Special Weather Statement, NWS Nashville, TN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
1209 PM CDT WED JUL 10 2013

.UPDATE...ADDED AVIATION SECTION FOR 18Z TAF'S.

&&

.AVIATION...BNA/CKV/CSV...THINGS ARE QUIET AT THE MOMENT ACROSS
MIDDLE TENNESSEE, BUT THE ATMOSPHERE REMAINS VERY MOIST AND
HIGHLY UNSTABLE, AND STORMS ARE EXPECTED DURING THE AFTERNOON.
HRRR EVEN SUGGESTS POSSIBLE ORGANIZED CONVECTION MOVING FROM WEST
TO EAST AFTER 18Z. ACTIVITY MAY LAST INTO THE EVENING ACROSS THE
CUMBERLAND PLATEAU, WITH FOG POSSIBLE AT CKV AND CSV OVERNIGHT.

&&

.PREV DISCUSSION... /ISSUED 1119 AM CDT WED JUL 10 2013/

UPDATE...
AIRMASS CONTINUES TO HEAT/DESTABILIZE LATE THIS MORNING...WITH DEWS
HOLDING IN THE LOW/MID 70S. LATEST AVAILABLE MODELS SHOWING INSTABILITY
HIGH END THIS AFTERNOON/EVENING...WITH SHEAR STAYING VERY MINIMAL.
EFFECTIVE BULK SHEAR PROGGED TO STAY BELOW 20KT THROUGH THE LATE
AFTERNOON. MODELS RAMPING UP CONVECTION AFT 17Z...WHICH WOULD BE
EXPECTED GIVEN PARAMETERS. PRECIP WATER HANGING AROUND 2.0 SO DO
EXPECT HEAVY DOWNPOURS...BUT STORMS SHOULD HAVE ENOUGH MOVEMENT TO
LIMIT THREAT OF FLASH FLOODING. LARGE HAIL CHANCE ALSO SEEMINGLY
SLIM WITH WETBULB ZERO/FREEZING LVL ROUGHLY 15KFT+ INTO LATE EVENING.

RAISED POPS SOME NORTH/EAST FOR THE AFTERNOON. MAY MAKE VERY SMALL
TEMP TWEAKS AS WELL. OTHERWISE NO CHANGES.

PREV DISCUSSION... /ISSUED 618 AM CDT WED JUL 10 2013/

UPDATE...FOR AVIATION.

AVIATION...
12Z TAFS...A FEW SHOWERS ARE DEVELOPING OVER THE PLATEAU REGION
THIS MORNING...SO INCLUDING VCSH FOR CSV. OTHERWISE...LOOK FOR
GENERALLY INCREASING COVERAGE OF SHRA/TSRA FROM LATE MORNING
THROUGH THIS EVENING AS A COLD FRONT PUSHES INTO THE WARM...HUMID
AND UNSTABLE AIR OVER MID TN. A FEW STRONG TSRA ARE EXPECTED WITH
HEAVY DOWNPOURS AND LOCALLY GUSTY WINDS. AT LEAST SCT SHRA/TSRA
WILL CONTINUE THROUGH TONIGHT AS THE FRONT MOVES SLOWLY ACROSS THE
AREA.

13

PREV DISCUSSION... /ISSUED 328 AM CDT WED JUL 10 2013/

DISCUSSION...
FORECAST REASONING WILL LEAN TOWARD A CONSENSUS MODEL SOLUTION
COMPROMISE FOR THE FORECAST PERIOD UNLESS OTHERWISE NOTED.

FORECAST QUANDARIES...STRONG TO SVR TSTM POTENTIAL ALONG WITH
POTENTIAL FOR HEAVY RAINFALL THIS AFTERNOON INTO THU...OVERALL
WX PATTERN LATE WEEK INTO FIRST PART OF NEXT WEEK...TEMPS.

