Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 180228 AAC
AFDOHX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NASHVILLE TN
928 PM CDT FRI APR 17 2015

.UPDATE...
UPDATED TO REMOVE MENTION OF LIGHT EVENING SHWRS FOR TONIGHT FROM
THE SUITE OF FORECAST PRODUCTS. REMAINDER OF FORECAST REMAINS ON
TRACK.
&&

.PREV DISCUSSION.../ISSUED 645 PM CDT FRI APR 17 2015/

UPDATE...ADDED AVIATION SECTION.

AVIATION...BNA/CKV/CSV...MAINLY VFR CONDITIONS WILL PERSIST INTO
THIS EVENING. LATER TONIGHT...AREAS OF FOG AND LOW CLOUDS WILL
DEVELOP...WITH MAINLY IFR CONDITIONS BY DAYBREAK (12Z)
SATURDAY...AND POSSIBLY SOME LIFR. EXACT VSBYS/CIGS ARE HARD TO
DETERMINE AT THIS TIME...SO EXPECT SEVERAL AMENDMENTS THROUGH THE
NIGHT AS THE AREAS OF FOG AND STRATUS DEVELOP. CONDITIONS ARE
EXPECTED TO IMPROVE TO VFR AGAIN BY 18/16Z. WINDS WILL BE LIGHT
THROUGH THE TAF PERIOD...MAINLY FROM THE ENE.

13

PREV DISCUSSION.../ISSUED 631 PM CDT FRI APR 17 2015/

HAVE UPDATED THE SUITE OF FORECAST PRODUCTS BASED ON CURRENT SFC
OBS...SATELLITE...AND REGIONAL RADAR TRENDS...ALONG WITH CONSENSUS
OF SHORT RANGE MODELS...IN SHOWING SOME LINGERING SHWRS THRU THE MID
EVENING HRS ACROSS LOCATIONS APPROACHING THE TN/AL BORDER AND THE
SRN HALF OF THE CUMBERLAND PLATEAU REGION. BELIEVE THE MID STATE
WILL REMAIN DRY REMINDER OF TONIGHT. WILL EXTEND AREAS FOG THRU MID
MORNING HRS.

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PREV DISCUSSION.../ISSUED 318 PM CDT FRI APR 17 2015/

SHORT TERM...IT WAS MOSTLY CLOUDY AND SEASONABLY MILD ACROSS THE
MID STATE THIS AFTERNOON, WITH 2 PM TEMPERATURES MAINLY IN THE
UPPER 60S TO AROUND 70. AN UPPER LEVEL DISTURBANCE, SCOOTING TO
OUR SOUTH, ACROSS MISSISSIPPI AND ALABAMA, WAS PRODUCING SOME
ISOLATED SHOWERS EXTREME SOUTHERN PARTS OF THE MID-STATE AND
THOSE COULD LINGER INTO THE EVENING HOURS AS WELL. IN FACT,
WOULDN`T BE SURPRISED TO SEE A SHOWER OR THUNDERSTORM POP UP AS
FAR NORTH AS CSV THIS EVENING.

ONCE THE SHORTWAVE MOVES EAST OF OUR AREA LATE THIS EVENING, BELIEVE
AT LEAST PARTIAL CLEARING WILL ENSUE OVER MOST OF OUR FORECAST
AREA AND ALLOW FOR THE DEVELOPMENT OF AREAS OF FOG.  ANY FOG THAT
FORMS WILL HAVE A TENDENCY TO LIFT AND FORM A LOW OVC CIG.
HOWEVER, IT`S POSSIBLE THAT SOME OF THE FOG COULD BECOME LOCALLY
DENSE, ESPECIALLY OVER ABOUT THE WESTERN TWO-THIRDS OF MIDDLE
TENNESSEE.

MODELS CONTINUE TO SLOW DOWN THE RETURN MOISTURE ON SATURDAY, AND
IT LOOKS LIKE THE BEST CHANCE FOR AFTERNOON SHOWERS AND
THUNDERSTORMS WILL BE CONFINED TO OUR SOUTHWESTERN COUNTIES. THAT
MEANS, MUCH OF THE MID-STATE COULD EEK OUT ANOTHER MOSTLY DRY DAY.

