Area Forecast Discussion
Issued by NWS Birmingham, 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 KBMX 030303
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
903 PM CST MON MAR 2 2015

.UPDATE...
EVENING UPDATE.

&&

.DISCUSSION...

A WEAK COLD FRONT HAS SLIPPED SOUTHWARD INTO NORTH ALABAMA AND WAS
LOCATED NEAR THE I-20 CORRIDOR THIS EVENING. TEMPERATURES ON THE
NORTH SIDE OF THE FRONT WERE IN THE 40S WITH 50S AND EVEN SOME
LOW 60S SOUTH OF THE FRONT. THE FRONT IS STATIONARY AND SHOULD
LIFT BACK NORTHWARD AFTER MIDNIGHT AS LOW LEVEL WIND FLOW BECOMES
SOUTHEAST. SOUTH OF THE FRONT...VISIBILITIES HAVE FALLEN QUICKLY
IN SOME AREAS WITH FOG REDUCING VISIBILITIES TO LESS THAN ONE-HALF
MILE IN SEVERAL LOCATIONS. WENT AHEAD AND ISSUED A DENSE FOG
ADVISORY FOR THE SOUTHERN HALF OF THE AREA AS THE FOG SHOULD
BECOME MORE WIDESPREAD DUE TO WARM AND VERY MOIST CONDITIONS.

VERY LITTLE RAIN ON RADAR AT THE MOMENT...BUT EXPECT SHOWERS TO
INCREASE LATER TONIGHT FOR AREAS NORTH OF I-20 AS THE SURFACE
FRONT LIFTS NORTHWARD.

58/ROSE


&&

.AVIATION...
00Z TAF DISCUSSION.

STALLED FRONTAL ZONE OVER THE AREA WITH LOTS OF MOISTURE IN PLACE.
CEILINGS STARTING OFF THIS EVENING BETWEEN 600 AND 1100 FEET AND
SEE NO REASON WHY THEY WOULD NOT LOWER THROUGH THE OVERNIGHT. IFR
EXPECTED AT ALL LOCATIONS. LIGHT SHOWERS AND DRIZZLE WILL BE
POSSIBLE THROUGHOUT THE PERIOD AS WELL. WINDS VERY LIGHT AT 5 KTS
OR LESS.

88


&&

.PREV DISCUSSION...
/ISSUED 547 PM CST MON MAR 2 2015/

A FRONT IS CURRENTLY STALLED ACROSS THE FORECAST AREA WITH
TEMPERATURES VARYING SOME 20 TO 25 DEGREES ACROSS CENTRAL ALABAMA
FROM LOW 40S ACROSS THE NORTHWEST TO LOW 70S ACROSS THE SOUTHEAST.
CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATES
RATHER ZONAL FLOW ACROSS THE SOUTHEAST. THIS UPPER LEVEL FLOW IS
PARALLEL TO THE FRONTAL BOUNDARY AND EXPECT THE FRONT WILL REMAIN
STATIONARY THROUGHOUT MUCH OF THE OVERNIGHT HOURS BEFORE SURFACE
WINDS BECOME MORE SOUTHWESTERLY IN RESPONSE TO A LEE LOW DEVELOPING
AND THE SURFACE HIGH MOVING TO THE NORTHEAST. UPPER LEVEL WINDS WILL
BECOME FROM THE WEST SOUTHWESTERLY LATER TONIGHT INTO TOMORROW
MORNING AS THE UPPER LEVEL TROUGH CURRENTLY LOCATED ACROSS SOUTHERN
CALIFORNIA BEGINS TO AMPLIFY AND EJECT TO THE EAST. WITH THE SURFACE
BOUNDARY REMAINING MOSTLY UNCHANGED THROUGHOUT THE OVERNIGHT
HOURS...FOG WILL BE POSSIBLE ONCE AGAIN OVERNIGHT AND MAY NEED TO
ISSUE A DENSE FOG ADVISORY LATER ON THIS EVENING. CONFIDENCE IS NOT
HIGH ENOUGH AT THE CURRENT TIME IN WIDESPREAD VISIBILITY BELOW 1/4
MILE. FOR NOW...HAVE MENTIONED THE POSSIBILITY OF FOG IN THE HWO.
SCATTERED TO NUMEROUS LIGHT SHOWERS WILL CONTINUE DURING THE
OVERNIGHT HOURS AS THE LINGERING BOUNDARY WILL PROVIDE LIFT.

ON TUESDAY...THE FORECAST AREA SHOULD BE WELL INTO THE WARM SECTOR
WITH SOUTHERLY WINDS IN THE LOW LEVELS. UPPER LEVEL HEIGHTS WILL
INCREASE IN RESPONSE TO THE DEEPENING LOW FURTHER TO THE WEST. HIGH
TEMPERATURES WILL SOAR TUESDAY AFTERNOON INTO THE 70S ACROSS THE
FORECAST AREA WITH STRONG SOUTHERLY WINDS ADVECTING IN WARM AND
MOIST AIR. MODEL SOUNDINGS INDICATE JUST ENOUGH INSTABILITY FOR A
FEW THUNDERSTORMS TO DEVELOP DURING THE AFTERNOON BUT THE LIFT ALONG
THE FRONT WILL BE WELL TO THE NORTH BY THE AFTERNOON...AND HAVE GONE
WITH LOWER POPS DURING THIS TIMEFRAME.

