Tropical Storm Isaac Entering Gulf: Track Still into La/Ms; Florida Panhandle Still At Risk

By: National Hurricane Center (NHC) with remarks by Oscar Fann WTVY-TV meteorologist
By: National Hurricane Center (NHC) with remarks by Oscar Fann WTVY-TV meteorologist

Tropical Storm Isaac Intermediate Advisory Number 23a
Nws National Hurricane Center Miami Fl
800 Pm Edt Sun Aug 26 2012

Summary Of 800 Pm Edt...0000 Utc...Information
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Location...24.1n 82.6w
About 60 Mi...100 Km Sw Of Key West Florida
About 530 Mi...850 Km Se Of The Mouth Of The Mississippi River
Maximum Sustained Winds...65 Mph...100 Km/H
Present Movement...Wnw Or 290 Degrees At 15 Mph...24 Km/H
Minimum Central Pressure...991 Mb...29.26 Inches

Watches And Warnings
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Changes With This Advisory...

None

Summary Of Watches And Warnings In Effect...

A Hurricane Warning Is In Effect For...
* East Of Morgan City Louisiana To Destin Florida...Including
Metropolitan New Orleans...Lake Pontchartrain...And Lake Maurepas

A Hurricane Watch Is In Effect For...
* East Of Destin To Indian Pass Florida

A Tropical Storm Warning Is In Effect For...
* The Florida Peninsula From Sebastian Inlet Southward On The East
Coast And From Tarpon Springs Southward On The West Coast.
* Florida Keys...Including The Dry Tortugas And Florida Bay
* Lake Okeechobee
* East Of Destin Florida To The Suwannee River

A Hurricane Warning Means That Hurricane Conditions Are Expected
Somewhere Within The Warning Area. A Warning Is Typically Issued
36 Hours Before The Anticipated First Occurrence Of
Tropical-Storm-Force Winds...Conditions That Make Outside
Preparations Difficult Or Dangerous. Preparations To Protect Life
And Property Should Be Rushed To Completion.

A Hurricane Watch Means That Hurricane Conditions Are Possible
Within The Watch Area. A Watch Is Typically Issued 48 Hours
Before The Anticipated First Occurrence Of Tropical-Storm-Force
Winds...Conditions That Make Outside Preparations Difficult Or
Dangerous.

A Tropical Storm Warning Means That Tropical Storm Conditions Are
Expected Somewhere Within The Warning Area Within 36 Hours.

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 48-Hour Outlook
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At 800 Pm Edt...0000 Utc...The Center Of Tropical Storm Isaac Was
Located Near Latitude 24.1 North...Longitude 82.6 West.

Isaac Is Moving Toward The West-Northwest Near 15 Mph...24 Km/H...And A Gradual Turn Toward The Northwest With A Decrease In Forward Speed Is Expected Over The Next 48 Hours.

On The Forecast Track...The Center Is Expected To Move Away From The Florida Keys Tonight...Move Over The Eastern Gulf Of Mexico On Monday...And Approach The Northern Gulf Coast On Tuesday.

Maximum Sustained Winds Are Near 65 Mph...100 Km/H...With Higher
Gusts.

Some Strengthening Is Forecast During The Next 48 Hours...And Isaac Is Expected To Become A Hurricane In A Day Or Two.

Tropical Storm Force Winds Extend Outward Up To 205 Miles...335 Km From The Center.

The Estimated Minimum Central Pressure Based On Noaa Hurricane
Hunter Data Is 991 Mb...29.26 Inches.

Hazards Affecting Land
----------------------
Rainfall...Total Rainfall Accumulations Of 4 To 7 Inches...With
Maximum Amounts Of 10 Inches...Are Possible Across The Florida
Keys And The Southern Half Of The Florida Peninsula. Total
Rainfall Amounts Of 5 To 10 Inches...With Maximum Amounts Of 15
Inches...Are Possible Along The Eastern And Central Gulf Coast.

Wind...Tropical Storm Conditions Are Occurring Over Portions Of
Southern Florida And The Florida Keys...And Should Spread Northward Along The Florida West Coast In The Tropical Storm Warning Area.

