Area Forecast Discussion
Issued by NWS Huntsville, AL

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000
FXUS64 KHUN 290301 AAB
AFDHUN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
901 PM CST WED JAN 28 2015

.UPDATE...
EVENING UPDATE.

&&

.DISCUSSION...
HIGH CLOUDS ARE NOW OVERSPREADING THE WESTERN PART OF THE FORECAST
AREA AS OF 03Z. THIS WILL LIMIT TEMPERATURES FROM FALLING AS LOW AS
THEY HAVE BEEN IN PREVIOUS NIGHTS. IN THE EASTERN AREAS...TEMPS STILL
HAVE ANOTHER HOUR OR TWO TO GET COLDER. HAVE THEREFORE UPDATED
OVERNIGHT LOWS...WESTERN AREAS HAD TO GO UP A DEG OR TWO AND EASTERN
WERE GENERALLY STEADY WITH FORT PAYNE EXPECTED TO GET AROUND FREEZING
TONIGHT. OTHERWISE...NO CHANGES WERE MADE.

LN

&&

.AVIATION...
/ISSUED 525 PM CST WED JAN 28 2015/
FOR 00Z TAFS...VFR CONDITIONS AND LIGHT WINDS WILL PREVAIL OVERNIGHT.
WITH A COLD FRONT APPROACHING ON THURSDAY...CIGS WILL LOWER AND
EVENTUALLY REACH 2-3KFT BY 21Z THURSDAY. THE TIMING OF THE LOWER OF
THE CIGS COULD BE OFF +- AN HOUR OR TWO IN EITHER DIRECTION. THERE IS
A CHANCE OF RAIN AS WELL THURSDAY EVENING BUT TOO LOW CONFIDENCE AT
THIS TIME TO INCLUDE IN THE TAFS.

LN

&&

.PREV DISCUSSION...
/ISSUED 326 PM CST WED JAN 28 2015/
DRY WEATHER AND SEASONABLY COOL CONDITIONS PREVAILED ACROSS THE
GREATER TENNESSEE VALLEY THIS AFTERNOON...THANKS TO SURFACE HIGH
PRESSURE OVER THE OHIO VALLEY/WESTERN APPALACHIANS. THIS HIGH
SLIDING TO THE EAST HAS RESULTED IN LIGHT/VARIABLE WINDS THIS
MORNING...WHICH WERE SLOWLY BECOMING LIGHT FROM THE SE. MID
AFTERNOON HIGH TEMPERATURES HAVE RISEN INTO THE LOW/MID 50S.

ALOFT...A NW FLOW CONTINUED FROM THE NE PLAINS TO THE SE COAST AS
WEAK UPPER RIDGING MOVES ACROSS THE DEEP SOUTH. THE UPPER LEVEL
PATTERN WAS HOWEVER BECOMING A BIT MORE OF A SPLIT FLOW AFFAIR...
AS A SURGE OF SUBTROPICAL MOISTURE ORIGINATING FROM AROUND 10N120W
HEADS TOWARDS THE DESERT SW.

AN UPPER LEVEL SYSTEM (OR CLIPPER) MOVING ACROSS SASKATCHEWAN IN A
STILL BUSY NORTHERN STREAM WILL MOVE ESE TOWARDS THE GREAT LAKES
OVER THE NEXT DAY OR SO. THIS SYSTEM...ALONG WITH A UPPER TROUGH
NOW PROGRESSING EASTWARD ACROSS THE EASTERN PLAINS WILL BRING
INCREASING CLOUDS AND A CHANCE OF RAIN TO THE AREA BEGINNING
TOMORROW. MODEL OUTPUT EVEN IN THIS SHORT RANGE WAS NOT IN GOOD
AGREEMENT...WITH THE NAM/SREF THE DRIEST...THE GFS/GEM A TAD
WETTER...AND ECMWF THE WETTEST. GIVEN A DRY TREND FROM THE NAM AND
ITS ENSEMBLE...HAVE DELAYED THE START FOR "CHANCE" POPS UNTIL THU
AFTERNOON. RAIN CHANCES SHOULD WIND DOWN FROM WEST TO EAST THU
EVENING AS THE SYSTEM EXITS TO THE EAST. RAIN AMOUNTS WITH THIS
SYSTEM SHOULD REMAIN ON THE LIGHT SIDE...ONLY UP TO A FEW HUNDRETHS
OF AN INCH MAINLY NEAR AND NORTH OF THE AL/TN STATE BORDER. GIVEN
THE RAIN SHOULD END BEFORE POST SYSTEM COLD AIR ARRIVES...HAVE
HELD ONTO ALL LIQUID PRECIP THU EVENING.

AN UPPER SYSTEM NOW A FEW HUNDRED MILES WEST OF THE BAJA WAS
MOVING EASTWARD TO THE SUBTROPICAL MOISTURE SURGE. MODEL GUIDANCE
THE PAST FEW DAYS CONTINUED TO INDICATE A SOUTHERN STREAM WEATHER
MAKER IS SET TO FORM...AND BRING WIDESPREAD PRECIP ACROSS THE
SOUTHERN ROCKIES AND ADJACENT REGIONS. IT WILL BRING A GOOD CHANCE
OF RAIN TO THIS AREA BY EARLY NEXT WEEK...AS IT MOVES EASTWARD.
THE MODELS (GFS/ECMWF) WERE IN GENERALLY GOOD AGREEMENT CONCERNING
WHEN RAIN SHOULD BEGIN...WITH THE CANADIAN NOT BRINGING THE BULK OF
ITS PRECIP TILL AFTER SUNSET SUN EVENING. IN ANY CASE...SOUNDINGS
PROFILES LOOK TOO STABLE FOR THUNDER FOR OUR AREA. AS THE MAIN
SYNOPTIC LOW PASSES BY TO OUR NORTH...A COLD FRONT SHOULD MOVE
ACROSS THE AREA SUN EVENING...WITH RAIN GRADUALLY ENDING FROM WEST
TO EAST. GIVEN COLDER AIR MOVING IN BEHIND THIS SYSTEM...HAVE
CONTINUED A RAIN/SNOW MIX FOR LATE SUN NIGHT TO A FEW HOURS AFTER
DAYBREAK MON. WITH THE SHOWER ACTIVITY AND CLOUDS...HIGHS DURING
THE WEEKEND WILL REMAIN A TAD COOLER THAN NORMAL...ONLY RISING TO
AROUND 50 SUN. WITH DECENT COLD AIR ADVECTION...ONLY AROUND 40 TO
START A NEW WORK WEEK OR MON.

BOTH THE GFS/ECMWF DEPICT ANOTHER SYSTEM AFFECTING THE FORECAST
AREA NEXT MID WEEK. THE GFS THIS GO AROUND WAS WETTER THAN THE
EC. THE LATTER HAS POSITIONED ITS DEVELOPING LOW FURTHER TO THE
NORTH THAN THE EC. HAVE ADDED A SLIGHT CHANCE OF RAIN FOR THE
MIDWEEK. GIVEN THE COLDER AIR IN PLACE...STARTED THE PRECIP AS A
RAIN/SNOW MIX...BECOMING ALL RAIN SHORTLY AFTER DAYBREAK WED.

RSB

&&

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

$$

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



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