National Weather Service Weather Forecast Office

Area Forecast Discussion

367
FXUS64 KOHX 201442
AFDOHX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
942 AM CDT MON MAY 20 2013

.UPDATE...
DEWPOINTS ON THE INCREASE OVER THE LAST FEW HOURS. SHOULD SEE THE
TREND WHEREBY AN INCREASE IN CAPES AND DEWPOINTS CONTINUE INTO THE
AFTERNOON. NO REAL DYNAMICS TO SPEAK OF THOUGH AS THE BEST
ORGANIZED CONVECTION REMAINS OUT WEST ALONG THE CENTRAL PLAINS.
THAT ASSOCIATED FRONTAL BOUNDARY WILL REMAIN TO OUR WEST THROUGH
AT LEAST TODAY AND TONIGHT.

FOR THE UPDATE...WILL INCREASE SKY COVER IN GRIDS AS WELL AS LOWER
TEMPS A DEGREE OR TWO. LATEST MAV GUIDANCE HAS BACKED OFF A FEW
DEGREES AS MORE IN THE WAY OF CLOUD COVER IS EXPECTED.

OTW...NO OTHER CHANGES...ISOLATED AFT SHOWERS AND TSTMS ARE IN THE
GRIDS AND THAT LOOKS SUFFICIENT.

&&

.PREV DISCUSSION... /ISSUED 626 AM CDT MON MAY 20 2013/

UPDATE...

12Z TAF DISCUSSION.

AVIATION...

IR SATELLITE IMAGERY SHOWS LOW CLOUDS HAVE VERY RAPIDLY ADVECTED
NORTHWARD INTO THE CENTRAL MID STATE PAST HOUR WITH MVFR CIGS NOW
AT BNA. COULD ALSO SEE MVFR CIGS AT CKV BRIEFLY THIS MORNING...BUT
BOTH BNA/CKV EXPECTED TO BECOME VFR BY LATE MORNING. PATCHY FOG
HAS RESULTED IN OCCASIONAL VIS RESTRICTIONS OVERNIGHT...BUT
EXPECTED TO IMPROVE TO VFR VIS AREAWIDE BY 14Z. OTHERWISE...EXPECT
SCATTERED CU THIS AFTERNOON WITH SOUTH TO SOUTHWEST WINDS 5 TO 11
KTS. AN ISOLATED -SHRA/-TSRA IS POSSIBLE THIS AFTERNOON
ESPECIALLY NEAR CSV...BUT POTENTIAL APPEARS TOO REMOTE TO MENTION
IN TAF ATTM.

PREV DISCUSSION... /ISSUED 205 AM CDT MON MAY 20 2013/

DISCUSSION...HIGH PRESSURE REMAINS SITUATED OFF TO THE EAST, WITH
SURFACE PRESSURE GRADIENT STARTING TO INCREASE ACROSS MIDDLE
TENNESSEE. MOSTLY CLEAR SKIES HAVE SETTLED IN ACROSS THE MID
STATE, WITH FOG EXPECTED TO DEVELOP TOWARD MORNING, ESPECIALLY IN
AREAS THAT RECEIVED RAINFALL ON SUNDAY. HAD ORIGINALLY GONE WITH A
DRY FORECAST TODAY, BUT THE NAM SOUNDING FOR BNA THIS AFTERNOON
SHOWS DEEP LEFTOVER INSTABILITY, WITH A CAPE EXCEEDING 3000 J/KG
DURING PEAK HEATING AND A LIFTED INDEX OF -7. THESE FIGURES APPEAR
TO BE REPRESENTATIVE ACROSS THE ENTIRE MID STATE. THE SOUNDING IS
A BIT DRY, WITH ONLY A SHALLOW MOIST LAYER IN THE LOW LEVELS, BUT
GIVEN THAT SEVERAL PLACES WILL HIT 90 DEGREES TODAY, CANNOT RULE
OUT ISOLATED CELLS POPPING UP DURING THE AFTERNOON. THE SPC`S
LATEST DAY 2 OUTLOOK PLACES ABOUT THE WESTERN 1/3 OF MIDDLE
TENNESSEE UNDER A SLIGHT RISK OF SEVERE STORMS TUESDAY AND TUESDAY
NIGHT. ACTIVITY WILL FURTHER INCREASE ON WEDNESDAY AS THE ACTUAL
COLD FRONT ARRIVES.

&&

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

$$

21