Strong Wind in Alabama, February 18, 2013

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
712 PM CST MON FEB 18 2013

.UPDATE...
TO EXPAND A WIND ADVISORY FOR THE REMAINDER OF OUR FORECAST AREA (IN
NWRN AL). ALSO TO LOWER EVENING POPS IN EASTERN PORTIONS OF THE
FORECAST AREA.

&&

.DISCUSSION...
WE HAVE LOWERED PRE-06Z POPS FROM CATEGORICAL LEVELS, MAINLY ACROSS
EASTERN PORTIONS OF THE FORECAST AREA. THE LEADING EDGE OF THE
INITIAL BAND OF SHRA WAS JUST CLIPPING THE NW TIP OF AL. THE QLCS IN
AR WAS PRESENTING SEVERAL NOTABLE LEWPS AND BOWS, AND WAS MAKING
RAPID PROGRESS EWD AROUND 45KT. THE QLCS WILL CROSS THE MS RIVER
WITHIN THE HR. AT IT'S PRESENT SPEED, IT SHOULD REACH NWRN AL BETWEEN
04-06Z IF NOT A BIT SOONER. THE LINE SHOULD WEAKEN GIVEN THE LACK OF
INSTABILITY AND LOW LEVEL MOISTURE OVER THE TN VALLEY, BUT COULD
STILL PRODUCE HIGHER GUSTS WITH THE PRESENCE OF THE STRONG LOW LEVEL
WIND FIELD. WITH SITES ALREADY FLIRTING NEAR THE 35 MPH GUST
THRESHOLD FOR A WIND ADVISORY, WILL GO AHEAD AND EXPAND OUR CURRENT
ADVISORY FOR ALL COUNTIES. SHRA ACTIVITY ENTERING NWRN AL MAY
OVERTURN SOME OF THE MOMENTUM GENERATED BY THE LLJ THAT IS
ACCELERATING JUST ABOVE THE SFC LAYER.

AK

&&

.AVIATION...
/ISSUED 458 PM CST MON FEB 18 2013/
FOR 00Z TAFS... GUSTY SOUTHERLY WINDS WILL OCCUR THIS EVENING IN
ADVANCE OF A STRONG COLD FRONT. LLWS WILL DEVELOP JUST AHEAD OF THE
FRONT AS WELL. CONDS SHOULD REMAIN PRIMARILY VFR BEFORE A PRE-FRONTAL
SQLN OF SHRA AND TSRA ARRIVES, WHEN PERIODIC LOWER VSBY IN THE MVFR
RANGE IS XPCTD. CIGS MAY REMAIN AOA 030AGL, ALTHOUGH BRIEF LOWERING
INTO MVFR RANGE IS PSBL. GUSTY WINDS DURG THE STORMS IS ALSO PSBL,
BUT HAVE NOT ADDED THIS TO THE TAFS JUST YET, BUT AMDS MAY BE
REQUIRED LATER THIS EVENING. FROPA IS ANTICIPATED SHORTLY AFTER THE
RAIN ENDS (~11Z AT KMSL AND ~13Z AT KHSV). GUSTY NWLY WINDS SHOULD
OCCUR ON TUESDAY BEHIND THE FRONT WITH VFR CONDS XPCTD.

AK

&&

.PREV DISCUSSION...
/ISSUED 346 PM CST MON FEB 18 2013/
THIS AFTERNOON A COLD FRONT EXTENDS FROM A LOW PRESSURE CENTER OVER
NORTHERN MO SOUTHWEST TOWARD CENTRAL TX. IN THE REGION OF STRONGEST
MOISTURE ADVECTION AHEAD OF THE FRONT...PRECIP EXTENDS AS FAR EAST
AS WESTERN TN/KY AND NORTHERN MS. IN THESE LOCATIONS...DEWPOINTS HAVE
SURGED BACK INTO THE MID 40S TO LOW 50S...WHILE FURTHER EAST OVER
MUCH OF AL AND CENTRAL TN DEWPOINTS ARE STILL IN THE LOWER/MID 30S.
WINDS ACROSS MUCH OF THE SOUTHEAST HAVE BEEN GUSTY THROUGH THE
AFTERNOON AS WELL...WITH GUSTS IN OUR CWA RANGING FROM THE MID 20S TO
LOWER 30S FOR MUCH OF THE DAY.

