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000
FXUS64 KOHX 042121
AFDOHX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
321 PM CST WED DEC 4 2013

.DISCUSSION...

TONIGHT - THURSDAY NIGHT...

HAVE DECREASED THE POTENTIAL FOR LIGHT RAINFALL THIS EVENING
ACROSS THE MID STATE...WITH ONLY A SLIGHT CHANCE ACROSS NW
PORTIONS OF THE MID STATE BEGINNING IN THE MID EVENING HRS.
HOWEVER...STILL EXPECTING A SFC FRONT TO ENTER THE MID STATE AFTER
MIDNIGHT...AND WITH UPPER LEVEL FLOW BECOMING INCREASINGLY
SWLY...THIS WILL SET THE STAGE FOR THE MID STATE TO EXPERIENCE
WIDESPREAD SHWRS ALONG WITH ISO/SCT TSTMS ON THU ALONG AND AHEAD
OF THE SFC FRONT...AS UPPER LEVEL TROUGH REMAINS WELL TO OUR WEST
AND ISENTROPIC LIFT CONTINUES TO GENERATE SIGNIFICANT LIQUID
PRECIPITATION POTENTIAL. THIS SFC FRONT WILL MOVE SLOWLY EAST
ACROSS THE MID STATE ON THU AND INTO EASTERN PORTIONS OF THE MID
STATE THU NIGHT. HOWEVER...DESPITE FRONT MOVING EWD...CONTINUED
UPPER LEVEL SWLY FLOW AND ABOVE MENTIONED ISENTROPIC LIFT WILL
PROVIDE FOR SHWRS ACROSS THE MID STATE THRU THU NIGHT. RAINFALL
COULD BE HEAVY AT TIMES THU AND INTO THU NIGHT ALSO. TOTAL
RAINFALL AMOUNTS OF AROUND TWO INCHES WILL BE POSSIBLE ACROSS NW
PORTIONS OF THE MID STATE WITH AROUND ONE AND ONE QUARTER INCHES
ACROSS SRN AND ERN PORTIONS...INCLUDING THE PLATEAU. AS FOR
TEMPS...WILL BE TAILORING THEM ACCORDINGLY WITH THE FRONTAL
MOVEMENT INTO THE MID STATE LATE TONIGHT...WITH SOME UPPER 50S TO
LOWER 60S POSSIBLE ACROSS NW PORTIONS OF THE MID STATE...BUT THE
REST OF THE MID STATE SHOULD GENERALLY REMAIN IN THE LOW TO MID
60S. FOR THU...EXPECT MAYBE A SLIGHT WARMUP IN TEMPS AHEAD OF THE
FRONT ACROSS ERN PORTIONS OF THE MID STATE...BUT MOST LOCATIONS
WILL EXPERIENCE STEADY TEMPS FROM OVERNIGHT LOWS TONIGHT. COLD AIR
FINALLY BEGINS TO WORK INTO THE MID STATE THU NIGHT...BUT AT THIS
TIME BELIEVE THAT ALL LOCATIONS WILL EXPERIENCE LIQUID
PRECIPITATION WITH LOWS IN THE MID 30S NW TO MID 40S PLATEAU.

31

FRIDAY - WEDNESDAY...

...AMPLE RAINFALL AND HAZARDOUS WINTRY WEATHER EXPECTED DURING THIS
TIME PERIOD...

