Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 022145
AFDOHX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
345 PM CST MON MAR 2 2015

.DISCUSSION...

A RELATIVELY QUIET DAY HAS ENSUED ACROSS MIDDLE TN TODAY WITH LOTS
OF SUNSHINE AND TEMPERATURES CLIMBING WELL INTO THE 40S FOR MOST.
THIS IS A WELCOMED CHANGE FROM WHAT WE HAVE BEEN SEEING OVER THE
LAST COUPLE OF WEEKS AND WHILE IT WILL BE YET WARMER ON
TUESDAY...THE PRECIPITATION CHANCES WILL BE ON THE INCREASE.
YESTERDAY`S COLD FRONT WHICH IS OFF TO OUR SOUTH WILL LIFT BACK
NORTHWARD TONIGHT AS A WARM FRONT.  THIS WILL PRODUCE A SURGE IN DEW
POINTS AND TEMPERATURES...PROVIDING FOR AFTERNOON HIGHS IN THE LOW
TO MIDDLE 60S TUESDAY.  UNFORTUNATELY AS WE KNOW ALL TOO WELL...A
SURGE IN TEMPERATURES THIS TIME OF YEAR USUALLY COMES WITH
CONSEQUENCES.  THIS IS NO DIFFERENT.  SHOWERS WILL RETURN BY
TOMORROW MORNING AND SCATTERED THUNDERSTORMS WILL LIKELY MAKE AN
APPEARANCE AS WELL.  INSTABILITIES ARE VERY LOW AND WHILE DEEP LAYER
SHEAR IS VERY HIGH...NO REAL ORGANIZATION IS EXPECTED...SO NO SEVERE
WEATHER IS ANTICIPATED AT THIS TIME.

THE ASSOCIATED COLD FRONT WITH THIS SYSTEM WILL APPROACH OUR
NORTHWEST COUNTIES WEDNESDAY MORNING AND AS IT DOES...A STRONG
UPPER LEVEL JET IS EXPECTED TO DEVELOP JUST OFF TO OUR NORTH.  THE
DYNAMICS CREATED BY THIS JET ARE GOING TO BE A MAJOR PLAYER IN
POST-FRONTAL QPF DEVELOPMENT WEDNESDAY.  1 TO 3 INCHES OF LIQUID
PRECIP ARE EXPECTED PRIOR TO ANY OF THE COLD AIR GETTING INTO MIDDLE
TN.  THE COMBINATION OF THIS RAINFALL AND MELTING OF PREVIOUS
SNOW/ICE FROM LAST WEEK COULD SPELL SOME LOCALIZED FLOODING
CONCERNS.  FOR THIS REASON...WE HAVE POSTED A FLOOD WATCH FOR
TUESDAY NIGHT THROUGH WEDNESDAY AFTERNOON. ADDITIONAL CONCERNS
WILL LIKELY REAR THEIR HEAD BY THE END OF THE WEEK AS WEDNESDAY`S
WINTER STUFF MELTS.  NOW...THE COLD STUFF.