AS THE COLD FRONT SWINGS ACROSS THE AREA TONIGHT...THE LL JET WILL
INCREASE SIGNIFICANTLY OVER N AL AND NORTHWARD ACROSS THE OHIO
VALLEY. 850MB WINDS AT 18Z OVER CENTRAL ARK WERE OVER 50KTS...AND
THESE SPEEDS SHOULD INCREASE TO BTWN 55KTS IN OUR AREA TO MORE LIKE
70KTS WELL TO OUR N BY 06Z AS IT SHIFTS EASTWARD. THE NOCTURNAL
INVERSION THAT WILL SETUP AFTER SUNSET WILL HELP PREVENT THE
STRONGEST WINDS FROM EXTENDING DOWN TO THE SFC...BUT A MARKED
INCREASE IN WINDS (PER MODEL SOUNDINGS) CAN BE EXPECTED JUST OFF THE
DECK (BY ABT 1000-1500FT). CONSIDERING THAT GUSTS HAVE HOVERED AROUND
30MPH ACROSS A GOOD PORTION OF THE CWA ALREADY THIS AFTERNOON...DO
NOT EXPECT IT TO BE A CHALLENGE FOR HIGHER TERRAIN LOCATIONS OF THE
CWA TO REACH WIND ADVISORY CRITERIA AS THE LL JET PICKS UP SPEED AND
CROSSES THE CWA. HAVE THEREFORE ISSUED A WIND ADVISORY FOR COUNTIES
WITH HIGHER TERRAIN...WITH THE BIGGEST THREAT EXPECTED FOR THE HIGH
ELEVATIONS IN JACKSON CO AL/FRANKLIN CO TN. ANY STRONGER SHOWERS OR
T-STORMS THAT PROGRESS ALONG AND AHEAD OF THE FRONT COULD ALSO DRAW
SOME OF THESE STRONGER WINDS DOWN TO THE SFC...BUT THE INVERSION
SHOULD PREVENT WIDESPREAD PROBLEMS. CONDITIONS SHOULD BEGIN TO
IMPROVE RAPIDLY AFTER 09Z AS THE FRONT PUSHES EAST OF THE CWA.

OUR NEXT FRONT SHOULD ARRIVE THURSDAY NIGHT/FRIDAY AND BRING ANOTHER
ROUND OF SHOWERS AND THUNDERSTORMS. INSTABILITY SHOULD REMAIN LIMITED
IN OUR CWA WITH THIS SYSTEM AS WE WILL ONLY SEE A SHORT BURST OF
RETURN FLOW THURSDAY AFTERNOON JUST AHEAD OF THE FRONT. HIGH PRESSURE
SLIDING VERY SLOWLY ACROSS THE OHIO VALLEY WILL KEEP FLOW NORTHERLY
FOR MUCH OF WEDNESDAY AND PREVENT DEWPOINTS PREDOMINANTLY IN THE
TEENS UNTIL THURSDAY AFTERNOON. EVEN WITH THE LIMITED
INSTABILITY...WINDS WINDS INCREASE AGAIN ALONG AND AHEAD OF THE
FRONT. ATTM IT LOOKS LIKE WINDS WILL BE LESS INTENSE WITH THIS NEXT
SYSTEM...BUT THEY WILL BEAR MONITORING.

