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Severe Storms - North and Central Fla/S. Ga - Thu 4/4


SouthernNJ

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A few things are still unclear, but there is potential for severe thunderstorms

and a few tornadoes Thursday in the North and Central Florida/South Georgia

region. The SPC has added a 30% area for Day 2.  The advancement of the

warm front will be important as to how many tornadoes could potentially form.

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From JAX's afternoon discussion...

SHORT TERM /THURSDAY THROUGH FRIDAY/...

AS WE MOVE INTO THURSDAY...THE THREAT FOR SIGNIFICANT SEVERE

WEATHER WILL DEFINITELY BECOME A CONCERN. A WARM FRONT WILL BE

DRAPED ACROSS THE FORECAST AREA ROUGHLY NEAR AND PARALLEL TO THE

FLORIDA/GEORGIA BORDER. AT THE SAME TIME...A STRONG SURFACE HIGH

PRESSURE OVER THE MID ATLANTIC STATES WILL CREATE A WEDGE DOWN THE

EASTERN SEABOARD. THE WEDGE IS EXPECTED TO BE STRONG ENOUGH TO

KEEP THE WARM FRONT NEARLY STATIONARY ACROSS OUR AREA DURING THE

DAY AND INTO THE EVENING. THE WEDGE WILL ALSO LIKELY ACT TO INDUCE

SURFACE CYCLOGENESIS JUST OFFSHORE OF OUR ATLANTIC COAST WHICH

WILL ENHANCE THE BAROCLINIC ZONE AND LOW LEVEL CONVERGENCE ACROSS

OUR AREA DURING THE DAY...WHICH IS NOT TOO DISSIMILAR TO WHAT

HAPPENED IN OUR LAST EVENT ABOUT TWO WEEKS AGO.

STRONG FORCING WILL RESIDE ACROSS THE AREA ON THURSDAY AS WAVES

OF LOW PRESSURE MOVE EAST ALONG THE WARM FRONT IN CONCERT WITH

STRONG SHORTWAVE ENERGY WHICH WILL BE TRAVERSING THE AREA IN

ADVANCE OF A DEEPENING MID TO UPPER LEVEL CLOSED LOW. LIMITED

SURFACE DESTABILIZATION DUE TO CLOUDS/PRECIP WILL BE COMPENSATED

BY STEEPENING MID LEVEL LAPSE RATES AND SHEAR PROFILES STRONG

ENOUGH TO SUPPORT THE POTENTIAL FOR SEVERE THUNDERSTORMS. DAMAGING

WIND GUSTS...LARGE HAIL...AND VERY HEAVY RAINFALL WILL BE THE MAIN

CONCERNS...BUT IT SHOULD BE NOTED THAT SIMILAR WEATHER PATTERNS IN

THE PAST HAVE SPAWNED TORNADOES...SO ISOLATED TORNADOES WILL BE

POSSIBLE NEAR THE WARM FRONT PARTICULARLY IF WE ARE SOMEHOW ABLE

TO INCREASE SURFACE INSTABILITY. THE MAIN SEVERE THREAT WILL BE

ALONG AND SOUTH OF THE WARM FRONT WHICH WILL PRIMARILY BE ACROSS

NORTHEAST FLORIDA THURSDAY AFTERNOON INTO THE EVENING.

TEMPERATURES WILL RANGE FROM THE 60S NORTH OF THE WARM FRONT TO

NEAR 80 ACROSS OUR SOUTHERN ZONES.

IT SHOULD BE NOTED THAT THIS IS AN EXTREMELY CHALLENGING FORECAST

AND THERE REMAINS A LARGE SPREAD AMONGST THE MODELS AS TO JUST

HOW FAR NORTH THE WARM FRONT LIFTS TOMORROW. WE ARE FAVORING THE

NAM SOLUTION BASED ON ITS HISTORICAL ADVANTAGE OF HANDLING THESE

WEDGE TYPE PATTERNS DOWN THE EAST COAST.

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So they went with the NAM out of all models but they did have a good reason for that. SPC took us out the threat here. That quickly made me lose interest in this event. Pretty exciting though if you live in N FL which is only about 1 member on here (pcbrq).

