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000
FXUS64 KOHX 070456
AFDOHX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
1056 PM CST FRI DEC 6 2013

.AVIATION 06Z DISCUSSION...
PRECIPITATION HAS NOW MOVED EAST OF THE AREA WITH LOW CLOUDINESS
REMAINING. LOW CIGS TO PREVAIL THROUGH 12Z BUT CONDITIONS WILL
IMPROVE FROM THAT POINT UNTIL 00Z. THEN...ANOTHER SLUG OF SFC
ENERGY WILL DEVELOP AND SPREAD PRECIPITATION BACK ACROSS THE AREA
TOWARD THE TAIL END OF THE TAF PD. THERMAL PROFILES DO SUPPORT
ANOTHER ROUND OF -FZRA FOR CKV AND BNA WITH A -FZRA/RA MIX AT CSV.

&&

.PREV DISCUSSION... /ISSUED 905 PM CST FRI DEC 6 2013/

UPDATE...
LARGE AREA OF PCPN NOW EAST OF THE PLATEAU...WITH REMAINING PCPN
JUST A THIN BAND ASSOCIATED WITH BOUNDARY ON LEADING EDGE OF COLDER
AIR. TEMPERATURES HAVE REMAINED JUST ABOVE FREEZING AHEAD OF
BOUNDARY AND OVERALL THAT HAS HELPED KEEP ICING MINIMAL...EXCEPT
FOR THE EXTREME NORTHWEST.

LATEST MODELS/TRENDS SHOWING THE POSSIBILITY OF PATCHY -ZL FOR A
SHORT TIME BEHIND BOUNDARY AS IT MOVES EAST BUT IT CURRENTLY DOES
NOT LOOK TO CAUSE MUCH ADDITIONAL PROBLEM. ROADS HOWEVER REMAIN
WET AND WITH TEMPS BEHIND BOUNDARY ON THEIR WAY DOWN...SLICK SPOTS
LIKELY TO DEVELOP ESPECIALLY ON ELEVATED SURFACES.

WITH PCPN BASICALLY OVER WILL CANCEL WSW AT 03Z...BUT WE WILL
CONTINUE TO HIGHLIGHT ROAD HAZARD SITUATION. WILL ALSO
HAVE TO KEEP EYE ON -ZL SITUATION SHOULD IT FLARE UP LONGER THAN
ANTICIPATED.

MODELS CONTINUE TO SHOW POTENTIAL FOR ADDITIONAL WINTER WEATHER
TOMORROW NIGHT.

PREV DISCUSSION... /ISSUED 550 PM CST FRI DEC 6 2013/

AVIATION 00Z DISCUSSION...
THE DEEPER MOISTURE IS ON THE DECREASE ACROSS THE MID STATE AS
THIS FIRST SYSTEM IS BEGINNING TO PULL EASTWARD. CONTINUOUS LIGHT
RAINFALL SHOULD CONTINUE ACROSS THE CSV AREA HOWEVER FOR THE NEXT
FEW HOURS.

AS THE SFC FREEZING LINE CONTINUES TO WORK TOWARD THE EAST AND
SOUTH...PERIODS OF -FZRA AND -FZDZ WILL BE POSSIBLE THROUGH AND
BEYOND 06Z. SOME ICE PELLETS WILL ALSO BE POSSIBLE. CIGS AND VSBYS
WILL IMPROVE AFT 12Z.

PREV DISCUSSION... /ISSUED 334 PM CST FRI DEC 6 2013/

SHORT TERM...(TONIGHT THROUGH SATURDAY)

AT 3 PM CST...FREEZING RAIN CONTINUED TO FALL OVER OUR FAR NORTHWEST
AREAS. RADAR AND SHORT RANGE MODELS INDICATE 3 OR 4 MORE HOURS OF
LIGHT TO MODERATE FREEZING RAIN...MIXED WITH SLEET...WITH RATES
AROUND 0.10 INCH/HR. THIS WILL CONTINUE TO INCREASE THE ICE LOAD ON
TREES AND POWER LINES...SO SOME POWER OUTAGES SHOULD BE EXPECTED
WITH ICE TOTALS AROUND UP TO ONE HALF INCH IN THE WARNING AREA.
ALSO...ROAD CONDITIONS WILL CONTINUE TO DETERIORATE WITH FALLING
TEMPERATURES THIS EVENING.

