Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 012057
AFDOHX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
257 PM CST SUN MAR 1 2015

.DISCUSSION...

LIGHT RAINS CONTINUE TO SWEEP ACROSS THE MID-STATE THIS AFTERNOON AS
A WEAK COLD FRONT APPROACHES FROM THE NORTHWEST.  CURRENTLY DRAPED
FROM CINCINNATI TO MEMPHIS...THIS COLD FRONT WILL BREAK INTO MIDDLE
TENNESSEE OVER THE NEXT COUPLE OF HOURS AND HELP TEMPERATURES START
TO FALL OFF...ESPECIALLY OVER THE NORTHWESTERN HALF OF THE AREA.
ADDITIONAL SHORTWAVES WILL TRAVERSE THE FRONT THIS EVENING...AND AS
THE RAIN TRIES TO COME TO AND END ACROSS THE NORTH AFTER
MIDNIGHT...SUB-FREEZING SURFACE TEMPERATURES AND A DEEP ELEVATED WARM
LAYER WILL OPEN UP SEVERAL AREAS IN THE MID-STATE FOR SOME
FREEZING DRIZZLE. QPFS REMAIN VERY LIGHT ON THE BACK SIDE OF THIS
SYSTEM...AND WITH THIS AFTERNOON`S TEMPERATURES REACHING THE LOW
TO MIDDLE 40S...I DON`T SEE MUCH IN THE WAY OF IMPACTS. IF WE DO
SEE ANY ICE ACCRETION IT MIGHT BE A HUNDREDTH OR TWO ON ELEVATED
SURFACES AND TREE LIMBS. ROAD SURFACES SHOULD REMAIN UNIMPACTED.
FOR THIS REASON...PLUS A LOWER CONFIDENCE ON THERE BEING ENOUGH
QPF FOR ICE ACCRETION...WILL NOT ISSUE A WINTER WEATHER ADVISORY
ATTM. IF TRENDS LEAN THAT WAY THIS EVENING...WE MAY NEED TO ISSUE
ONE PRIOR TO MIDNIGHT...ESPECIALLY IF QPFS GET ANY HIGHER THAN THE
CURRENT HUNDREDTH OR TWO.

A GENERALLY WET PATTERN FOR THE NEXT COUPLE OF DAYS CONTINUES MONDAY
WITH MORE LIGHT RAIN AS A WARM FRONT LIFTS BACK TO THE NORTH.  THE
WARM FRONT IS PART OF A LATE-WINTER SYSTEM THAT MAY VERY WELL BRING
US SOME ISOLATED THUNDER TUESDAY AS THE LOW PASSES WELL OFF TO THE
NW OF US.  IT WILL BE BREEZY TUESDAY AS WELL...ESPECIALLY IN THE
EVENING AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF FRONTAL PASSAGE.

MODELS ARE NOT IN GOOD AGREEMENT IN THE TIMING OF THE FRONT MOVING
THROUGH THE MID-STATE ATTM.  NAM IS SLOWEST...GFS IS THE FASTEST AND
THE EURO SITS SOMEWHERE IN THE MIDDLE.  OVERALL...I HAVE GONE WITH
SOMETHING SIMILAR TO THE EURO TIMING REGARDING FRONTAL PASSAGE.
POST-FRONTAL PASSAGE COULD VERY WELL BE THE STORY OF THIS SYSTEM
THOUGH.  MODELS ARE...AND HAVE BEEN IN GOOD AGREEMENT WITH A LARGE
AMOUNT OF LIFT BEHIND THE FRONT ASSOCIATED WITH WHAT SEEMS TO BE AN
EXTREMELY STRONG UPPER LEVEL JET.  WITH MIDDLE TN RESIDING IN THE
RIGHT ENTRANCE REGION OF THIS 140-170 KT JET...MODELS CONTINUE TO
SPIT OUT AN INORDINATE AMOUNT OF QPF IN A ENVIRONMENT SOLIDLY
SUPPORTIVE OF SNOW ON THE BACK SIDE OF WEDNESDAY`S FRONT. IF WE
WENT WITH A 10 TO 1 RATIO...AND EVEN ACCOUNTED FOR LATENT HEAT
RELEASE FROM TUESDAY NIGHT`S LIQUID RAINFALL...WE WOULD BE IN LINE
FOR 4 TO 6 INCHES OF SNOW ACROSS A GOOD PORTION OF THE MID-STATE.
THE GOOD NEWS IS...THIS SET UP IS TYPICALLY NOT CONDUCIVE TO THAT
KIND OF SNOW ACCUMULATION. WE USUALLY ONLY GET THOSE KIND OF SNOW
TOTALS WITH A SURFACE LOW PASSING US TO THE SOUTH...MUCH LIKE LAST
WEEK. THAT SAID...DUE TO MODEL CONSISTENCY...I HAVE TO START
TALKING ABOUT MINOR SNOW ACCUMULATIONS WEDNESDAY AND WEDNESDAY
NIGHT BUT I`M NOT GOING TO ATTACH ANY MORE THAN 1-2 INCHES TO THE
FORECAST ATTM. PLENTY MORE TO COME REGARDING THIS SYSTEM.
EXPECTATION IS FOR THE MODELS TO FINALLY REALIZE THEY`RE OVERDOING
THE QPF AND BACK OFF OVER THE NEXT SEVERAL RUNS.

A DECENTLY STRONG SURFACE RIDGE PUSHES IN HERE THURSDAY BEHIND THE
FRONT.  THIS IS GOING TO DROP TEMPERATURES OFF FAIRLY STEEPLY
THURSDAY AND THURSDAY NIGHT...BUT MUCH DRIER CONDITIONS SHOULD BRING
PLENTY OF SUNSHINE...SOMETHING WE DIDN`T REALLY SEE LAST WEEK...SO
EVEN IF WE SEE SNOW WEDNESDAY...WE SHOULD BE ABLE TO GET RID OF IT
PRETTY QUICKLY AS TEMPERATURES REBOUND INTO THE 40S AND 50S FRIDAY
AND SATURDAY.

UNGER

&&

.AVIATION...18Z TAF DISCUSSION.

FRONTAL BOUNDARY WILL WORK THROUGH THE AREA TODAY AND WINDS WILL
SHIFT TO NORTHERLY BETWEEN 00Z AND 06Z. THEREFORE...RAINFALL AND
LOW IFR CIGS WILL BE NEARLY CONTINUOUS INTO THIS EVENING. LATE
TONIGHT...AS TEMPS FALL TO NEAR FREEZING...THERE COULD BE SOME
PATCHY LIGHT FRZ RA BETWEEN 08Z AND 14Z. OTW...IMPROVING
CONDITIONS AFT 14Z WITH CIGS RISING.

&&

.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE      33  46  38  63 /  70  40  40  80
CLARKSVILLE    28  42  35  60 /  60  30  50  80
CROSSVILLE     31  43  37  56 /  70  50  40  80
COLUMBIA       34  43  39  64 /  80  50  50  70
LAWRENCEBURG   34  43  41  64 /  80  50  50  70
WAVERLY        31  44  39  62 /  60  40  50  80

&&

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

&&

$$

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