AN INITIALLY SHALLOW LAYER OF COLD AIR WILL FILTER INTO THE STATE
FROM THE NORTHWEST STARTING LATE WEDNESDAY MORNING.  BECAUSE OF THIS
SHALLOW LAYER OF COLD AIR AND A DEEP LAYER OF WARM AIR JUST ABOVE
IT...FORECAST SOUNDINGS THROUGH THIS TIME FRAME ARE INDICATIVE OF A
TRANSITION FROM THE LIQUID PRECIP TO A COUPLE OF HOURS OF FREEZING
RAIN...BEFORE A CHANGE OVER TO SLEET FOR SEVERAL HOURS...AND THEN TO
ALL SNOW FOR SEVERAL MORE HOURS.  IF THERE`S ANY GOOD NEWS...IT`S
THAT THE LOW 60S TEMPERATURES FROM TUESDAY AND TUESDAY NIGHT WILL
PLAY A ROLE IN KEEPING MUCH ICE FROM DEVELOPING BEFORE THE CHANGE
OVER TO SLEET. THE DOWNSIDE...POST-FRONTAL QPFS ARE STILL WHAT
SEEM TO BE RIDICULOUSLY HIGH FOR THIS TYPE OF SYSTEM. THESE POST-
FRONTAL WINTER SYSTEMS FOR MIDDLE TN USUALLY ONLY YIELD 1 TO 2
INCHES AT THE MOST...BUT WITH THE FACT THAT WE HAVE BEEN IN AN
UNUSUAL PATTERN FOR AWHILE NOW...THESE UNUSUALLY HIGH QPFS MAY NOT
BE TOO OUT OF LINE. I MAINTAIN THAT THEY ARE STILL A LITTLE TOO
HIGH...BUT EVEN STAYING ON THE CONSERVATIVE SIDE OF THE SNOW/SLEET
AMOUNT YIELDS 3 TO 6 INCHES OF SLEET AND SNOW. THE HIGHEST AMOUNTS
LOOK LIKE THEY SHOULD BE FOR AREAS ALONG AND NORTH OF I-40...BUT
I`M STILL HOLDING ONTO 2 TO 3 INCHES ALONG THE ALABAMA STATE LINE.
NEEDLESS TO SAY...THESE KINDS OF SNOW AND SLEET TOTALS WILL HAVE
MAJOR TRAVEL IMPACTS FOR THE MID-STATE...NOT ONLY WEDNESDAY AND
WEDNESDAY NIGHT...BUT THROUGH THURSDAY AND INTO THE DAY ON FRIDAY.
THE CAA BEHIND THIS FRONT IS GOING TO BE VERY INTENSE. EVEN WITH
PLENTY OF SUNSHINE THU/FRI/SAT...IT LOOKS LIKE HIGHS ON THURSDAY
MAY ONLY REACH 30 AT THE MOST...AND SINGLE DIGIT TEMPERATURES
THURSDAY NIGHT ARE LOOKING VERY LIKELY FOR A GOOD CHUNK OF
NORTHERN MIDDLE TN. THIS MEANS ANYTHING THAT REMAINS ON AREA
ROADWAYS...ESPECIALLY LESS TRAVELED SECONDARY ROADS...IS GOING TO
CONTINUE TO CAUSE PROBLEMS.

THE QUESTION WAS RAISED TODAY ABOUT OUR LAST COUPLE OF SYSTEMS
AND HOW THE ELEVATED WARM LAYER STUCK AROUND LONGER CREATING MORE
ICE THAN SNOW/SLEET. THIS IS NOT OUT OF THE QUESTION AND WILL NEED
TO BE MONITORED...BUT WITH THIS SET UP...THIS IS LESS LIKELY TO
OCCUR AND IS WHY WE ARE FOCUSING MORE ON THE SLEET AND SNOW
POTENTIAL VS THE ICE POTENTIAL THIS TIME AROUND.

EXTENDED GUIDANCE IS SHOWING A BIT OF A WARM UP BY THE END OF THE
UPCOMING WEEKEND WITH TEMPERATURES TRYING TO GET BACK TOWARDS NORMAL
BUT MODEL DIFFERENCES INCLUDE A EURO GULF SYSTEM SWEEPING IN SUNDAY
FOR US...WHICH THE GFS IS CURRENTLY KEEPING COMPLETELY IN THE GULF
KEEPING US RAINFREE.  WILL KEEP A VERY SMALL POP CHANCE FOR SUNDAY
ATTM.

UNGER

&&

.AVIATION...18Z TAF DISCUSSION.

MAINLY VFR THIS AFTERNOON FOR KBNA AND KCKV WITH MVFR/VFR AT KCSV.
CLOUD DECK OVER THE PLATEAU AT KCSV HAS BEEN HANGING AROUND A BIT
LONGER THAN MODEL GUIDANCE SUGGESTED. PER VIS SAT...CLOUD DECK IS
SLOWLY ERODING FROM THE NORTH AND MAY BRING KCSV TO VFR THIS
AFTERNOON. CLOUDS SHOULD RETURN THIS EVENING AS WAA MOVES INTO
THE REGION. MVFR CIGS SHOULD MOVE IN AFTER 02Z FOR KBNA AND
KCKV...WITH IFR CIGS FOR ALL TERMINALS AFTER 12Z TOMORROW MORNING.
IFR CIGS MAY IMPACT KCSV A BIT EARLIER THAN THE OTHER TERMINALS AT
AROUND 06Z-09Z. RAIN CHANCES WILL ALSO MOVE IN OVERNIGHT AND
IMPACT ALL TERMINALS BY 12Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE      38  63  47  50 /  50  70 100 100
CLARKSVILLE    35  60  38  39 /  50  80 100 100
CROSSVILLE     36  56  54  57 /  50  80 100 100
COLUMBIA       39  64  54  56 /  50  70 100 100
LAWRENCEBURG   40  64  56  58 /  50  60 100 100
WAVERLY        38  62  42  44 /  50  80 100 100

&&

.OHX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON FOR
TNZ005>011-023>034-056>060-062>066.

WINTER STORM WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
MORNING FOR TNZ005>011-023>034-056>066-075-077>080-093>095.

&&

$$

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