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 231136
AFDBMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
636 AM CDT SAT AUG 23 2014

.UPDATE...
FOR 12Z AVIATION.

&&

.DISCUSSION...

LOOKS LIKE THE FORECAST WILL BE A BIT MORE CHALLENGING TODAY THAN
WHAT WAS BEING ADVERTISED BY GUIDANCE OVER THE PAST TWO DAYS.
LET`S START WITH THE HEAT. STILL THINKING THAT MOST OF CENTRAL
ALABAMA WILL BE VERY HOT THIS AFTERNOON...BUT A BIT COOLER THAN
PREVIOUSLY ANTICIPATED. UPPER LEVEL HEIGHTS ARE ACTUALLY DROPPING
TODAY AS THE UPPER RIDGE STARTS TO RETROGRADE AND LOSE A BIT OF
ITS PUNCH. LOOKING AT 1000-850MB THICKNESSES...THEY ARE LOWER
TODAY ESPECIALLY ACROSS EASTERN AND NORTHEASTERN COUNTIES THIS
AFTERNOON THAN YESTERDAY. LOOKING BACK AT TEMPERATURES
YESTERDAY...MOST LOCATIONS EAST OF INTERSTATE 65 OBSERVED BELOW
HEAT ADVISORY CRITERIA BY AT LEAST 2-3 DEGREES. IF LOW-LEVEL
THICKNESSES HAD BEEN ADVERTISED JUST AS HIGH AS YESTERDAY WE WOULD
HAVE KEPT THE ADVISORY...BUT IT JUST DOESN`T SEEM WARRANTED BASED
ON A CRITERIA STANDPOINT TO DO SO FOR SEVERAL OF OUR EASTERN AND
NORTHEAST COUNTIES. NOW...THAT`S NOT SAYING IT WON`T STILL BE VERY
HOT AND OPPRESSIVE OUT THERE SO FOLKS SHOULD STILL MAKE SURE THEY
TAKE THE PROPER PRECAUTIONS TO PREVENT HEAT RELATED ILLNESSES THIS
AFTERNOON. THE HEAT ADVISORY WILL CONTINUE FOR THE REST OF CENTRAL
ALABAMA THROUGH 9PM TONIGHT.

NOW THE NEXT CHALLENGE...WHICH WILL BE CONVECTIVE DEVELOPMENT THIS
AFTERNOON. SINCE THE UPPER RIDGE HAS BEGUN TO RETROGRADE...WE`RE
ALREADY SEEING IMPULSES TRAVERSING SOUTHWARD ON THE PERIPHERY OF
THE RIDGE. SHOWERS AND STORMS ARE ALREADY OUT THERE ACROSS
NORTHERN TENNESSEE ASSOCIATED WITH AN UPPER LEVEL IMPULSE THAT
MOVED SOUTHEASTWARD FROM ILLINOIS AND INDIANA YESTERDAY. LOOKING
AT THE HIGH-RES WRF ARW AND HRRR MODELS THIS MORNING...THEY BOTH
HAVE A LOW-LEVEL MESOSCALE BOUNDARY MOVING SOUTHWARD INTO NORTHERN
ALABAMA BY THIS AFTERNOON. THIS IS THE SAME BOUNDARY THE CURRENT
STORMS ARE BEING TRIGGERED FROM JUST NORTH OF NASHVILLE. SINCE
WE`LL HAVE A BIT OF UPPER LEVEL FORCING DUE TO THE WEAK
DISTURBANCE AND THE MESOSCALE BOUNDARY...AT LEAST SCATTERED
CONVECTION IS EXPECTED TO DEVELOP LATE THIS AFTERNOON AND LASTING
THROUGH THE EARLY EVENING HOURS FOR OUR NORTHERN AND EASTERN
COUNTIES. FORECAST SOUNDINGS ARE ADVERTISING A WEAKLY CAPPED
ENVIRONMENT THAT SHOULD BE ERODED WITH DAYTIME HEATING. PLENTY OF
LOW-LEVEL MOISTURE WILL BE AVAILABLE...SO IF A TRIGGERING
MECHANISM (MESOSCALE BOUNDARY) LIFTS THE PARCELS PAST THE LFC...AT
LEAST SCATTERED CONVECTION SHOULD BE ACHIEVED. ISOLATED STORMS ARE
EXPECTED ELSEWHERE FOR THE SOUTHEAST COUNTIES...WHILE NO RAIN
CHANCES ARE EXPECTED SOUTHWEST AT THIS TIME.