Oh, it was always gonna be nothing but Wedge City up here. But watching the radar might be fun tomorrow :P

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I'd rather avoid any severe weather on the 8th floor of a resort building here in Kissimmee.

 

Heavy rain this afternoon/evening in the area.  Lots of urban flooding in the streets.  I find it humorous that lawn sprinklers are running when an inch or two of rain is in the midst of falling and the streets have 3+ inches of water on them.  I know...timers...but still.

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Interesting to see that my area is in a 10% risk for tornadoes today. I don't recall the last time I saw that locally (outside of a tropical system enhanced tornado threat). Of course the bar for severe weather in C. FL for me will always be 2/22/98 but I've never been able to find a graphic from SPC on what level risk they had that day.

 

I have a 6th floor, southwest facing view today for the show, assuming anything develops locally. :popcorn:

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Mesoscale Discussion 385

< Previous MD

mcd0385.gif


MESOSCALE DISCUSSION 0385

NWS STORM PREDICTION CENTER NORMAN OK

0908 AM CDT THU APR 04 2013

AREAS AFFECTED...SCNTRL FL

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 041408Z - 041515Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...THREAT FOR DAMAGING WIND AND ISOLATED TORNADOES IS

EXPECTED TO INCREASE THIS MORNING AND INTO THE AFTERNOON AS STORMS

MOVE INLAND NEAR AND SOUTH OF THE TAMPA BAY AREA. OTHER STORMS MAY

DEVELOP OVER S FL. A WW WILL LIKELY BE NEEDED SOON.

DISCUSSION...THIS MORNING A STATIONARY E-W ORIENTED OUTFLOW BOUNDARY

WITH ACTIVE CONVECTION EXTENDS FROM NEAR TAMPA THROUGH CNTRL FL. A

MOIST WARM SECTOR EXISTS SOUTH OF THIS BOUNDARY WITH DEWPOINTS

GENERALLY IN THE UPPER 60S...AND VISIBLE SATELLITE IMAGERY SHOWS

NUMEROUS BREAKS SUGGESTING THE BOUNDARY LAYER WILL CONTINUE TO

DESTABILIZE AS DIABATIC WARMING COMMENCES. THE MIAMI SOUNDING

INDICATED A SOMEWHAT SHALLOW BOUNDARY LAYER...AND DEWPOINTS COULD

MIX DOWN SLIGHTLY AS HEATING COMMENCES...BUT AT LEAST MID 60S SHOULD

BE REPRESENTATIVE WITH MLCAPE AROUND 1500-2000 J/KG AS TEMPERATURES

WARM INTO THE 80S. VWP DATA INDICATE DEEP SHEAR FROM 30-35 KT OVER

CNTRL FL. THOUGH 0-1 KM HODOGRAPHS ARE NOT PARTICULARLY

LARGE...VEERING LOW LEVEL PROFILES EXIST...AND STORMS MAY ALSO

INTERACT WITH E-W ORIENTED BOUNDARY ACROSS CNTRL FL...POSSIBLY

AUGMENTING THREAT FOR ISOLATED TORNADOES. LINE OF STORMS JUST OFF

THE WEST COAST OF FL ALREADY SHOWS ORGANIZED STRUCTURES WITH

EMBEDDED SUPERCELLS. OTHER STORMS MAY DEVELOP ACROSS S FL IN

ASSOCIATION WITH SEA-BREEZE CIRCULATIONS WHERE THE ATMOSPHERE IS

MORE UNSTABLE AND DEEP SHEAR AROUND 45-50 KT IS SUPPORTIVE OF

SUPERCELLS.

..DIAL/CORFIDI.. 04/04/2013

ATTN...WFO...MFL...MLB...TBW...

LAT...LON 27608257 27668176 27878053 26828012 25718048 26448191

27608257

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Interesting to see that my area is in a 10% risk for tornadoes today. I don't recall the last time I saw that locally (outside of a tropical system enhanced tornado threat). Of course the bar for severe weather in C. FL for me will always be 2/22/98 but I've never been able to find a graphic from SPC on what level risk they had that day.

