000
FXUS64 KOHX 150910
AFDOHX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
410 AM CDT SAT JUN 15 2013

.DISCUSSION...

CURRENT RUC ANALYSIS SHOWS A SURFACE RIDGE AXIS FIRMLY ENSCONCED
OVER THE OHIO AND TENNESSEE VALLEYS THIS MORNING...AND A DECENTLY
AMPLIFIED RIDGE JUST TO OUR WEST. THE POSITION OF THIS UPPER RIDGE
HAS MIDDLE TENNESSEE IN A NORTHWESTERLY FLOW ALOFT...AND AS THOSE
OF YOU WHO FOLLOW THESE WRITINGS KNOW ALL TOO WELL...NW FLOW ALOFT
CAN BE VERY TRICKY. THIS MORNING IS NO DIFFERENT. AN MCS OVER NE
MISSOURI AND WEST CENTRAL ILLINOIS IS ON A TRAJECTORY TOWARDS
TENNESSEE. LATEST SHORT TERM GUIDANCE SHOWS THIS SYSTEM DYING AS
IT MOVES SOUTHEASTWARD ALONG THE MISSISSIPPI RIVER...AND DUE TO
THE SUBSIDENCE IN PLACE I WOULD HAVE TO AGREE WITH THOSE
SOLUTIONS...BUT IT WILL HAVE TO BE MONITORED THROUGH THE MORNING
HOURS. IN THE LEAST...BLOW OFF FROM THIS MCS WILL LIKELY USHER IN
HIGH CLOUDS OVER THE STATE...WHICH COULD HAMPER OUR ABILITY TO
REACH THE MIDDLE TO UPPER 80S TODAY. WILL HOLD FIRM THOUGH AS WE
SHOULD HAVE ENOUGH SUBSIDENCE TO GET US CLOSE TO THOSE NUMBERS.

AS WE MOVE INTO TONIGHT AND TOMORROW...THE SURFACE RIDGE WILL MOVE
EASTWARD AND PUT MIDDLE TENNESSEE INTO SOUTHERLY SURFACE FLOW.  THIS
WILL INCREASE MOISTURE ACROSS THE STATE DRAMATICALLY BY SUNDAY
AFTERNOON.  DEW POINTS WILL CREEP TOWARDS THE 70 DEGREE MARK MUCH
LIKE THE EARLY PART OF LAST WEEK.  THIS INCREASE IN BOUNDARY LAYER
MOISTURE...COUPLED WITH THE DEGRADATION OF THE UPPER RIDGE WILL OPEN
US UP TO THE POTENTIAL FOR THUNDERSTORM DEVELOPMENT STARTING SUNDAY
AFTERNOON.  WHILE COVERAGE OF ANY CONVECTION SHOULD BE SCATTERED AT
BEST...MID-LEVEL LAPSE RATES SUNDAY AFTERNOON ON THE ORDER OF 6.5 TO
7 DEGREES CELSIUS WILL CREATE A VERY UNSTABLE ENVIRONMENT AND ANY
SHORTWAVE THAT MOVES THROUGH THE TENNESSEE VALLEY WILL LIKELY SPARK
AT LEAST A FEW THUNDERSTORMS...SOME OF WHICH COULD BE STRONG TO
SEVERE.  IF THERE IS ANY GOOD NEWS IN THIS...A LACK OF DEEP LAYER
SHEAR SHOULD PREVENT ANY REAL ORGANIZATION SUNDAY.  BECAUSE OF THIS
I WILL GO AHEAD AND HIGHLIGHT THIS ISOLATED THREAT OF SEVERE IN THE
HAZARDOUS WEATHER OUTLOOK FOR DAMAGING STRAIGHT LINE WINDS...LARGE
HAIL...AND HEAVY DOWNPOURS WHICH COULD LEAD TO SOME LOCALIZED
FLOODING...BUT THE THREAT SHOULD END AS THE SUN GOES DOWN SUNDAY
EVENING.

BY SUNDAY NIGHT WE SHOULD BEGIN TO SEE A WEAK AND DIFFUSE FRONTAL
SYSTEM DROPPING INTO THE REGION FROM THE NORTH.  THIS FRONT WILL
LIKELY SPELL A WET BEGINNING TO THE WORKWEEK AS IT MOVES INTO THE
TENNESSEE VALLEY.  WITHOUT ANY KICKER EXPECTED TO PUSH IT THROUGH
THE STATE...THE FRONT COULD BECOME QUASI-STATIONARY AND OPEN US UP
TO A GOOD AMOUNT OF RAINFALL THROUGH TUESDAY AFTERNOON AS MULTIPLE
SHORTWAVES TRAVERSE THIS FRONT.  IT IS YET TO BE DETERMINED HOW
PROGRESSIVE THIS FRONT WILL BE.  THE LATEST EURO GUIDANCE WANTS TO
HANG THE FRONT UP OVER SOUTHERN PORTIONS OF TENNESSEE/NORTHERN
PORTIONS OF ALABAMA...AND THE GFS IS MUCH MORE PROGRESSIVE...PUSHING
THE FRONT COMPLETELY OUT OF THE STATE EARLY TUESDAY.  WITH THE
NUMBER OF DIVERSE SOLUTIONS OF THE GFS ENSEMBLE AND THE PROPENSITY
OF THE GFS TO BE TOO PROGRESSIVE...I WILL GO WITH THE SLOWER EURO
SOLUTION AND KEEP POPS IN THROUGH TUESDAY NIGHT.  AS FAR AS THE
INTENSITY OF THUNDERSTORMS GOES MONDAY AND TUESDAY...WILL REFRAIN
FROM ADDING ANY SEVERE WORDING FOR THESE PERIODS...BUT IT MAY BECOME
NECESSARY IN FUTURE FORECASTS PACKAGES.

BY WEDNESDAY OR WEDNESDAY NIGHT MIDDLE TENNESSEE SHOULD BEGIN TO DRY
OUT...BUT TEMPERATURES WILL NOT GET MUCH OF A CHANCE TO SUBSIDE.  WE
MAY SEE AFTERNOON TEMPS BACK TOWARDS NORMAL TUESDAY AND WEDNESDAY...
BUT DEW POINTS WILL REMAIN ELEVATED AND WITH RIDGING EXPECTED TO
BUILD BACK INTO THE SOUTH...TEMPERATURES SHOULD WARM BACK ABOVE
NORMAL BY THE END OF THE WEEK AND INTO NEXT WEEKEND.

27/UNGER

&&

.AVIATION...06Z TAF DISCUSSION.

VFR. IR SATELLITE IMAGERY CONTINUES TO SHOWS SOME CIRRUS
SPREADING ACROSS THE MID STATE FROM THE NORTHWEST...AND SCT-BKN
CIRRUS WILL REMAIN THROUGHOUT THE TAF PERIOD. DRY LOW LEVELS
SHOULD LIMIT FOG FORMATION OVERNIGHT BUT CANNOT RULE OUT BRIEF
MVFR VIS AT CKV/CSV IN THE 10-12Z TIMEFRAME. LIGHT TO CALM WINDS
OVERNIGHT WILL BECOME SOUTH TO SOUTHWEST 5-10 KTS SATURDAY
MORNING.

SHAMBURGER

&&

.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE      89  67  91  69 /   0  05  30  40
CLARKSVILLE    89  65  91  68 /   0  05  30  30
CROSSVILLE     84  63  84  66 /   0  05  30  40
COLUMBIA       90  67  91  70 /   0  05  30  30
LAWRENCEBURG   90  66  91  69 /   0  05  30  30
WAVERLY        89  65  91  69 /   0  05  30  30

&&

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

&&

$$

27