Area Forecast Discussion
Issued by NWS Huntsville, AL

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS64 KHUN 240950
AFDHUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
450 AM CDT FRI OCT 24 2014

.DISCUSSION...
THICK MID/HIGH-LEVEL CLOUDS AND EVEN SOME VIRGA ASSOCIATED WITH AN
APPROACHING MID-LEVEL TROUGH PERSIST ACROSS THE LOCAL AREA THIS
MORNING. SHORT TERM MODELS ARE IN GENERAL AGREEMENT IN FORECASTING
THIS TROUGH -- WHICH CURRENTLY EXTENDS FROM ONTARIO SOUTHWARD INTO
THE LOWER MISSISSIPPI VALLEY -- TO SPLIT INTO TWO PIECES LATER TODAY.
THE SOUTHERN PORTION IS FORECAST TO SHIFT SOUTHEASTWARD AND OFF THE
SOUTHEASTERN U.S. COAST BY SATURDAY EVENING...AS MODEST HEIGHT RISES
OCCUR ACROSS THE SOUTHERN PLAINS...DOWNSTREAM FROM A PACIFIC
LONGWAVE TROUGH PUSHING ONSHORE SATURDAY. AS THE TROUGH AXIS CLEARS
THE REGION THIS MORNING...EXPECT STRENGTHENING NORTHWEST FLOW AND
SUBSIDENCE ALOFT TO RESULT IN A RAPID CLEARING TREND WITH SUNNY SKIES
ALLOWING TEMPERATURES TO WARM INTO THE LOWER 70S BY AFTERNOON. A
SURFACE RIDGE DRIFTING SOUTHWARD ACROSS THE LOWER MISSISSIPPI VALLEY
WILL MAINTAIN LIGHT NNW WINDS TODAY AND NEARLY CALM CONDITIONS
TONIGHT AS THE RIDGE AXIS SETTLES OVERHEAD. THE COMBINATION OF CLEAR
SKIES AND A DECOUPLED BOUNDARY LAYER WILL PROMOTE AREAS OF FOG IN
LOCAL VALLEYS AND NEAR BODIES OF WATER AFTER MIDNIGHT. WEST-SOUTHWEST
FLOW TO THE NORTH OF THE SURFACE RIDGE WILL LEAD TO EVEN WARMER
TEMPERATURES AND A GRADUAL INCREASE IN LOW-LEVEL MOISTURE ON
SATURDAY...WITH A PASSING DISTURBANCE RESULTING IN A MINOR INCREASE
IN CLOUD COVER BY AFTERNOON/EARLY EVENING. THE DIURNAL CUMULUS FIELD
WILL DISSIPATE BY EARLY EVENING...WITH LIGHT WINDS AND RICHER
BOUNDARY LAYER MOISTURE LEADING TO A MORE WIDESPREAD FOG EVENT FOR
THE ENTIRE REGION EARLY SUNDAY MORNING. BY SUNDAY...MODELS SUGGEST
THAT THE SOUTHERN PLAINS MID-LEVEL RIDGE WILL BEGIN TO WEAKEN AND
SHIFT EASTWARD INTO THE GULF WITH SUNNY SKIES AND GRADUAL HEIGHT
RISES LEADING TO HIGHS IN THE LOWER 80S FOR ALL BUT THE HIGHER
TERRAIN LOCATIONS OF NORTHEAST ALABAMA/SOUTHERN TENNESSEE.