 

You may have seen this before, but this is a great page with lots of information on the 1998 outbreak: http://www.srh.noaa.gov/mlb/?n=022398

 

They don't have a graphic of the SPC outlooks issued before the outbreak, but according to the service assessment, Central FL was under Moderate Risk with the threat of long-lived supercells and tornadoes mentioned.

 

Here is a compilation of warning and advisory products issued by NWS MLB during the event: http://www.srh.noaa.gov/media/mlb/pdfs/mlbsep_outbreak98.pdf

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From NWS Miami's morning discussion...

 

WATER VAPOR IMAGERY AND NAM ANALYSIS SHOWED AN UPPER LEVEL LOWDIGGING ACROSS NORTHEAST TEXAS AND SOUTHERN OKLAHOMA...WITH ASURFACE LOW TAKING SHAPE ACROSS THE NORTH CENTRAL GULF. GUIDANCE ISINDICATING THAT ONE OF THE TWO MCS FEATURES ACROSS THE EASTERN GULFWILL MAKE ITS WAY TOWARDS SOUTH FLORIDA BY EARLYAFTERNOON...WEAKENING AS IT MOVES ONSHORE THE GULF COAST NEARNAPLES. HOWEVER...WITH THE MCS COMING IN NEAR PEAKHEATING...SUFFICIENT INSTABILITY...WEAK WARM AIR ADVECTION ALONGWITH 0-1KM BULK SHEAR OF 20 KNOTS AND 0-6KM BULK SHEAR VALUES OF40-45 KNOTS SHOULD SUPPORT ROTATING UPDRAFTS. 0-1KM HELICITY VALUESARE EXPECTED TO BE GREATER THAN 100 M^2/S^2 NORTH OF LINE NEAR WESTPALM BEACH TO THE COLLIER/MAINLAND MONROE BORDER...WITH VALUESAROUND 150 M^2/S^2 ACROSS GLADES COUNTY. WITH SURFACE BASED CAPE OF1500-2200 J/KG AND STEEP LOW/MID LEVEL LAPSE RATES...THE MAINTHREATS WILL BE SUPERCELL THUNDERSTORMS CAPABLE OF PRODUCINGSTRAIGHT LINE WINDS IN EXCESS OF 60 MPH AND LARGE HAIL UP TO GOLFBALL SIZE. WITH THE LARGE HELICITY VALUES ISOLATED TORNADOES ARENOT OUT OF THE QUESTION. THE LOCATIONS WITH THE GREATEST THREATTODAY IS EXPECTED TO BE THE INTERIOR AND THE LAKE REGION. ALIMITING FACTOR COULD BE CLOUD COVER OUT AHEAD OF THE MCS...BUTWITH TEMPERATURES ALREADY STARTING OUT NEAR 70 TO THE LOWER70S...THEY SHOULD BE ABLE TO QUICKLY GET INTO AT LEAST THE LOWER80S.THE 00Z GFS IS A LITTLE FURTHER EAST WITH THE SURFACE LOW THAN THEPREVIOUS RUN...MOVING IT INTO NORTH FLORIDA/SOUTHERN GEORGIA BY 00ZTHIS EVENING. THE UPPER LEVEL LOW WILL MOVE EAST INTOALABAMA/WESTERN GEORGIA...WITH THE SURFACE LOW WILL MOVING OUT INTOTHE WESTERN ATLANTIC AND RACING UP THE EAST COAST OVERNIGHT. MODELSARE IN GOOD AGREEMENT WITH THE OVERALL TIMING OF THE SQUALL LINEALONG THE COLD FRONT...WITH THE LINE OF STORMS MOVING INTO THE LAKEREGION LATE IN THE NIGHT INTO FRIDAY MORNING AND THEN THROUGH THEREST OF THE REGION BY THE MID/LATE AFTERNOON. SOUTH FLORIDA WILLBE IN THE RIGHT ENTRANCE REGION OF THE 110KT 250MB JET STREAK LATETONIGHT THROUGH THE DAY ON FRIDAY. WINDS WILL BECOME MOREUNIDIRECTIONAL TONIGHT INTO FRIDAY...BUT 0-6KM BULK SHEAR VALUESWILL INCREASE TO 45-60KT. SO A SQUALL LINE LATE TONIGHT INTOFRIDAY MORNING IS EXPECTED NEAR THE LAKE DUE TO FRONTAL FORCINGAND STRONG DEEP LAYER SHEER...WITH THE MAIN THREAT BEING DAMAGINGWINDS IN EXCESS OF 60 MPH. THE SITUATION BECOMES MORE COMPLEX LATEFRIDAY MORNING INTO THE AFTERNOON AS ANY DIURNAL HEATING AND WARMAIR ADVECTION COULD CAUSE MULTIPLE STORM MODES. SO SEVERE STORMSWILL BE POSSIBLE THROUGH THE DAY FRIDAY UNTIL THE FRONT PASSESTHROUGH. DAMAGING WINDS AND LARGE HAIL WILL ONCE AGAIN BE THE MAINTHREATS...ESPECIALLY FOR THE EAST COAST METRO AREAS. WIDESPREAD1-2 INCHES OF RAIN IS LIKELY FROM THIS EVENT ACROSS THEREGION...WITH ISOLATED HIGHER AMOUNTS.
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You may have seen this before, but this is a great page with lots of information on the 1998 outbreak: http://www.srh.noaa.gov/mlb/?n=022398

