Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 260254
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
854 PM CST SUN JAN 25 2015

.UPDATE...
LOWERED POPS...REMOVED THUNDER AND TWEAKED SKY GRIDS. OTHERWISE KEPT
REST OF THE FCST PARAMETERS AS IS.

&&

.DISCUSSION...
SFC LOW CONTINUES TO MOVE EAST AND IS CENTERED OVER KY WITH CDFNT
MOVING ACROSS THE HUN AREA. EXPECT THE CDFNT TO PUSH OUT OF THE CWA
ARND MIDNIGHT. THIS WILL ALLOW COLDER AIR TO FILTER ACROSS THE TN
VALLEY. WHATEVER MOISTURE IS LEFT OVER AFTER MIDNIGHT COULD PRODUCE
A RA/SN MIX BEGINNING ARND 09Z. ATTM NOT EXPECTING ANY SIGNIFICANT
ACCUMULATIONS...HOWEVER AS USUAL OUR NERN ZONES/PORTIONS OF SRN MID
TN MAY SEE SOME VERY LIGHT ACCUMULATIONS. NOT EXPECTING ANY MAJOR
TRAVEL PROBLEMS BUT THERE COULD BE A FEW SLICKS SPOTS ON ROADS
MONDAY MRNG...ESPECIALLY BRIDGES AND OVERPASSES.

07

&&

.AVIATION...
/ISSUED 540 PM CST SUN JAN 25 2015/
FOR 00Z TAFS...A COLD CORE UPPER LOW (ARND MINUS 25 C) CENTERED OVER
WRN KY/TN MAY PRODUCE ENOUGH INSTABILITY FOR A FEW -TSRA FOR THE NEXT
HOUR OR TWO. HOWEVER WITH LOSS OF DAYTIME HEATING THE CHC OF -TSRA
WILL CONTINUE TO DIMINISH. FOR NOW WILL NOT MENTION ANY THUNDER IN
TAFS. A CDFNT NOW OVER WRN TN SHOULD PASS THRU THE TAF SITES BY 06Z.
COLDER AIR WILL FILTER ACROSS THE TN VALLEY AFTER 06Z WHICH MAY
PRODUCE A RA/SN MIX BEGINNING ARND 09Z AND ENDING AS -SN/FLURRIES BY
15Z. ATTM LITTLE OR NO ACCUMULATIONS ARE EXPECTED ACROSS THE TAF
SITES. OTHERWISE VFR CONDITIONS THRU 05Z. BETWEEN 05Z AND 20Z MAINLY
MVFR CONDITIONS. AFTER 20Z EXPECT VFR CONDITIONS.

07

&&

.PREV DISCUSSION...
/ISSUED 300 PM CST SUN JAN 25 2015/
TEMPERATURES WARMED WELL INTO THE MID TO UPPER 50S TODAY...WHICH IS
WARMER THAN GUIDANCE SATURDAY WAS SHOWING. STARTING TO SEE SOME WIND
GUSTS 20-25MPH AS WELL AS THE PRE-FRONTAL TROUGH AND COLD FRONT
START TO TIGHTEN THE GRADIENT BETWEEN IT AND A DEPARTING HIGH. WITH
COLD ADVECTION COMING IN BEHIND THE TROUGH...THIS IS ALSO HELPING TO
KEEP GUSTY WINDS ACROSS THE AREA. THIS SHOULD CONTINUE OVERNIGHT
UNTIL THE FRONT PASSES THROUGH BY 12Z MONDAY. AS WELL...WILL LEAVE
SLIGHT CHANCE OF THUNDER IN THE FORECAST THROUGH THE EVENING. SOME
THUNDER IS OCCURRING TO THE WEST AND WITH MODERATELY STEEP LAPSE
RATES AND ELEVATED CAPE...CANNOT RULE OUT A RUMBLE OF THUNDER OR
TWO ACROSS THE AREA.

LIGHT RAIN WILL CONTINUE TO OVERSPREAD THE REGION FROM WEST TO EAST
THIS EVENING AND OVERNIGHT. WITH THE HIGH TEMPS WARMING MORE THAN
FORECAST...THINKING THAT THE WARMING TREND IN THE LOWS TONIGHT IS
PROBABLY GOING TO HOLD. MOSGUIDE CONTINUED TO BE THE COLDEST AS WAS
THE CASE YESTERDAY. I STILL UNDERCUT GUIDANCE BY A DEGREE BECAUSE
THAT UPPER LOW WILL BE SITTING RIGHT OVER US BETWEEN 6-12Z. THIS
COULD DYNAMICALLY COOL THE SURFACE MORE THAN GUIDANCE CAN PICK UP
ON. ONLY A FEW ELEVATED AREAS WILL BE AT 32 DEG WHILE MOST SITES WILL
BE 33-35 DEG TONIGHT.