LOOKING FORWARD INTO SUNDAY...THIS WILL ALSO BE A CHALLENGING DAY
WITH THE WEATHER PATTERN CHANGING QUICKLY ACROSS THE SOUTHEAST.
EASTERLY FLOW AT THE SURFACE WILL QUICKLY MOVE INTO OUR EASTERN
COUNTIES BY SUNDAY AFTERNOON. THE EASTERLY FLOW ALONG WITH UPPER
LEVEL IMPULSES MOVING SOUTHWARD AROUND THE UPPER RIDGE WILL HELP
TO PRODUCE SCATTERED TO NUMEROUS SHOWERS AND STORMS...AND HAVE
INTRODUCED LIKELY POPS ACROSS OUR EASTERN COUNTIES GENERALLY EAST
OF INTERSTATE 65. WITH THE CLOUD COVER ASSOCIATED WITH THE
CONVECTION AND UPPER DISTURBANCES MOVING IN...WE MIGHT NOT BE ABLE
TO ACHIEVE HEAT ADVISORY CRITERIA FOR MORE OF OUR COUNTIES. FOR
NOW...HAVE ONLY REMOVED WINSTON AND WALKER FROM THE HEAT ADVISORY
ON SUNDAY. HOWEVER...WITH GUIDANCE COMING IN WITH AT LEAST BROKEN
CLOUD COVER FOR MUCH OF CENTRAL ALABAMA ON SUNDAY WE MAY HAVE TO
REMOVE MORE COUNTIES FROM THE ADVISORY OVER THE NEXT FEW FORECAST
PACKAGES. SHOWERS AND STORMS SHOULD GENERALLY MOVE FROM EAST TO
WEST ACROSS THE STATE ON SUNDAY THROUGH THE EARLY MORNING HOURS ON
MONDAY.

DRY AIR WILL EVENTUALLY ADVECT WESTWARD INTO THE STATE THROUGH THE
DAY ON MONDAY...WITH THE BEST RAINFALL CHANCES WEST OF I-65 DURING
THE AFTERNOON. IF CURRENT GUIDANCE TRENDS HOLD TRUE...TUESDAY AND
WEDNESDAY OF NEXT WEEK ARE LOOKING VERY PLEASANT IF THE POSSIBLE
TROPICAL SYSTEM IN THE CARIBBEAN DOES IN FACT DEVELOP AND RE-CURVE
EAST OF THE CAROLINAS. THAT WOULD PLACE CENTRAL ALABAMA IN THE
"WEDGE" WITH COOLER AND DRIER AIR MOVING DOWN THE EASTERN SIDE OF
THE APPALACHIANS. THE FORECAST IS CURRENTLY GOING WITH DRIER AND
COOLER CONDITIONS BASED ON GUIDANCE TRENDS THE PAST COUPLE OF
DAYS. THE REMAINDER OF THE FORECAST PERIOD REMAINS NEAR CLIMO FOR
TEMPERATURES AND POPS...WITH UPPER RIDGING EXPECTED TO REMAIN THE
DOMINANT FEATURE ACROSS THE EASTERN CONUS.

56/GDG

&&

.AVIATION...
12Z TAF DISCUSSION.

CONDITIONS SHOULD REMAIN FAIRLY TRANQUIL THROUGH THE FIRST 6 HOURS
OF THE TAF PERIOD. STARTING AT 21Z...INCLUDED VCSH FOR KBHM AND
KANB FOR POSSIBLE ISOLATED SHOWERS...BUT A THUNDERSTORM CANNOT BE
RULED OUT. OTHERWISE VFR CONDITIONS ARE EXPECTED FOR ALL SITES
WITH GENERALLY LIGHT NORTHWEST WINDS.

87/GRANTHAM

&&

.BMX WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR THE FOLLOWING
COUNTIES: BARBOUR...BULLOCK...ELMORE...JEFFERSON...MACON...
PIKE...RUSSELL...SHELBY...WALKER...WINSTON.

HEAT ADVISORY UNTIL 9 PM CDT SUNDAY FOR THE FOLLOWING COUNTIES:
AUTAUGA...BIBB...CHILTON...DALLAS...FAYETTE...GREENE...HALE...
LAMAR...LOWNDES...MARENGO...MARION...MONTGOMERY...PERRY...
PICKENS...SUMTER...TUSCALOOSA.

&&

$$

87/56





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