Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 300450
AFDOHX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
1150 PM CDT FRI AUG 29 2014

.UPDATE...FOR 06Z AVIATION.

&&

.AVIATION...06Z TAF DISCUSSION.

FLIGHT CATEGORIES WILL BEGIN TO DETERIORATE BY EARLY AFTERNOON
SATURDAY AS LOW LEVEL MOISTURE INCREASES AHEAD OF APPROACHING
SHOWERS AND THUNDERSTORMS. IFR TO MVFR CONDITIONS WILL BE LIKELY
BY 21Z FOR KCKV AND KBNA...WITH AT LEAST MVFR SPREADING OVER THE
PLATEAU AND KCSV BY 00-01Z SUNDAY. SOME OF THESE RAINS MAY BE
HEAVY AT TIMES...SO VIS MAY BE REDUCED A BIT MORE THAN
INDICATED...BUT MOST SHOULD HOVER IN THE MVFR RANGE. WINDS WILL
BE GENERALLY OUT OF THE SOUTH IN THE 8-10KT RANGE BUT HIGHER GUSTS
ARE LIKELY WITH SOME OF THE TSRA.

UNGER

&&

.PREV DISCUSSION... /ISSUED 842 PM CDT FRI AUG 29 2014/

UPDATE...
SOME FINE TUNING OF THE POP/WX SEEMED WARRANTED TONIGHT AS THE
LONG ADVERTISED RAIN PATTERN CONTINUES TO BE INDICATED IN BOTH
MODELS. SOME SUBTLE DIFFERENCE IN THE ECMWF/GFS...MAINLY IN THE INTENSITY OF
A 850 MB LLJ...WILL CONTINUE TO MAKE PINPOINTING AREAS OF HIGHEST
RAINFALL POTENTIAL SOMEWHAT COMPLICATED. WHILE CONFIDENT THAT JUST
ABOUT EVERYWHERE IN THE MID-STATE WILL BE SEEING RAINFALL BETWEEN
18Z SAT AND 12Z SUNDAY...18Z MODEL RUNS CONTINUE TO SHOW A WETTER
PATTERN FOR THE TN RIVER VALLEY AND DRIER DEPICTION FOR THE
CUMBERLAND PLATEAU. THIS IS LARGELY DUE TO THE MAIN DYNAMICAL
SUPPORT...500 MB JET AND 850 MB SHORTWAVE DISTURBANCE...BEING
CONFINED TO WEST TN AND BRUSHING OUR NW COUNTIES. THIS WOULD BE
BETWEEN 00Z AND 03Z IF THE 18Z MODEL RUNS ARE CORRECT.

CONVECTIVE PARAMETERS ARE NOT ENOUGH TO WARRANT MUCH ON THE SIDE
OF SEVERE POTENTIAL...ESPECIALLY WITHOUT MUCH SURFACE FORCING TO
LIFT PARCELS...BUT WITH PWATS WELL OVER 2 INCHES..THE DYNAMICS
ALONE SHOULD BE ENOUGH TO WARRANT LIGHTNING ACTIVITY. THE ADDED
CONVECTIVE ELEMENT OF ~1000 J/KG AND LI`S AROUND -5 COULD RESULT IN
SOME HEAVY DOWNPOURS AND GUSTY WINDS UP TO 40 MPH.

TWEAKED THE UPDATED WPC QPF FORECAST TO MIRROR OUR POP CHANCES IN
THE GRIDS. THIS LEAVES A 48 HOUR TOTAL JUST ABOUT IN LINE WITH THE
WPC 48 HOUR TOTAL WITH MINOR DISCREPANCIES IN THE TIMING OF THE
HEAVIEST RAINS.

&&

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

&&

$$

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