MODERATE TO HIGH CONFIDENCE THAT PRECIP WILL STAY ALL RAIN UNTIL AT
LEAST 9Z MON AS PROFILES ARE WELL ABOVE FREEZING. THE ISSUE IS WHAT
HAPPENS THEN. UPPER LEVELS START TO COOL QUICKLY WITH THE SURFACE
LINGERING ABOVE FREEZING. AS THE SURFACE FALLS BELOW
FREEZING...MOISTURE ABOVE -10C IS NON EXISTENT MEANING SNOW CRYSTALS
ARE GOING TO BE TOUGH TO CREATE. HOWEVER...I HAVE SEEN FLURRIES STILL
COME OUT OF SOUNDINGS WITH NO UPPER LEVEL MOISTURE. 12Z GFS LEAVES
EVERYTHING WARM ENOUGH FOR RAIN...WHILE THE 12Z ECMWF DRIES THE AREA
OUT QUICKLY AND LASTLY THE NAM LEAVES ENOUGH MOISTURE IN AND A
SURFACE BELOW FREEZING TO MAKE FREEZING DRIZZLE A POSSIBILITY. WITH
THE WARMING OF THE MODELS AS TIME PROGRESSES...FEEL THAT THE BEST
FORECAST IS ALL RAIN THROUGH 9Z THEN A CHANCE OF RAIN WITH A SLIGHT
CHANCE OF SNOW AFTER...WITH THE EASTERN AREAS ENDING AS LIGHT SNOW OR
FLURRIES AFTER 12-14Z. THIS COULD MEAN LIGHT SNOW ACCUMULATIONS IN
HIGHER ELEVATIONS. DO NOT HAVE ENOUGH CONFIDENCE IN ACCUMULATING SNOW
OR FREEZING DRIZZLE TO ISSUE ANY WINTER PRODUCTS AT THIS TIME BUT
THIS WILL NEED TO BE MONITORED WITH MESOSCALE TRENDS.

NAM SEEMS TO BE HANGING ONTO CLOUDS LONGER ON MONDAY LENDING TO
COOLER HIGH TEMPS. AS WELL...NAM DOES NOT WARM THE UPPER LEVELS AS
QUICKLY AS THE GFS DOES. THE 12Z ECMWF IS A GOOD BALANCE BETWEEN THE
TWO AND WILL LEAN TOWARDS HIGHS IN THE LOWER 40S...MAYBE UPPER 30S.
THIS FORECAST ACCOUNTS FOR THE WARMING ALOFT AS WELL AS LINGERING
CLOUD COVER.

LOWS MONDAY NIGHT WILL BE A FIGHT BETWEEN THE WARM ADVECTION AND
RISING HEIGHTS FROM THE WEST AND A BACKDOOR SURFACE FRONT PUSHING IN
FROM THE EAST. GUIDANCE IS SHOWING THE MIDDLE GROUND TO BE RIGHT IN
THE MIDDLE OF OUR CWA WITH COLDER TEMPS TO THE EAST AND WARMER TO
THE WEST...WILL FORECAST THIS TREND BUT THIS COULD EASILY SHIFT. THE
SAME THING HAPPENS FOR HIGHS ON TUESDAY. TEND TO FEEL THAT THE UPPER
RIDGING WILL WIN OUT AND THE WARMER TEMPS IN THE LOWER 50S WILL BE
REALIZED.

THE DEEP UPPER LOW WILL CONTINUE TO ENCOMPASS MUCH OF THE EASTERN
UNITED STATES THROUGH THURSDAY WITH SHORTWAVES ROTATING AROUND THE
BASE PROVIDING THE AREA WITH PARTLY TO MOSTLY CLOUDY SKIES AND NEAR
NORMAL TEMPS ON WEDNESDAY. ANOTHER COLD FRONT WILL MOVE THROUGH THE
AREA ON THURSDAY GIVING THE AREA A CHANCE OF RAIN BUT RAINFALL
SHOULD BE LIGHT IN NATURE. RIDGING ALOFT WILL ALSO HELP TEMPS ON
THURS TO RISE INTO THE MID TO UPPER 50S. BEHIND THIS...CLOUDS WILL
SPILL OVER THE RIDGING ALOFT THROUGH THE WEEKEND. HIGHS WILL
GENERALLY REMAIN ABOUT 5 DEGREES BELOW NORMAL WITH LOWS NEAR NORMAL
FOR THIS TIME OF YEAR.

LN

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE
AT WEATHER.GOV/HUNTSVILLE.


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