Area Forecast Discussion
Issued by NWS Nashville, TN

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FXUS64 KOHX 250938
AFDOHX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NASHVILLE TN
338 AM CST SUN JAN 25 2015

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT.

THE LIGHT SNOW WE HAD 24 HOURS AGO MELTED YESTERDAY AS SUNSHINE
AND MILD WSW WINDS PUSHED HIGH TEMPS INTO THE 40S TO LOWER 50S.
EARLY THIS MORNING...TRANQUIL CONDITIONS WERE IN PLACE WITH CLEAR
TO PARTLY CLOUDY SKIES AND TEMPS FROM THE LOWER 30S EAST TO AROUND
40 WEST. TEMPS WILL NOT CHANGE MUCH THROUGH THE REST OF THE NIGHT
THANKS TO A LIGHT S WIND AND INCREASING HIGH CLOUDS.

FOR TODAY THROUGH TONIGHT...A VIGOROUS LOW PRESSURE SYSTEM FROM
THE MID MS VALLEY WILL SWING DOWN ACROSS TN. AS THIS SYSTEM
APPROACHES...CLOUDS WILL INCREASE AND SHOWERS WILL
DEVELOP...ESPECIALLY THIS AFTERNOON. SSW SURFACE WINDS WILL BRING
IN SOME MILD AIR AHEAD OF THIS SYSTEM...WITH TEMPS CLIMBING INTO
THE LOWER 50S EARLY THIS AFTERNOON...BUT FALLING BACK AS SHOWERS
BECOME WIDESPREAD LATE IN THE AFTERNOON. THIS SYSTEM CONTAINS VERY
COLD AIR ALOFT...WITH 500 MB TEMPS NEAR -30 DEG C...SO MID LEVEL
LAPSE RATES WILL BECOME QUITE STEEP THIS AFTERNOON. THIS
INSTABILITY COMBINED WITH FREEZING LEVELS UNDER 7 KFT...WILL BRING
THE POTENTIAL FOR SOME THUNDERSTORMS...WITH A FEW PRODUCING SMALL
HAIL.

SHOWERS ARE LIKELY TO CONTINUE THROUGH THIS EVENING...WITH SOME
RUMBLES OF THUNDER STILL POSSIBLE THROUGH 9 PM OR SO. LATER
TONIGHT...AFTER MIDNIGHT...SHOWERS WILL BE DECREASING IN COVERAGE.
AT THE SAME TIME...COLDER AIR WILL BE MOVING IN...RESULTING IN A
SCATTERED RAIN AND SNOW MIX. LOW LEVEL TEMPS LOOK TOO WARM FOR
MUCH ACCUMULATION POTENTIAL...BUT WE CERTAINLY CANNOT RULE OUT A
QUICK DUSTING AROUND DAYBREAK MONDAY...ESPECIALLY FOR THE HIGHLAND RIM
AND PLATEAU.

FOR MONDAY THROUGH MONDAY NIGHT...TEMPERATURES WILL BE CHILLY WITH
MOSTLY CLOUDY SKIES. ANOTHER WEAK SHORTWAVE MAY KEEP FLURRIES OR
LIGHT SNOW SHOWERS GOING THROUGH MONDAY AND MONDAY NIGHT FOR THE
EASTERN THIRD OF OUR AREA.

13

MODELS ARE IN PRETTY GOOD AGREEMENT WITH THEIR HANDLING OF THE FIRST
PART OF THE EXTENDED FORECAST, GIVING US A SUNNY WEDNESDAY WITH
HIGHS IN THE MID 40S TO LOWER 50S, FOLLOWED BY THE APPROACH OF A
NORTHWESTERLY FLOW SHORTWAVE WEDNESDAY NIGHT AND PASSAGE OF THE
SHORTWAVE BY THURSDAY NIGHT. ECMWF TAKES SOME TIME TO DIG THE
SHORTWAVE AS IT APPROACHES OUR AREA AND IS A BIT SLOWER WITH THE
EASTWARD PROGRESSION. HENCE, IT HOLDS ON TO THE CHANCE FOR PRECIP IN
THE MID STATE A BIT LONGER. HAVE TENDED TO GO WITH A CONSALL/ECMWF
BLEND WITH PRECIP PATTERN, GIVING US A CHANCE FOR RAIN ON THURSDAY AND
A CHANCE FOR PRECIPITATION AT LEAST OVER THE EASTERN
TWO-THIRDS OF OUR FA THURSDAY NIGHT. THERE SHOULD BE ENOUGH COLD AIR
WITH THIS SYSTEM TO ALLOW FOR A POSSIBLE WINTRY MIX OVER NORTHERN
AND EASTERN PARTS OF THE MID-STATE BEFORE PRECIP ENDS LATE THUR NIGHT.

FRIDAY LOOKS DRY AS A COOL HIGH PRESSURE SYSTEM BUILDS EASTWARD OUT
OF THE PLAINS AND INTO THE OHIO AND TENNESSEE VALLEY.

AS WE HEAD INTO NEXT WEEKEND, MODELS START DIVERGING A BIT IN REGARD
TO THE HANDLING OF A SHORTWAVE THAT DROPS SOUTHWARD OUT OF CANADA
AND DEEPENS OUR ENDURING EASTERN U.S. TROUGH. INFLUENCE OF 500MB
CUT-OFF LOW OFF BAJA CALIFORNIA MAKES IT DIFFICULT TO DETERMINE HOW
RAPID THE ASSOCIATED BAND OF CLOUDS WILL LINGER OVER OUR AREA. HAVE
GONE SOMEWHAT WITH A GFS/ECMWF COMPROMISE AND PUSHED CLOUDS AND
CHANCE FOR ANY LIGHT PRECIP SOUTHWARD WITH TIME, BUT NOT AS RAPIDLY
AS FORECAST BY THE ECMWF. THE ARRIVAL OF THE COLDEST AND DRIEST AIR
MAY NOT COME IN WITH THAT INITIAL SHORTWAVE, AND HAVE THEREFORE KEPT
TEMP AND DEW POINT DROP MORE MODEST THAN WHAT IS FORECAST BY ECMWF.

EVEN THOUGH IT DEFINITELY LOOKS LIKE A TREND TOWARD COLDER AIR WITH
LOWER DEW POINTS BY THE END OF THE EXTENDED PERIOD, JUST CAN`T GO
WHOLE HOG WITH SOME OF THE COLDEST MODEL SOLUTIONS JUST YET.

19

&&

.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE      53  33  39  32 /  90  70  10  10
CLARKSVILLE    51  30  40  32 /  90  60  05  10
CROSSVILLE     50  32  37  28 /  60 100  20  20
COLUMBIA       53  33  41  32 /  80  60  10  10
LAWRENCEBURG   54  33  41  32 /  60  60  10  10
WAVERLY        52  32  41  31 /  90  60  05  05

&&

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

&&

$$






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