TUESDAY AND BEYOND IS WHERE THE FORECAST GET VERY INTERESTING ONCE
AGAIN EXPECT CENTRAL ALABAMA WILL GO FROM TEMPERATURES IN THE 70S
WITH A FEW THUNDERSTORMS TUESDAY AND WEDNESDAY AFTERNOONS TO A
POTENTIAL WINTER STORM LATE WEDNESDAY NIGHT INTO THURSDAY MORNING.
THE MAIN DIFFERENCE IN THE MODEL SOLUTIONS FOR THE MID-WEEK SYSTEM
IS TIMING. THE MODELS ARE BEGINNING TO CONVERGE ON A BETTER
SOLUTION FOR THE ARRIVAL OF THE ARCTIC AIR. THE GFS HAS SLOWED DOWN
SOME BUT IS STILL THE FASTEST MODEL. HAVE GONE WITH MORE OF A
CONSENSUS OF THE ECMWF...GEM AND NAM TIMING. MODEL SOUNDINGS AGAIN
SHOW LOW INSTABILITY VALUES ON WEDNESDAY...GENERALLY UNDER 250 J/KG
WITH WINDS BECOMING SOUTHWESTERLY AHEAD OF THE FRONT.
THEREFORE...THE SHEAR AND INSTABILITY IS LIMITED ACROSS THE FORECAST
AREA. STILL THINK A STRONG STORM OR TWO WILL BE POSSIBLE BUT NOT
EXPECTING ANYTHING SEVERE.

A BIG CHANGE IN SEASONS WILL OCCUR AS THE ARCTIC FRONT BLASTS THROUGH
THE AREA LATE WEDNESDAY INTO EARLY THURSDAY. STILL THINK THAT
TEMPERATURES BELOW FREEZING DO NOT ARRIVE INTO NORTHWESTERN PORTIONS
OF CENTRAL ALABAMA UNTIL AROUND MIDNIGHT. AS THE NORTHERN STREAM
PHASES WITH THE SOUTHERN STREAM AN INCREDIBLE UPPER LEVEL JET OF
OVER 180KTS DEVELOPS ACROSS THE OHIO RIVER VALLEY INTO THE NORTHEAST.
THIS WILL PUT CENTRAL ALABAMA IN THE RIGHT ENTRANCE REGION OF AN
INTENSE JET. SYNOPTIC LIFT WILL BE PLENTIFUL BEHIND THE FRONT AND
MOST OF THE MODEL SOLUTIONS SHOW THIS AS WELL. THE REAL CHALLENGE
WILL BE WATCHING THE FREEZING LINE MOVE ACROSS THE AREA LATE
WEDNESDAY INTO EARLY THURSDAY. FOR NOW EXPECT THIS LINE WILL MAKE
IT AROUND THE I-59 CORRIDOR AROUND 12Z THURSDAY. CONFIDENCE IS
HIGHEST IN RECEIVING SIGNIFICANT ICE ACCUMULATIONS OVER THE
NORTHWESTERN FIVE COUNTIES (MARION...LAMAR...WINSTON...FAYETTE AND
WALKER). CLOSER TO THE I-59 CORRIDOR CONFIDENCE DECREASES SOME BUT
EXPECT LIGHT FREEZING RAIN ACCUMULATIONS WILL BE POSSIBLE DOWN TO
DEMOPOLIS TO CALERA TO ANNISTON LINE. FURTHER SOUTH OF THIS LINE
CONFIDENCE IS LOW THAT ANY FREEZING RAIN ACCUMULATION WILL OCCUR.
FOR NOW...HAVE HELD OFF ON ISSUING A WATCH WITH THE EVENT STILL 3
DAYS AWAY AND STILL HIGH UNCERTAINTY WITH THIS EVENT.

ALL THE MODELS SHOW VERY IMPRESSIVE COLD AIR ADVECTION BEHIND THE
SYSTEM WITH A FEW LOCATIONS NORTH OF I-20 POSSIBILITY STAYING BELOW
FREEZING ALL DAY THURSDAY. IF THERE IS SNOW OR ICE ON THE GROUND
FRIDAY MORNING EXPECT TEMPERATURES IN THE SINGLE DIGITS WILL BE
POSSIBLE NORTH OF THE I-20 CORRIDOR. EXPECT SOME LOCATIONS MAY NOT
MAKE IT ABOVE FREEZING UNTIL FRIDAY AFTERNOON AS TEMPERATURES BEGIN
TO MODERATE LATE IN THE WEEK AND INTO THE WEEKEND. HAVE CONTINUED
LOW POPS OVER THE WEEKEND WITH THE ECMWF SHOWING A GULF LOW
DEVELOPING. THE GFS SHOWS THE LOW SUPPRESSED FOR NOW AND WILL
CONTINUE WITH LOW POPS MENTIONED.

05/MA

&&

.PRELIMINARY POINT TEMPS/POPS...
GADSDEN     48  68  61  67  31 /  60  60  50  60 100
ANNISTON    51  69  62  69  35 /  60  60  40  50 100
BIRMINGHAM  48  73  63  69  30 /  60  50  40  60 100
TUSCALOOSA  48  75  64  71  31 /  60  40  40  60 100
CALERA      53  74  63  70  33 /  50  40  40  50 100
AUBURN      57  74  61  72  49 /  40  30  20  40  90
MONTGOMERY  57  76  63  74  44 /  40  20  20  40  80
TROY        58  76  62  75  51 /  40  20  20  30  80

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 9 AM CST TUESDAY FOR THE FOLLOWING
COUNTIES: AUTAUGA...BARBOUR...BIBB...BULLOCK...CHAMBERS...
CHILTON...CLAY...COOSA...DALLAS...ELMORE...GREENE...HALE...LEE...
LOWNDES...MACON...MARENGO...MONTGOMERY...PERRY...PIKE...
RANDOLPH...RUSSELL...SUMTER...TALLAPOOSA.

&&

$$






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