STILL EXPECTING NWLY UPPER LEVEL FLOW PATTERN THAT IS BEING ESTABLISHED
ACROSS THE MID STATE TO SEND SOME UPPER LEVEL DISTURBANCES DROPPING SE
FROM THE MID MS AND OHIO RIVER VALLEYS TODAY. THIS WILL OCCUR AHEAD OF
AN UNUSUAL ACTUAL PROGGED SUMMERTIME COLD FRONTAL PASSAGE...WHICH
SHOULD BE APPROACHING WRN KY BY THE EVENING HRS...THEN CONTINUE MOVING
SEWD AND MOVE INTO NW PORTIONS OF THE MID STATE BY EARLY THU MORNING.
STILL ALSO EXPECT OVERALL INCREASED MOISTURE POOLING AHEAD OF THIS
FRONTAL PASSAGE...WITH MODEL CONSENSUS STILL SHOWING PW'S AROUND TWO
INCHES AS THE AFTERNOON HRS APPROACH AND INTO AT LEAST THE EVENING HRS
TONIGHT...RESULTING IN THE POTENTIAL FOR NUMEROUS SHWRS AND TSTMS W TO
SCT SHWRS/TSTMS E BY THIS AFTERNOON...WITH NUMEROUS SHWRS/TSTMS ALL
LOCATIONS TONIGHT...SUPPORTING THE POTENTIAL OF BRIEF HEAVY RAINFALL.
ALONG WITH THIS...DIURNAL INFLUENCES SHOULD KICK ENOUGH ALSO TO SUPPORT
SOME STRONG TO POSSIBLY EVEN SVR TSTMS ACROSS LOCATIONS GENERALLY
ALONG AND N OF I-40 AND ALONG AND W OF I-65. WILL MENTION THIS POSSIBILITY
ALSO IN THIS MORNING'S HWO ISSUANCE. WITH POTENTIAL FOR MORE SHWRS/TSTMS
NW...WILL UNDERCUT GFS MOS VALUES HERE BY A COUPLE OF DEGREES FOR HIGHS
TODAY...OTHERWISE GO WITH MAINLY LOW 90S ACROSS THE MID STATE...WITH MID
TO UPPER 80S PLATEAU. AS FOR TONIGHT...WITH ADDITIONAL CLOUD COVERAGE AND
EXPECTED RAINFALL...WILL KEEP LOWS MAINLY IN THE LOWER 70S...UPPER 60S TO
AROUND 70 PLATEAU.

THIS COLD FRONT IS STILL EXPECTED TO PUSH S OF THE MID STATE DURING THE
DAY ON THU...AND THUS WILL TAPER POPS OFF TO A SLIGHT CHANCE ACROSS NW
PORTIONS OF THE MID STATE DURING THE MORNING HRS...WITH LIKELY POPS
CONTINUING ACROSS ERN PORTIONS DURING THE MORNING HRS. WILL KEEP THE
MENTION IN THIS MORNING'S HWO FOR LOCALLY HEAVY RAINFALL ACROSS ERN
PORTIONS OF THE MID STATE TOO FOR THU MORNING. EXPECTING DRIER AIR TO
HAVE WORKED ACROSS MOST OF THE MID STATE DURING THE AFTERNOON HRS...WITH
GENERALLY A SLIGHT CHANCE OF SHWRS/TSTMS REMAINING ACROSS THE SRN 3RD OF
THE MID STATE THU AFTERNOON. AFTERNOON HIGH TEMPS WILL BE SLIGHTLY COOLER
THAN THOSE EXPECTED TODAY...WITH HIGHS MAINLY IN THE MID TO UPPER 80S.
OTHER THAN SOME POSSIBLE EVENING ISO SHWRS/TSTMS PLATEAU ON THU NIGHT...THE
MID STATE WILL BE DRY AS DRIER AIR CONTINUES TO WORK ACROSS THE AREA...WITH
LOWS IN THE LOW 60S. FRI IS EXPECTED TO BE QUITE A PLEASANT SUMMER DAY WITH
MOCLR SKIES AND HIGHS IN THE MID 80S...AROUND 80 PLATEAU...WITH DECREASED
HUMIDITY VALUES FROM THOSE THAT WE HAVE BEEN EXPERIENCING FOR THE PAST FEW
DAYS.