A COLD BUT AMPLE RAINFALL WILL BE AFFECTING AT LEAST THE WESTERN
HALF OF THE CWA FRIDAY MORNING. TEMPS ALOFT WILL STAY WARM...BUT
SURFACE TEMPS WILL START TO FALL FIRST ACROSS THE NORTHWESTERNMOST
COUNTIES RESULTING IN A CHANGEOVER TO FIRST FREEZING RAIN THEN
MOST LIKELY SLEET. THE QUESTION IS WHEN. THE 12Z NAM WAS VERY WARM
YESTERDAY AND IS THE COLDEST TODAY SIMILAR TO THE EURO. THE GFS
SEEMS TO BE THE MIDDLE OF THE ROAD WITH CONSISTENCY...AND THE SREF
IS A BIT ON THE FASTER/COLDER SIDE. WAS HESITANT TO GO TOO FAR
EAST WITH THE WATCH JUST YET...BUT THE BEST CHANCE AT ICE OR SLEET
ACCUMULATIONS HAVE BEEN INCLUDED IN THE WATCH...MAINLY AREAS
WEST/NORTHWEST OF THE NASH METRO REGION. THIS MAY NEED TO BE
EXPANDED EASTWARD SHOULD THE NEXT SET OF MODEL DATA COME IN WITH A
COLDER TREND. RIGHT NOW...HAVE A TRANSITION TO FZRA/IP LATE
MORNING AND SLOWLY SPREADING EASTWARD THROUGHOUT THE DAY FRIDAY.
THINKING AROUND THE 00Z SATURDAY TIME FRAME...A CHANGEOVER COULD
OCCUR AROUND THE I-65 CORRIDOR. ICE/SLEET ACCUMULATIONS OVER THE
FAR NORTHWEST COUNTIES UNDER THE WATCH COULD BE UP TO ONE HALF
INCH/ONE INCH...WITH THE HIGHEST AMOUNTS LIKELY OVER STEWART
COUNTY. LESSER ADVISORY-TYPE AMOUNTS ARE EXPECTED DOWNSTREAM
(INCLUDING NASHVILLE) BUT WILL STILL POSE A MINOR THREAT TO
TREE/POWERLINE ACCUMULATION AND POSSIBLY TO ROAD CONDITIONS AS
WELL. THE GROUNDS SHOULD BE WARM THAT ICE MAY NOT ACCUMULATE ON
ROADWAYS BUT SHOULD SLEET START TO ACCUMULATE...THAT WOULD LOWER
GROUND TEMPS FASTER AND CAUSE AN INCREASED TRAVEL CONCERN. THE
GOOD NEWS IS THAT PRECIP EXITS QUICKLY AFTER MIDNIGHT THAT MAYBE A
QUICK LIGHT SNOW OR FREEZING DRIZZLE WILL BE POSSIBLE BEFORE WE
DRY OUT AROUND 6Z. LOCATIONS NEAREST THE PLATEAU WILL BE THE
WARMEST THROUGHOUT THE WEEKEND AND REALLY DO NOT HAVE A WINTRY
WEATHER THREAT.

ONCE THAT SYSTEM MOVES EAST...ANOTHER SYSTEM OVER THE GULF WILL
QUICKLY RETURN PRECIPITATION TO THE REGION STARTING LATE SATURDAY
NIGHT. HIGHS SATURDAY WILL HOVER AT OR BELOW FREEZING OVER NW
MIDDLE TN...SO ONSET OF PRECIP SAT NIGHT MAY POSE ANOTHER THREAT
AS WARM AIR OVERRIDES FREEZING/POSSIBLY SUB-FREEZING SFC TEMPS.
PRECIP ONSET OVER NW AREAS WILL THUS BE FREEZING RAIN MOST LIKELY
WITH A COLD RAIN FURTHER SOUTH AND EAST. THE GOOD NEWS IS THAT ANY
ICE ACCUMS WILL LIKELY MELT DURING THE MORNING-DAYTIME SUNDAY AS
TEMPERATURES CONTINUE TO RISE THROUGHOUT THE DAY. BUT THERE COULD
BE A QUICK TENTH TO MAYBE AS HIGH AS ANOTHER QUARTER INCH OF ICE
ACCUMS BY SUNDAY MORN OVER THE NW COUNTIES. A PLUME OF MOISTURE
WILL THEN RESULT IN 1-2 INCHES OF RAIN SUNDAY THROUGH SUNDAY NIGHT
BEFORE THE SYSTEM EXITS TO OUR EAST. OUR EASTERNMOST COUNTIES WILL
RECEIVE THE MOST RAINFALL...WITH LOCALLY 3 INCH AMOUNTS POSSIBLE.
WITH THE THRS-FRI RAINFALL AND SUN-MON RAINFALL...RIVER FLOODING
COULD BECOME A PROBLEM BY LATE IN THIS FORECAST PERIOD.

BY MONDAY WE SHOULD FINALLY START TO DRY OUT ACROSS THE AREA.
TEMPS WILL ALSO PLUMMET AS A COLD HIGH PRESSURE SETTLES INTO THE
AREA. BY TUESDAY AND TUESDAY NIGHT...HIGHS WILL ONLY BE IN THE
UPPER 20S TO MID 30S...WITH LOWS IN THE TEENS BUT WOULD EXPECT A
FEW SINGLE DIGITS TO POP UP EARLY WED MORN.

AL

&&

.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE      63  63  39  42 /  60 100 100 100
CLARKSVILLE    59  59  33  36 /  60 100  90 100
CROSSVILLE     62  67  46  54 /  40 100 100 100
COLUMBIA       62  63  39  43 /  50 100 100 100
LAWRENCEBURG   62  64  39  45 /  50 100 100 100
WAVERLY        60  62  33  38 /  60 100  90 100

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
FOR TNZ005>007-022>026-056-057.

&&

$$