Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 041826 AAD
AFDOHX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE NASHVILLE TN
1226 PM CST WED MAR 4 2015

.UPDATE...FOR 18Z AVIATION DISCUSSION.
&&

.AVIATION...18Z AVIATION DISCUSSION.
SEVERAL AMDS POSSIBLE THRU 05/18Z. SIGNIFICANT ICING POTENTIAL ALONG WITH AT
MAINLY IFR CEILINGS/VSBYS THRU 05/18Z. TIMING OF IMPACTS NOT SPECIFICALLY
CERTAIN AND THIS SHOULD BE TAKEN INTO ACCOUNT WITH FM GROUP TIMINGS. COPIOUS
MOISTURE ACROSS MID STATE PRESENTLY PRODUCING LIGHT RAIN WILL TRANSITION TO
A WINTRY MIX...INCLUDING FREEZING RAIN...THEN SNOW/SLEET MIX...AND THEN ALL
SNOW. SFC OBS/CONSENSUS SHORT TERM MODEL TRENDS SHOWING A WINTRY MIX...WITH
FREEZING RAIN POTENTIAL BEGINNING AFTER 04/22Z CKV...05/00Z BNA...AND 05/02Z
CSV. EXPECT A TRANSITION TO A SNOW/SLEET MIXTURE 05/02Z CKV...05/04Z BNA...
AND 05/06Z CSV. EXPECT A TRANSITION TO ALL SNOW 05/13Z CKV...05/12Z BNA...AND
05/17Z CSV.
&&

.PREV DISCUSSION.../ISSUED 1124 AM CST WED MAR 4 2015/

DISCUSSION...
HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO REMOVE NORTHERN PORTIONS
OF MID STATE FROM FLASH FLOOD WATCH. ALSO TWEAKED HRLY TEMP...DEWPOINT...
WIND SPEED/DIRECTION GRIDS. REMAINDER FOR FORECAST THRU AFTERNOON HRS
REMAINS ON TRACK.

PREV DISCUSSION.../ISSUED 1052 AM CST WED MAR 4 2015/

UPDATE...
HAVE UPDATED THE SUITE OF FORECAST PRODUCTS THRU REMAINDER OF THE MORNING HRS
THRU THE AFTERNOON HOURS. FROM 18Z-20Z...ACROSS FAR NW PORTIONS OF MID STATE...
CLARKSVILLE...NWD TO LAND BETWEEN THE LAKES REGION...BELIEVE THAT RAIN AND
FREEZING RAIN WILL START TO MIX IN...AND WILL MOVE THIS AREA SLOWLY EWD WITH
THE CHANCE OF A FREEZING RAIN/SLEET MIXTURE APPROACHING LOCATIONS GENERALLY
AROUND AND NORTH OF I-40 AND GENERALLY AROUND AND WEST OF I-65 BETWEEN 22Z-00Z.
HOWEVER...AM LEAVING ICE AND SLEET/SNOW ACCUMULATIONS CLOSE TO PREVIOUS AMOUNTS
FORECASTED THRU THIS AFTERNOON AS OF THIS TIME. WENT AHEAD ALSO AND TWEAKED HRLY
TEMP...DEWPOINT...WIND SPEED/DIRECTION GRIDS.

PREV DISCUSSION.../ISSUED 546 AM CST WED MAR 4 2015/

UPDATE...ADDED AVIATION SECTION FOR 12Z TAF`S.

AVIATION...BNA/CKV/CSV...COLD FRONT HAS ALREADY PASSED NASHVILLE
WITH RAIN GRADUALLY SPREADING INTO MIDDLE TENNESSEE FROM THE NW.
NEARLY ALL PRECIPITATION IS POST-FRONTAL, SO WITH FALLING
TEMPERATURES EXPECTED THROUGHOUT THE DAY AND TONIGHT, RAIN WILL
SWITCH OVER TO A WINTRY MIX BY 21Z AT CKV, AROUND 00Z AT BNA, AND
03Z AT CSV, WITH IFR CIGS AND REDUCED VSBY THROUGHOUT MOST OF THE
TAF PERIOD.

PREV DISCUSSION.../ISSUED 402 AM CST WED MAR 4 2015/

SHORT TERM...COLD AIR WAS ALREADY STARTING TO REPLACE OUR MILD
TEMPERATURES OVER NORTHWESTERN COUNTIES EARLY THIS MORNING, AND
READINGS WILL START TO TUMBLE OVER OTHER PARTS OF THE MID STATE
AS THE DAY PROGRESSES. AT 3 AM CST, A STRONG COLD FRONT REACHED
FROM JUST EAST OF BWG TO JUST EAST OF MEMPHIS, AND SHOULD BE IN
THE NASHVILLE METRO AREA BY 6 AM CST.

