a well defined system, showing signs of continuing organization.
INVEST 95L SATELLITE ANIMATION


Analysis of current shear and upper level winds product from CIMSS indicates 95L is in a favorable environment at the moment for further organization and development.  There is little to no shear over the COC, and the pattern indicates an anti-cyclonic flow.  Upper level winds indicate a radial outflow pattern may be trying to develop.  The 200 mb forecast pattern does not indicate a radial outflow down the road, but maintains an outflow pretty much as seen in the current graphic.
CIMSS WIND SHEAR AND UPPER LEVEL WINDS


Based on analysis of the shear forecast and 500 mb moisture forecast, conditions appear to remain favorable out to 120 – 144 hours in the forecast period.  After this, both the GFS and ECMWF kill the system.  This is most likely due to forecast conditions showing an increase in dry air on the western portion of the system, with some intrusion, and the increase of wind shear.  In the meantime, if the favorable environment holds, I expect 95L to develop a little quicker than INVEST 96L, and we should see a Tropical Depression come to fruition over the next 48 hours.  Most of the guidance models bring this to minimal hurricane status, just prior to hitting the more unfavorable conditions by day 5 – 7.  While I’m skeptical of this (initialization stage), with the models not developing this much, this is a slim probability right now, although should be considered low confidence right now.  The NHC has designated a
HIGH (90%) probability for cyclone development during the next 5 days.

WIND SHEAR FORECAST


500 MB RELATIVE HUMIDITY FORECAST

The disturbance is currently moving toward the west at 25 mph, and as of 12Z it was located near 10.2N;20.3W.  Maximum winds were 30 mph, and pressure was estimated to be 1009 mb or 29.79 in.

Based on analysis of forecast steering layers, and current model guidance, INVEST 95L should continue a general westward motion during the next 48 hours, before moving on a more north of due west path, and then to the WNW at around 72 hours in the period.  This will all depend on how quickly the system becomes organized and how strong it becomes.  Again, things can change, given this is all in the initialization stage.
ATCF 12Z GUIDANCE

NHC SPAGHETTI PLOT

I will continue to monitor this system during the next 48 – 96 hours for any significant changes.

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

 

 

 

palmharborforecastcenter

2021-09-14 18:44:38

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