They don't have a graphic of the SPC outlooks issued before the outbreak, but according to the service assessment, Central FL was under Moderate Risk with the threat of long-lived supercells and tornadoes mentioned.

Here is a compilation of warning and advisory products issued by NWS MLB during the event: http://www.srh.noaa.gov/media/mlb/pdfs/mlbsep_outbreak98.pdf

Thanks for the link! I had seen the compilation of adivisory products previously but somehow missed the SPC info. Definitely my most personal encounter with severe weather as I lived about 5 miles south of the Winter Garden supercell at the time.

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Tornado Warning


TORNADO WARNING

FLC027-049-041830-

/O.NEW.KTBW.TO.W.0001.130404T1750Z-130404T1830Z/

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL

150 PM EDT THU APR 4 2013

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED A

* TORNADO WARNING FOR...

SOUTHERN HARDEE COUNTY IN FLORIDA.

DESOTO COUNTY IN FLORIDA.

* UNTIL 230 PM EDT

* AT 149 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

TORNADO NEAR FORT OGDEN...OR 7 MILES SOUTHWEST OF ARCADIA...MOVING

NORTHEAST AT 30 MPH.

* THE TORNADO WILL BE NEAR...

FORT OGDEN.

ARCADIA.

SWEETWATER.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IF YOU ARE IN THE PATH OF THE TORNADO GO TO A SMALL INTERIOR ROOM IN

A STRONG AND WELL CONSTRUCTED BUILDING. CARS AND MOBILE HOMES ARE NOT

SAFE. IF NO SHELTER IS AVAILABLE...LIE FLAT IN A DITCH OR CULVERT AND

COVER YOUR HEAD WITH YOUR HANDS.

TO REPORT SEVERE WEATHER TO THE NATIONAL WEATHER SERVICE PLEASE CALL

813-645-2323.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 800 PM EDT THURSDAY EVENING

FOR SOUTHWESTERN FLORIDA.

&&

LAT...LON 2743 8169 2728 8157 2706 8197 2713 8203

TIME...MOT...LOC 1750Z 234DEG 25KT 2715 8192

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THE NATIONAL WEATHER SERVICE IN MELBOURNE HAS ISSUED A

* TORNADO WARNING FOR...

EASTERN MARTIN COUNTY IN FLORIDA...

THIS INCLUDES THE CITIES OF...PORT SALERNO...JUPITER ISLAND...HOBE

SOUND...

* UNTIL 415 PM EDT.

* AT 306 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A

SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 17 MILES WEST OF

JONATHAN DICKINSON STATE PARK...OR 7 MILES SOUTHEAST OF

INDIANTOWN...MOVING NORTHEAST AT 20 MPH.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO

WITHAM FIELD...HOBE SOUND BEACH AND SEWALLS POINT

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Appears the 2nd squall line is ahead of schedule as its already forming WSW of Tampa. I'm curious about the outflow orientation currently being to the ENE and whether the expected transition of the upper level support to a NNE flow will allow the line to build further north. In any event, the dynamics appear a bit more potent with this second round.

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