PREVIOUS PRECIP AND QPF GRIDS FROM THE LAST SHIFT LOOK EXCELLENT
AND ARE STILL IN LINE WITH LATEST GUIDANCE. ONLY MADE MINOR
TWEAKS, MAINLY DURING LATE WEDNESDAY NIGHT WHEN IT LOOKS LIKE
PRECIP WILL STILL BE MAINLY A ZR/IP MIX FOR AREAS SOUTH OF CSV-TO-
LAWRENCEBURG LINE. INDEED, WE`LL HAVE TO KEEP A WATCH OVER THOSE
AREAS IN PARTICULAR TO SEE HOW MUCH OF THE PRECIP WILL FALL AS
FREEZING RAIN AND BE PREPARED TO UPGRADE OUR ICE ACCUM GRIDS IF
NECESSARY. RIGHT NOW, IT LOOKS LIKE A LOT OF THE PRECIP WILL FALL
AS SLEET RATHER THAN ZR BUT, OF COURSE, THAT COULD CHANGE. FURTHER
NORTH AND WEST IT STILL LOOKS LIKE WE`LL BE DEALING MAINLY WITH A
SLEET AND SNOW MIX EVEN THOUGH IT WOULDN`T BE SURPRISING FOR THE
PRECIP TO START AS A BRIEF PERIOD OF FREEZING RAIN.

DON`T EXPECT FREEZING TEMPS TO ARRIVE IN OUR NW UNTIL SHORTLY
AFTER NOON--PROBABLY AROUND 2 PM OR 3 PM IN THE CKV AREA. BY
NIGHTFALL EXPECT TRAVEL CONDITIONS TO BE GETTING PRETTY SLOPPY
OVER THE NORTHWEST AND HIGHLAND RIM AREA, NORTH OF NASHVILLE.
RIGHT NOW, IT APPEARS THAT THE TEMP PROBABLY WON`T REACH FREEZING
AT BNA UNTIL SOMETIME BETWEEN 6 PM AND 9 PM. SO, EVEN THOUGH
NASHVILLE PROPER MAY NOT HAVE BAD ROAD CONDITIONS DURING THE LATE
AFTERNOON AND EARLY EVENING, TRAVELERS SHOULD REALIZE THAT CONDITIONS
WILL LIKELY BE CONSIDERABLY WORSE NORTH AND WEST OF THE CITY.

TONIGHT, TRAVEL CONDITIONS WILL BECOME HAZARDOUS AREA-WIDE AS COLD
AIR CONTINUES TO SPREAD SOUTHWARD AND EASTWARD. BY MIDNIGHT,
EXPECT TEMPS TO BE BELOW FREEZING OVER THE NORTHWEST HALF OF
MIDDLE TENNESSEE AND BY 6 AM CST OVER THE ENTIRE MID-STATE. STILL
LOOK FOR HIGHEST SNOW AMOUNTS IN THE NORTHWEST, WITH 3 TO 5 INCHES
OF SNOW AND SLEET EXPECTED TO BE COMMON ALONG THE HIGHLAND RIM AND
NORTHWEST, RANGING TO AROUND 3 INCHES ALONG THE I-40 CORRIDOR AND
NORTHEAST, WITH 2 TO 3 INCHES SOUTHWEST, AND CLOSER TO 1 TO 2
INCHES SOUTHEAST.

SNOW AND SLEET WILL TAPER OFF THURSDAY MORNING, BUT THE NORTH
WINDS WILL NOT. IN FACT, LOOK FOR WIND CHILLS IN THE SINGLE DIGITS
TO AROUND 10 DEGREES IN THE MORNING, AND ONLY REACH THE TEENS IN
THE AFTERNOON. EASTERN AREAS WILL REMAIN MOSTLY CLOUDY TOMORROW,
WHILE SKIES SHOULD BECOME PARTLY CLOUDY OVER THE WEST.

COLD HIGH PRESSURE BUILDS OVER THE AREA THURSDAY NIGHT, BRINGING
ALONG FRIGID COLD TEMPERATURES BY SUNRISE FRIDAY. LOWS ARE
EXPECTED TO RANGE FROM THE SINGLE DIGITS OVER THE EXTREME NORTH TO
THE MIDDLE TEENS SOUTH. SNOW-COVERED SPOTS NEAR THE KENTUCKY
BORDER COULD SEE READINGS DROP TO ZERO.

TEMPERATURES FINALLY START TO WARM INTO THE 30S ON FRIDAY.

19

LONG TERM...LOOK FOR HIGH PRESSURE TO MOVE ACROSS MIDDLE
TENNESSEE OVER THE WEEKEND, ALLOWING FOR WARMER TEMPERATURES AND
DRY WEATHER. THE ECMWF BRINGS A GULF OF MEXICO SYSTEM ONSHORE AT
THE START OF NEXT WEEK THAT WILL PRODUCE A SLIGHT CHANCE OF
PRECIPITATION TO PARTS OF MIDDLE TENNESSEE, BUT THE BULK OF THE
ACTIVITY WITH THIS SYSTEM WILL REMAIN TO OUR SOUTH AND EAST.
TEMPERATURES WILL CONTINUE TO WARM THROUGHOUT THE WEEK, WITH THE
NEXT WEATHER-PRODUCER LATER IN THE WEEK AS A SECOND ONSHORE SYSTEM
TAKES A MORE NORTHERLY TRACK TOWARD THE MID STATE.

08

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING FROM 6 PM THIS EVENING TO NOON CST THURSDAY
FOR TNZ008>011-027>034-064>066.

WINTER STORM WARNING FROM 9 PM THIS EVENING TO NOON CST THURSDAY
FOR TNZ056>063-075-077>080-093>095.

WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO 9 AM CST
THURSDAY FOR TNZ005>007-023>026.

&&

$$
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