Tropical Storm Conditions Are Expected To Reach The Northern Gulf
Coast In The Warning Area By Late Monday...With Hurricane
Conditions Expected On Tuesday.

Storm Surge...The Combination Of A Storm Surge And The Tide Will
Cause Normally Dry Areas Near The Coast To Be Flooded By Rising
Waters. The Water Could Reach The Following Depths Above Ground If The Peak Surge Occurs At The Time Of High Tide...
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NOTE: WTVY-TV coastal residents please read
* Northern Gulf Coast Within The Hurricane Warning Area...6 To 12 Ft
* Remainder Of The Florida Panhandle And Apalachee Bay...4 To 7 Ft
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* Florida West Coast South Of Apalachee Bay...2 To 4 Ft
* Southeast Florida Coast And The Florida Keys...1 To 3 Ft
* Central And Western Cuba...1 To 3 Ft
* Northwestern Bahamas...1 To 3 Ft

The Deepest Water Will Occur Along The Immediate Coast In Areas Of Onshore Flow. 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 Weather Service Office. Near The
Coast...The Surge Will Be Accompanied By Large And Dangerous Waves.

Tornadoes...Isolated Tornadoes Are Possible Over Central And
Southern Florida Though Tonight.

Surf...Dangerous Surf And Rip Current Conditions Will Continue To
Affect The Northwestern Bahamas...Central Cuba...The Florida
Peninsula And The Florida Keys During The Next Day Or So. Please
Consult Products From Your Local Weather Office For More
Information.

Next Advisory
-------------
Next Complete Advisory...1100 Pm Edt.

Forecaster Brown/Blake

_____________________________________________________

Tropical Storm Isaac Discussion Number 23
Nws National Hurricane Center Miami Fl
500 Pm Edt Sun Aug 26 2012

Although Satellite And Radar Images Have Suggested That The Tropical Cyclone Was Becoming A Little Better Organized...An Air Force Hurricane Hunter Aircraft Investigating Isaac This Afternoon Have Found That There Has Been No Strengthening Of The Storm.

Flight-Level And Sfmr-Observed Winds Support An Intensity Of 50 Kt.

There Is Still A Well-Established Upper-Level Outflow Pattern Over
The System...And Vertical Shear Should Remain Fairly Light For The
Next Couple Of Days.

Intensification Still Seems Likely As Isaac Moves Over The Eastern Gulf...And Possibly Over The Higher Heat Content Of The Loop Current. The Official Intensity Foreast Is Close To The Latest Lgem Guidance...And Not Much Different From The Previous Nhc Forecast.

Isaac Has Moved A Little To The Left Of Previous Projections And
Center Fixes Yield A 6- To 12-Hour Averaged Motion Of 295/15.

The Track Forecast Continues To Be Challenging. The Dynamical Models Show The Tropical Storm/Hurricane Gradually Turning To The Right And Heading For A Break In The Subtropical Ridge.

However...There Are Substantial Differences Among The Most Reliable Models As To Where Isaac Might Cross The Northern Gulf Coast.

The U.K. Met. Office And Ecmwf Models Are About 300 N Mi To The East Of The Gfs At Landfall. It Should Be Noted That Nearly All Of The Gfs Ensmeble Members Are East Of The Gfs Control Track. Because Of The Wide Model Spread...There Continues To Be Greater Than Usual Track Forecast Uncertainty.

Throughout The Period...It Is Important Not To Focus On The Exact
Forecast Track Due To Forecast Uncertainties And The Fact That
Significant Hazards Extend Well Away From The Center.

The Official Forecast Track And Wind Radii Necessitate The Issuance
Of A Hurricane Warning For The Northern Gulf Coast At This Time.