IN THE EXTENDED PORTION OF THE FORECAST...IT STILL APPEARS AS IF MID-
TROPOSPHERIC WINDS WILL BACK TO THE SOUTHWEST BY SUNDAY NIGHT...AS
THE CENTER OF THE SUBTROPICAL RIDGE BECOMES ESTABLISHED ACROSS THE
FLORIDA PENINSULA. THIS -- ALONG WITH STRENGTHENING SOUTHERLY RETURN
FLOW AT THE SURFACE -- WILL ALLOW FOR A GRADUAL INCREASE IN DEEP-
LAYER MOISTURE AND CLOUD COVER SUNDAY NIGHT AND MONDAY. MEANWHILE...
THE PACIFIC LONGWAVE TROUGH IS FORECAST TO ADVANCE STEADILY EASTWARD
ACROSS THE WESTERN CONUS DURING THE SECOND HALF OF THE WEEKEND...
REACHING THE CENTRAL PLAINS BY TUESDAY MORNING. STRONGER WARM/MOIST
ADVECTION DURING THE DAY ALONG WITH THE PASSAGE OF A SLIGHTLY
STRONGER MID-LEVEL WAVE MAY LEAD TO A FEW SHOWERS AND WILL RETAIN
SLIGHT CHANCE POPS. AS THE CORE OF THE LONGWAVE TROUGH BEGINS TO LIFT
NORTHEASTWARD ACROSS THE WESTERN GREAT LAKES...A DEEPENING SURFACE
LOW WILL SEND A COLD FRONT SOUTHWARD. IT NOW LOOKS AS IF THE COLD
FRONT WILL SHIFT VERY SLOWLY SOUTHWARD INTO THE REGION LATE TUESDAY
NIGHT/WEDNESDAY AS UPSTREAM HEIGHT FALLS ASSOCIATED WITH A STRONGER
SHORTWAVE MAINTAIN SOUTHWEST FLOW ALOFT OVER THE LOCAL REGION. AS THE
UPSTREAM DISTURBANCE APPROACHES...THE STALLED FRONT WILL BEGIN TO
LIFT NORTHWARD ON WEDNESDAY NIGHT -- WITH A STRONGER COLD FRONT
EXPECTED TO SWEEP THROUGH THE REGION THURSDAY AFTERNOON/EVENING. FOR
THIS REASON...WILL ONLY MAINTAIN LOW CHANCE POPS FOR SHOWERS AND
THUNDERSTORMS FROM LATE TUESDAY NIGHT-WEDNESDAY NIGHT...WITH SLIGHTLY
HIGHER POPS ON THURSDAY. THROUGHOUT THIS PERIOD...DEEP-LAYER SHEAR
WILL GENERALLY BE IN THE 30-40 KNOT RANGE WITH A VEERED LOW-LEVEL JET
OF ONLY 15-25 KNOTS. THIS COUPLED WITH CAPE VALUES OF 500-1000 J/KG
AT BEST ARGUE FOR THE THREAT OF ONLY A FEW STRONG STORMS...MAINLY
DURING THE DAY THURSDAY. A MUCH COLDER AIRMASS WILL LIKELY PENETRATE
INTO THE REGION IN THE WAKE OF THIS COLD FRONT WITH THE FIRST REAL
THREAT OF A WIDESPREAD FROST OR FREEZE COMING ON HALLOWEEN WEEKEND.

70/DD

&&

.AVIATION...
/ISSUED 1231 AM CDT FRI OCT 24 2014/
FOR 06Z TAFS...UPPER TROF AXIS WAS ALONG THE AL/MS BORDER ATTM.
MID/HIGH CLOUDS...ASSOCIATED WITH THE UPPER TROF...WILL CONTINUE
UNTIL ARND 10Z/11Z BEFORE DISSIPATING AS THE TROF MOVES EAST OF THE
TAF SITES. NO PCPN IS EXPECTED OVERNIGHT DUE TO A VERY DRY AIRMASS
OVER THE TN VALLEY. OTHERWISE VFR CONDITIONS ARE EXPECTED THRU THE
FCST PERIOD.

07

&&

.PRELIMINARY POINT TEMPS/POPS...
HUNTSVILLE    74  46  78  53 /   0   0   0   0
SHOALS        74  45  79  52 /   0   0   0   0
VINEMONT      74  46  78  53 /   0   0   0   0
FAYETTEVILLE  71  44  76  51 /   0   0   0   0
ALBERTVILLE   73  45  75  51 /   0   0   0   0
FORT PAYNE    74  44  76  51 /   0   0   0   0

&&

.HUN WATCHES/WARNINGS/ADVISORIES...

AL...NONE.

TN...NONE.

&&

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.