AS FOR FRI NIGHT THRU TUE...SOME QUANDARIES STILL ABOUND HERE IN THIS
PART OF THE FORECAST PERIOD...BUT NOT AS MUCH AS AROUND THIS TIME
YESTERDAY. LATEST DGEX SOLUTION STILL THE ODD MODEL OUT WITH CLOSED LOW
NOW PROGGED TO GO ACROSS THE NRN GULF THE FIRST PART OF THE WEEKEND.
LATEST GFS MORE IN LINE WITH IMPACTS OF CURRENT TS CHANTAL ACROSS THE
SE U.S...WITH NO DIRECT IMPACT TO THE MID STATE ANTICIPATED AT THIS
TIME EXPECT FOR POSSIBLY SOME ADDITIONAL MOISTURE BEING ADVECTED
ACROSS OUR AREA. THE LATEST GFS/EURO MORE IN LINE WITH EACH OTHER OVERALL
IN THE SFC AND UPPER LEVEL PATTERN THAN THIS TIME YESTERDAY AT LEAST
THRU THE WEEKEND. THE GFS AND NOW ALSO THE EURO PICKING UP ON THIS
ODD RETROGRESSION OF A MID-ATLANTIC CLOSED LOW BACK INTO GA BY NEXT
TUE IF YOU BELIEVE THE GFS...AND IF YOU LEAN TOWARD THE EURO...ACTUALLY
MOVING ACROSS THE MID STATE DURING THE DAY ON TUE. WHATEVER ACTUAL PATTERN
TAKES PLACE...ESPECIALLY WITH CHANTAL MOVEMENT AND POTENTIAL LONGEVITY...
IT CONTINUES TO LOOK LIKE THERE WILL BE AT LEAST LOW LEVEL MOISTURE
CONTINUANCE ACROSS THE SE U.S. SUN THRU TUE WITH AT LEAST A SLIGHT CHANCE
OF SHWRS/TSTMS DURING AT LEAST THE DAYLIGHT HRS DURING THIS TIME PERIOD...
AS AN INVERTED UPPER LEVEL TROUGHING PATTERN ACROSS THE NRN GULF STRETCHING
NEWD INTO THE MID STATE EVENTUALLY MOVES WWD WITH MORE OF AN UNORGANIZED
UPPER LEVEL PATTERN DEPENDENT ON ACTUAL POSITIONS OF UPPER LEVEL
STRENGTHENING ALONG WITH SFC RIDGING STRENGTHENING INFLUENCES AND POSSIBLE
ABOVE MENTIONED UPPER LEVEL LOW MOVEMENT NEAR OR ACROSS MID STATE...
AND WHAT INFLUENCE THAT WILL HAVE ON THE MID STATE'S WX. WITH QUANDARIES
STILL ABOUNDING HERE...WILL GENERALLY LEAN CLOSE TO CURRENT FORECAST
REASONING WITH TEMPS TRENDING AT OR SLIGHTLY ABOVE SEASONABLE NORMAL VALUES.

31

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

ROSE

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE NASHVILLE TN
500 AM CDT WED JUL 10 2013

TNZ005>011-022>034-056>066-075-077>080-093>095-111000-
STEWART-MONTGOMERY-ROBERTSON-SUMNER-MACON-CLAY-PICKETT-BENTON-
HOUSTON-HUMPHREYS-DICKSON-CHEATHAM-DAVIDSON-WILSON-TROUSDALE-
SMITH-JACKSON-PUTNAM-OVERTON-FENTRESS-PERRY-HICKMAN-LEWIS-
WILLIAMSON-MAURY-MARSHALL-RUTHERFORD-CANNON-DE KALB-WHITE-
CUMBERLAND-BEDFORD-COFFEE-WARREN-GRUNDY-VAN BUREN-WAYNE-LAWRENCE-
GILES-
500 AM CDT WED JUL 10 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR MIDDLE TENNESSEE.

.DAY ONE...TODAY AND TONIGHT.

SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED
THROUGH TONIGHT...ESPECIALLY ACROSS LOCATIONS ALONG AND NORTH
OF INTERSTATE 40 AND ALONG AND WEST OF INTERSTATE 65. SOME OF
THESE THUNDERSTORMS MAY REACH STRONG TO SEVERE THRESHOLDS WITH
MAIN CONCERNS BEING DAMAGING WINDS AND LARGE HAIL...AS A COLD
FRONT APPROACHES AND BEGINS TO MOVE INTO MIDDLE TENNESSEE. SINCE
GROUND CONDITIONS REMAIN SATURATED FROM PREVIOUS RAINS...PONDING
OF WATER AND THE POTENTIAL OF LOCALIZED FLOODING MAY OCCUR WHERE
THE HEAVIEST RAINFALL TAKES PLACE.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
CONTINUE THROUGH AT LEAST THE MORNING HOURS ON THURSDAY ACROSS
EASTERN AND SOUTHERN PORTIONS OF MIDDLE TENNESSEE...INCLUDING THE
CUMBERLAND PLATEAU REGION. IN THESE LOCATIONS...LOCALLY HEAVY
RAINFALL WILL CONTINUE TO BE POSSIBLE. SINCE GROUND CONDITIONS
ACROSS THESE AREAS REMAIN SATURATED FROM PREVIOUS RAINS...PONDING
OF WATER AND THE POTENTIAL OF LOCALIZED FLOODING MAY OCCUR WHERE
THE HEAVIEST RAINFALL TAKES PLACE.

.SPOTTER CALL TO ACTION STATEMENT...

EVEN THOUGH ANY STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED TO BE
BRIEF AND ISOLATED, SPOTTERS ARE ENCOURAGED TO CLOSELY MONITOR
WEATHER CONDITIONS AND BE PREPARED TO CALL IN ANYTHING REACHING
REPORTING CRITERIA.

SPOTTERS AND LOCAL EMERGENCY MANAGEMENT OFFICIALS ARE ENCOURAGED
TO REPORT HEAVY RAINFALL AMOUNTS TO THE NATIONAL WEATHER SERVICE
IN NASHVILLE ALSO.

SPOTTER THUNDERSTORM REPORTING CRITERIA...
TORNADO
FUNNEL CLOUD
FLOODING
HAIL >= 1/2 INCH
WINDS > 50 MPH (MEASURED)
STRUCTURAL DAMAGE
TREES OR POWER LINES DOWN

31

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NASHVILLE TN
913 AM CDT WED JUL 10 2013

TNZ005-006-101445-
MONTGOMERY-STEWART-
913 AM CDT WED JUL 10 2013

...SIGNIFICANT WEATHER ADVISORY FOR MONTGOMERY AND STEWART
COUNTIES...

AT 908 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A STRONG THUNDERSTORM NEAR BIG ROCK...MOVING EAST AT 15 MPH.

SOME LOCATIONS IN THE PATH INCLUDE BIG ROCK...INDIAN MOUND AND
WOODLAWN.

HALF INCH SIZE HAIL...AND WINDS 30 TO 40 MPH ARE EXPECTED WITH THIS
STORM.

LAT...LON 3665 8746 3642 8743 3641 8779 3659 8782

ROSE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE NASHVILLE TN
155 PM CDT WED JUL 10 2013

TNZ028-030-064-101945-
DE KALB-SMITH-WILSON-
155 PM CDT WED JUL 10 2013

...SIGNIFICANT WEATHER ADVISORY FOR DE KALB...SMITH AND WILSON
COUNTIES...

AT 152 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A STRONG THUNDERSTORM NEAR BELINDA CITY...MOVING EAST AT 15 MPH.

SOME LOCATIONS IN THE PATH INCLUDE GLADEVILLE...LEBANON...CEDARS OF
LEBANON STATE PARK...TUCKERS CROSSROADS...WATERTOWN AND ALEXANDRIA.

HALF INCH SIZE HAIL...AND WINDS 30 TO 40 MPH ARE EXPECTED WITH THIS
STORM.

LAT...LON 3620 8596 3596 8601 3596 8604 3603 8641
      3608 8649 3623 8646

ROSE