FOR THE ADVISORY AREA...INCLUDING NASHVILLE METRO...TEMPERATURES
ARE MOSTLY IN THE 33-35 RANGE AT 21Z...BUT SOME ICE WAS COLLECTING
ON TREES AND LINES AT THE HIGHER ELEVATIONS ALONG AND WEST OF
INTERSTATE 65. THE ADVISORY IS SET TO BEGIN AT 4 PM...WHICH
SHOULD LINE UP WITH THE START OF TRAVEL IMPACTS...BEGINNING WITH
ICE ON BRIDGES FROM PORTLAND DOWN TO JOELTON...FAIRVIEW AND
HOHENWALD. THEN CONDITIONS WILL WORSEN INTO THE EVENING...WITH
SLICK CONDITIONS SPREADING SOUTHEASTWARD ACROSS THE ADVISORY AREA
THROUGH THE EVENING RUSH HOUR.

BY 10 PM THIS EVENING...THE DYNAMIC SUPPORT FOR PRECIPITATION WILL
BE WEAKENING CONSIDERABLY...AND THE DEEP MOISTURE WILL BE MOVING
EASTWARD. PRECIPITATION WILL BE TAPERING OFF TO LIGHT
SLEET...FLURRIES AND FREEZING DRIZZLE. EVEN FOR LOCATIONS THAT ARE
NOT IN WARNINGS OR ADVISORIES...LEFTOVER MOISTURE WITH FALLING TEMPS
WILL LIKELY CAUSE SOME SLICK SPOTS TO DEVELOP OVERNIGHT.

REGARDING RAINFALL...STILL SOME HEAVY DOWNPOURS ON THE WAY WITH A
FEW RUMBLES OF THUNDER. A FEW SMALL STREAMS MAY RISE QUICKLY...BUT
NO MAJOR FLOOD PROBLEMS ARE EXPECTED. THE COVERAGE AND INTENSITY OF
ANY TSRA WILL DROP OFF QUICKLY AFTER 00Z.

DRY CONDITONS ARE EXPECTED SATURDAY...BUT MAINLY CLOUDY AND COLD.
HIGHS WILL ONLY REACH THE LOW TO MID 30S AND NORTH WINDS 10-20 MPH
WILL KEEP WIND CHILLS IN THE 20S.

13

LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)

OVERALL...SOUTHWEST FLOW ALOFT WILL CONTINUE SUNDAY/MONDAY WITH
LARGE TROUGH OVER THE WESTERN U.S. AND H5 RIDGE OVER THE ATLANTIC.
THE TROF WEAKENS AND PASSES THROUGH TN ON TUESDAY LEAVING A BRIEF
PERIOD OF ZONAL FLOW ON WEDNESDAY. SHOULD SEE A WEAK H5 RIDGE AXIS
LATE NEXT WEEK...AND MAYBE THE FIRST SIGNS OF YET ANOTHER LARGE
STORM SYSTEM APPROACHING BY NEXT WEEKEND.

THE OVERALL SCENARIO ABOVE SETS US UP FOR TWO MORE PRECIP
SITUATIONS. THE FIRST SHOULD DEVELOP LATE SATURDAY NIGHT AS AN
INVERTED TROUGH DEVELOPS ACROSS THE REGION. TEMPS WILL BE COLD
ENOUGH FOR A WINTERY MIX OR MAINLY FREEZING RAIN SATURDAY NIGHT
INTO EARLY SUNDAY. AMOUNTS SHOULD BE LIGHT...BELOW 1/4 INCH...BUT
FEEL IMPACTS CAN BEST BE HANDLED WITH POSSIBLE FUTURE ADVISORY
RATHER THAN A WATCH AT THIS TIME. THE GOOD NEWS IS THAT SLIGHTLY
WARMER AIR WILL MOVE IN...CHANGING PRECIP TO RAIN BY MID MORNING
ON SUNDAY. ADDITIONAL RAINS WILL OCCUR ALL SECTIONS DURING THE DAY
SUNDAY...WITH POTENTIALLY SIGNIFICANT RAINS MAINLY EASTERN MIDDLE
TN. THE PRECIP WILL END FROM WEST TO EAST VERY LATE SUNDAY NIGHT
INTO MONDAY.

THE OTHER PRECIP SITUATION IS THE POSSIBILITY OF ADDITIONAL WINTER
WEATHER...MAINLY SNOW...MONDAY NIGHT INTO TUESDAY. MODELS
GENERALLY AGREE ON MOVING THE H5 TROF AXIS TOWARD TN DURING THIS
TIME. IN RESPONSE...A NEW AREA OF LIGHT SNOW MAY DEVELOP AND
SPREAD INTO MIDDLE TN MONDAY NIGHT AND EARLY TUESDAY. BEST CHANCES
SHOULD BE OVER SOUTHERN AND EASTERN PORTIONS OF THE MID STATE BUT
WILL INCLUDE AT LEAST A SLIGHT MENTION FOR ALL AREAS.

THE REST OF THE WEEK SHOULD BE DRY BUT ANOTHER SYSTEM MAY BE ON
THE HORIZON BY NEXT WEEKEND.

&&

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

$$

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