Forecast Positions And Max Winds

Init 26/2100z 24.2n 82.3w 50 Kt 60 Mph
12h 27/0600z 25.1n 83.9w 55 Kt 65 Mph
24h 27/1800z 26.3n 85.9w 60 Kt 70 Mph
36h 28/0600z 27.7n 87.6w 70 Kt 80 Mph
48h 28/1800z 28.9n 88.5w 80 Kt 90 Mph
72h 29/1800z 30.7n 89.5w 85 Kt 100 Mph...Inland
96h 30/1800z 32.5n 90.0w 30 Kt 35 Mph...Inland
120h 31/1800z 34.5n 90.0w 20 Kt 25 Mph...Inland

Forecaster Pasch
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Oscar's remarks follow...

Let me clarify the watches and warnings for the Florida panhandle counties and coastline.

HURRICANE WARNING -
is in effect for Okaloosa county WESTWARD to Louisiana...
(this includes Destin and the coast to the WEST toward Louisiana)

HURRICANE WATCH -
is in effect for the Florida panhandle coast for south Walton and coastal Bay and coastal Gulf counties

TROPICAL STORM WARNING -
is in effect for the coast EAST of Destin through Apalachicola and for all of the Apalachee Bay area. INCLUDED are the counties of Walton, Holmes, Washington, Bay, Gulf, Franklin, Calhoun and Liberty.
(For now, Jackson and Gadsden counties are NOT in the tropical storm warning area).

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Now, comments on the forecast track of Isaac -

Isaac has indeed moved more westward today, and this helps put more credence into Isaac's future forecast path.

(UPDATE - the new 8pm edt Aug 26 Isaac update shows this basically westward motion is continuing for now)

I think this primarily westward movement we saw today (and is still occurring) bodes well for the forecast landfall area late Tuesday for either:

1) the Louisiana / Mississippi area (the National Hurricane Center's official landfall area; or

2) south of New Orleans along the southeast Louisiana coast then slowly westward along the Louisiana coast.

(NOTE: This is an even further westward placement for the landfall since this morning's initial westward shift)
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The two main concerns for the WTVY-TV area are:

1) storm surges and coastal flooding;

2) excessive rains and stream flooding.

The current landfall area of near the Ms/La border STILL HAS SIGNIFICANT implications for areas to the east, all the way through Mobile, Pensacola, Destin, Panama City, Apalachicola into the Apalachee Bay area (Carrabelle, St. George Island, Alligator Point).

These coastal areas face storm surges of 6 to 12 feet (from Destin westward) and 4-7 feet east of Destin.

These water levels are in addition to normal high and low tides..by the way, over the next few mornings, high tides are occurring around 6 to 10 am local time. This would be the time storm surges would have the most effect.

For now (with the La/Ms path) the heaviest rains will be consistently along and south of I-10 in the Florida panhandle.

Inland areas such as south central and southeast Alabama as well as southwestern Georgia could have excessive rains, but more of a sporadic nature (off and on torrential downpours).

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A REMINDER -

BE AWARE of old, large trees near where you live. The age of these trees with the dry weather earlier this summer may have weakened them..THEN the above average rainfalls this month may have loosened their root structure.

High winds (even only gusty winds to 30 - 40 mph) may be enough to topple such trees. Over the next several days, take note during the day of all such trees near your house to see if you notice any change in appearance, such as if there's more of a lean to them.

EXPECT POWER OUTAGES..hopefully they will be of a short term, isolated nature..regardless, don't be surprised if you lose power at some point through midweek, especially closer to the coast.

A TORNADO THREAT will exist beginning late Monday through at least part of Wednesday, but it's too early to be more specific on this, except the tornado threat will be higher in the Florida panhandle.

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MORE ON ISAAC's PATH...

If Isaac take the route to southeastern Louisiana then moves slowly west along the Louisiana coast, this would reduce many of our weather related concerns after Tuesday night.

We should know if the few holdout weather models (which try to take Isaac more northward to the Alabama / Florida border) will change their forecast after ingesting the new data showing Isaac took a more westward motion for most of the day today. A potential landfall say near Gulf Shores would change everything for the worse for all of us in the WTVY-TV area.

AGAIN, the Alabama / Florida landfall area is NOT the forecast path for Isaac. The trend for the last 24 to 48 hours has consistently been to either the La / Ms border area or to the Louisiana coast then westward.

I'll have another update later tonight. Keep your fingers crossed.

Oscar


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