Wildfire in Alabama, March 18 to 22, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1007 PM CDT SAT MAR 17 2012

.UPDATE...
EVENING UPDATE TO PUBLIC FORECAST.

&&

.DISCUSSION...
BASED ON LATEST TRENDS IN WSR-88D DATA...HAVE DECIDED TO ADJUST POPS
FOR THE REMAINDER OF THE OVERNIGHT HOURS TO LEAVE A SLIGHT CHANCE
OF SHOWERS/THUNDERSTORMS IN PLACE ACROSS THE SOUTHERN MIDDLE
TENNESSEE COUNTIES...WHERE STRONGEST/DEEPEST ASCENT ASSOCIATED WITH A
MID-LEVEL DISTURBANCE PASSING TO THE NORTH OF THE AREA WILL BE
LOCATED. OTHERWISE...WILL ONLY BE MAKING MINOR ADJUSTMENTS TO HOURLY
WIND/TEMPERATURE/DEW POINT GRIDS TO REFLECT CURRENT OBSERVATIONS...
AND SKY COVER GRIDS TO INDICATE A MORE RAPID CLEARING TREND FROM THE
WEST AS SEEN IN THE LATEST 11-3.9 MICRON SATELLITE DATA. UPDATED
PRODUCTS WILL BE ISSUED SHORTLY.

70/DD

&&

.AVIATION...
/ISSUED 711 PM CDT SAT MAR 17 2012/
FOR 00Z TAFS...VFR CONDS WILL PREVAIL AT BOTH HSV/MSL THRU THE VALID
TAF PERIOD...WITH DECKS OF SCT AC AND BKN CI EXPECTED TO DIMINISH
OVERNIGHT. SURFACE WINDS WILL TRANSITION FROM LIGHT SSW TO LGT/VRB
OVERNIGHT...AND SKIES MAY CLEAR SUFFICIENTLY FOR THE DEVELOPMENT OF
LIGHT BR AT BOTH TERMINALS DURING A 3-HOUR WINDOW BTWN 18/10-13Z.
HOWEVER...LINGERING/RESIDUAL CLOUD COVER WILL LIKELY PREVENT VSBY
FROM DROPPING MORE THAN CURRENTLY FORECAST. AN UPPER-LEVEL RIDGE
DEVELOPING OVER THE REGION TOMORROW WILL ENSURE PRECIP CHANCES TOO
LOW TO MENTION IN THE FORECAST...WITH FEW CU/SCT CI AND A SSW WIND AT
5-10 KNOTS EXPECTED THRU EARLY SUNDAY EVENING.

70/DD

&&

.PREV DISCUSSION...
/ISSUED 209 PM CDT SAT MAR 17 2012/
THE 19Z SURFACE ANALYSIS INDICATES THAT A WEAK BOUNDARY ACROSS WEST
TENNESSEE IS THE FOCUSING MECHANISM FOR SHOWER AND THUNDERSTORM
DEVELOPMENT ACROSS PORTIONS OF MIDDLE TENNESSEE AND INTO NORTH
ALABAMA. WILL CONTINUE WITH A SLIGHT CHANCE POP TO ACCOUNT FOR THE
WIDELY SCATTERED SHOWERS AND THUNDERSTORMS THAT ARE EXPECTED TO
CONTINUE UNTIL AROUND 00Z.

THE MID TO UPPER LEVEL RIDGE OF HIGH PRESSURE IS THEN EXPECTED TO
BUILD MORE INTO THE FORECAST AREA FOR SUNDAY THROUGH TUESDAY. ALL OF
THE MODELS REMAIN CONSISTENT IN BUILDING THE STRONG RIDGE OVER THE
EASTERN HALF OF THE COUNTRY. WITH THE LOW LEVEL SOUTHERLY FLOW
EXPECTED...TEMPS WILL CONTINUE TO RUN AT AROUND 20 DEGREES ABOVE
NORMAL FOR DAYTIME HIGHS. THE GOOD DIURNAL TEMP RANGE FOR OVERNIGHT
LOWS ALSO LOOKS GOOD...AND HAVE GENERALLY ACCEPTED A CLOSE MIX
BETWEEN THE GFS AND NAM FORECAST NUMBERS THROUGH TUESDAY. SINCE WE
WILL BE CLOSE TO RECORD HIGHS THROUGH THE PERIOD...HERE ARE THE HIGH
TEMP RECORDS THROUGH MARCH 20TH.