STILL LOOKS LIKE SHOWERS AND THUNDERSTORMS WILL OVERSPREAD THE
REGION SATURDAY NIGHT, AS A SURFACE LOW MOVES NORTHWARD ACROSS
WESTERN TN INTO WESTERN KY. ONE OF THE MAIN CONCERNS WITH THESE
SHOWERS AND STORMS WILL BE LOCALLY HEAVY DOWNPOURS, WITH PWS
FORECAST TO BE AROUND 1.5" THE RAINS WE HAD EARLIER THIS WEEK
HAVE SATURATED THE GROUND PRETTY WELL. SO, ANY HEAVY DOWNPOURS
THAT OCCUR SATURDAY NIGHT AND SUNDAY MORNING WILL LIKELY PRODUCE
PONDING OF WATER IN LOW LYING AREAS AND COULD LEAD TO ISOLATED
FLASH FLOODING.

WE WILL HAVE A LOW CAPE/HIGH HELICITY ENVIRONMENT DURING THE
SAT/SUN EVENT, AND WITH THE SURFACE LOW TRACKING JUST TO OUR WEST,
WE`LL HAVE TO KEEP AN EYE OUT TO SEE IF ANY OF THE CONVECTION IS
ABLE TO TAP THAT MINIMAL CAPE AND PRODUCE ANY STRONG-TO-SEVERE
THUNDERSTORMS. SWATH OF LOW LEVEL HELICITIES AROUND 300 M2/S2
SPREADS ACROSS THE AREA BTWN 09Z AND 13Z EARLY SUNDAY MORNING, BUT
AS OF NOW, SPC HAS THE MID-STATE ONLY IN A GENERAL TSTM AREA
THROUGH 12Z SUN. MOST RECENT MODEL RUNS SUGGEST THE BEST CHANCE
FOR ISOLATED STRONG-TO-SEVERE STORMS WOULD PROBABLY BE OVER OUR
EASTERN COUNTIES DURING A RELATIVELY BRIEF WINDOW BETWEEN 11Z AND
15Z, WHEN THE RISING SUN SHOULD BE ABLE TO KICK UP THE CAPES JUST
A BIT. IF HELICITIES REACH FORECAST VALUES, IT WOULDN`T BE OUT OF
THE QUESTION TO SEE A FEW BRIEF TORNADOES TRY TO SPIN UP. HOWEVER,
ON THE OTHER HAND, WITH SKIES EXPECTED TO REMAIN MOSTLY CLOUDY,
SFC-BASED CAPES MAY BE DIFFICULT TO GENERATE AND TAP.

A COLD FRONT PUSHES ACROSS THE AREA SUNDAY NIGHT, AND WILL LIKELY
BE ATTENDED BY A SQUALL LINE AND THE POTENTIAL FOR ISOLATED
STRONG-TO-SEVERE THUNDERSTORMS. SPC HAS US IN A SLIGHT RISK FOR
SEVERE STORMS BTWN 12Z/19 AND 12Z/20 AND RIGHT NOW IT LOOKS LIKE
THE MAIN CONCERN WITH THOSE STORMS WILL BE HEAVY DOWNPOURS, GUSTY
STRAIGHT LINE WINDS, AND HAIL.

WE FINALLY GET TO SEE AT LEAST A BRIEF STRETCH OF DRY WEATHER NEXT
TUESDAY AND WEDNESDAY, AS HIGH PRESSURE BUILDS IN OVER THE AREA
AND GIVES US A FEW CHILLY MORNINGS, WITH LOWS IN THE 40S.
MEANWHILE, DAYTIME HIGHS WILL BE SEASONABLY MILD, AND AVERAGE BETWEEN
65 AND 70 DEGREES EACH DAY.

LONG TERM...WE MAY SEE A WARM FRONT LIFT ACROSS OUR AREA AS EARLY
AS WEDNESDAY NIGHT, BRINGING ANOTHER CHANCE FOR SHOWERS AND
THUNDERSTORMS, AND THERE WILL BE AT LEAST A SMALL CHANCE FOR
SHOWERS IN THE FORECAST INTO FRIDAY AS WELL.

19

&&

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

&&
$$
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