THE DRIVING LOW PRESSURE SYSTEM FOR THIS FRONT TRACKS WELL TO THE N
ON FRIDAY AND GETS WRAPPED BACK INTO THE MAIN TROF AS ANOTHER PIECE
OF ENERGY SWINGS DOWN ACROSS THE ROCKIES...DEEPENING THE TROF AND
PROVIDING MORE EASTWARD MOMENTUM. THIS WILL CAUSE THE INITIAL FRONT
TO LOSE SPEED AS IT TRACKS ACROSS THE SOUTHEAST...STALLING SLIGHTLY
TO OUR SE BEFORE THE SECOND SHORTWAVE PUSHES OUT OF THE SW. THIS
COULD LEAD TO A BRIEF BREAK IN POPS FOR OUR CWA (WHILE S/CENTRAL
PORTIONS OF MS/AL/GA SEE CONTINUED RAIN) AND THEN ANOTHER QUICK SHOT
OF RAIN FRIDAY NIGHT. AM NOT COMPLETELY CONVINCED THE ENTIRE CWA WILL
SEE A BREAK IN THE RAIN...BUT HAVE TRIMMED POPS DOWN IN THE
NORTHERN/WESTERN PORTIONS OF THE CWA FOR LATE FRIDAY AFTERNOON/EARLY
EVENING.

HEADING INTO EARLY NEXT WEEK...THE FORECAST BECOMES FAIRLY MURKY WITH
SIGNIFICANT TIMING DIFFERENCES BETWEEN THE MAJOR GLOBAL MODELS IN
TERMS OF THE NEXT TROF PROGRESSION. THE GFS MOVES THE NEXT SYSTEM
THROUGH MONDAY WHILE THE ECWMF OUTPUT LAGS BY ABOUT A DAY. HAVE
THEREFORE NOT MADE ANY SIGNIFICANT CHANGES TO THE FAR EXTENDED AND
JUST STARTED INTRODUCING SLT CHC / CHC POPS ON MONDAY...SINCE THE GFS
SOLN SEEMS TO BE MORE IN KEEPING WITH RECENT PROGRESSIVE TRENDS.

CCC

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...WIND ADVISORY UNTIL 3 AM CST TUESDAY FOR ALZ001>010-016.

TN...WIND ADVISORY UNTIL 3 AM CST TUESDAY FOR TNZ076-096-097.

&&

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE
AT WEATHER.GOV/HUNTSVILLE.

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
748 PM CST MON FEB 18 2013

ALZ001>010-016-TNZ076-096-097-191100-
LAUDERDALE-COLBERT-FRANKLIN AL-LAWRENCE-LIMESTONE-MADISON-MORGAN-
MARSHALL-JACKSON-DEKALB-CULLMAN-MOORE-LINCOLN-FRANKLIN TN-
748 PM CST MON FEB 18 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH ALABAMA AND PORTIONS
OF SOUTHERN MIDDLE TENNESSEE.

.DAY ONE...TONIGHT...

WINDY CONDITIONS WILL PERSIST THIS EVENING INTO THE OVERNIGHT HOURS
IN ADVANCE OF A STRONG COLD FRONT. SUSTAINED WINDS OF 15 TO 30 MPH
WILL BE COMMON...WITH GUSTS AROUND 35 MPH. IN THE HIGHER ELEVATIONS
OF NORTHEAST ALABAMA AND SOUTHERN MIDDLE TENNESSEE...GUSTS ABOVE 40
MPH WILL DEVELOP...ESPECIALLY BETWEEN 9 PM AND 3 AM.

SHOWERS AND A FEW THUNDERSTORMS WILL MOVE INTO NORTHWEST ALABAMA
BETWEEN 9 AM AND MIDNIGHT...THEN TRACK EASTWARD ACROSS THE REST OF
THE TENNESSEE VALLEY BETWEEN MIDNIGHT AND 4 AM. A FEW SHOWERS OR
STORMS MAY PRODUCE BRIEF WIND GUSTS UP TO 50 MPH.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY...

WINDY CONDITIONS WILL REDEVELOP ON THURSDAY AHEAD OF AN APPROACHING
STORM SYSTEM AND COLD FRONT. IN ADDITION...ANOTHER ROUND OF SHOWERS
AND ISOLATED THUNDERSTORMS WILL MOVE INTO THE REGION THURSDAY THROUGH
EARLY FRIDAY. STRONG GUSTY WINDS ARE POSSIBLE WITHIN A FEW
STORMS...BUT THE OVERALL CHANCE FOR SEVERE WEATHER APPEARS LIMITED.

.SPOTTER CALL TO ACTION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT PERSONNEL IS
NOT ANTICIPATED AT THIS TIME.