HSV RECORD HIGHS...
MARCH 18...87 (1908)
MARCH 19...84 (1982)
MARCH 20...86 (2004)

MSL RECORD HIGHS...
MARCH 18...87 (1908)
MARCH 19...88 (1912)
MARCH 20...88 (1907)

THE SURFACE THROUGH UPPER RIDGE WILL BE HARD TO BREAK UNTIL MID NEXT
WEEK AS AN UPPER TROUGH AND LOW PRESSURE ACROSS THE SOUTHWEST U.S. IS
PROGGED TO MOVE SLOWLY EAST AND NORTHEAST WITH TIME. THE GFS AND
ECMWF ARE FAIRLY SIMILAR IN SLOWLY MOVING THE UPPER TROUGH INTO THE
SOUTHERN PLAINS STATES BY LATE TUESDAY...WITH AN AREA OF SHOWERS AND
STORMS EXPECTED TO SLOWLY MOVE INTO MISSOURI...ARKANSAS AND THROUGH
EASTERN OKLAHOMA AND NORTH TEXAS. THE UPPER LOW IS THEN EXPECTED TO
SLOWLY SHIFT NORTHEAST INTO NORTHEAST OKLAHOMA/SOUTHWEST MISSOURI BY
12Z THURSDAY...WITH INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS
ESPECIALLY BY WEDNESDAY AFTERNOON THROUGH THURSDAY AND THURSDAY
NIGHT FOR THE FORECAST AREA. WILL ALSO LOWER TEMPS MORE IN LINE WITH
THE GFS NUMBERS AS THE INCREASE IN CLOUDS AND PRECIP CHANCES SHOULD
FURTHER LIMIT HEATING ON THURSDAY AND INTO FRIDAY. WILL ALSO CONTINUE
TO WATCH FOR TIMING OF THE UPPER SYSTEM AND CONSISTENCY RELATED TO
EXPECTED HEAVY RAINFALL AND STRONG TO SEVERE STORM POTENTIAL DUE TO
THE PROBABLE SLOW MOVEMENT OF THE BOUNDARY THROUGH THE FORECAST AREA.

AS THE FRONTAL BOUNDARY ALONG AND AHEAD OF THE UPPER LOW MOVES
THROUGH THE AREA BY LATE THURSDAY...MUCH OF THE UPPER ENERGY WITH THE
SYSTEM WILL ALSO SHIFT NORTH OF THE FORECAST AREA BY FRIDAY. WILL
CONTINUE WITH JUST A CHANCE OF SHOWERS AND STORMS FOR FORECAST AREA
ON FRIDAY DUE TO THE PROXIMITY OF THE UPPER SYSTEM ACROSS WESTERN
KENTUCKY AT THAT TIME. THE ECMWF DIFFERS FROM THE GFS RELATED TO THE
MOVEMENT OF THE FRONTAL BOUNDARY...AS THE ECMWF IS QUICKER WITH THE
BOUNDARY MOVEMENT THROUGH THE FORECAST AREA...COMPARED TO THE GFS.
BY FRIDAY...THE GFS CONTINUES TO INDICATE THAT THERE WILL BE SOMEWHAT
OF A DRY SLOT MOVING THROUGH THE FORECAST AREA...WHILE THE ECMWF IS
LESS CERTAIN OF THIS SOLUTION. FOR NOW...WILL FOLLOW CLOSER TO THE
UNCERTAIN ECMWF SOLUTION UNTIL MORE MODEL CONSISTENCY IS ACHIEVED.

TT

&&

.HUN WATCHES/WARNINGS/ADVISORIES...

AL...NONE.

TN...NONE.

&&

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

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1034 PM CDT SAT MAR 17 2012

ALZ001>010-016-TNZ076-096-097-181015-
LAUDERDALE-COLBERT-FRANKLIN AL-LAWRENCE-LIMESTONE-MADISON-MORGAN-
MARSHALL-JACKSON-DEKALB-CULLMAN-MOORE-LINCOLN-FRANKLIN TN-
1034 PM CDT SAT MAR 17 2012

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

.DAY ONE...REMAINDER OF TONIGHT...

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

ISOLATED THUNDERSTORMS WILL BE POSSIBLE OVERNIGHT...PRIMARILY ACROSS
THE SOUTHERN MIDDLE TENNESSEE COUNTIES. OCCASIONAL CLOUD TO GROUND
LIGHTNING AND LOCALLY HEAVY RAINFALL CAN BE EXPECTED WITH THE
STRONGEST STORMS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY...

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

A LARGE...SLOW MOVING AREA OF LOW PRESSURE WILL MOVE ACROSS THE
TENNESSEE VALLEY WEDNESDAY THROUGH FRIDAY. GUSTY WINDS AND LOCALLY
HEAVY RAINFALL WILL BE POSSIBLE WITHIN SHOWERS AND THUNDERSTORMS...
MAINLY ON WEDNESDAY AND THURSDAY.

.SPOTTER CALL TO ACTION STATEMENT...

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

70/DD