866
FXUS64 KBMX 020017
AFDBMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BIRMINGHAM AL
717 PM CDT SUN AUG 1 2021
UPDATE
FOR 00Z AVIATION.
SHORT TERM
/UPDATED AT 1258 PM CDT SUN AUG 01 2021/
TODAY THROUGH MONDAY.
FEATURES OF INTEREST.
A DEEP-LAYER TROUGH EXTENDED FROM SOUTHEAST CANADA THROUGH THE
OHIO RIVER VALLEY AND DIPPED INTO THE TENNESSEE VALLEY REGION THIS
MORNING WITH SUBTLE TROUGHING OVER THE TENNESSEE VALLEY THIS
MORNING WHILE ANOTHER IMPULSE IN THE FLOW WAS ANALYZED ACROSS
PORTIONS OF IOWA AND KANSAS. THE MIDDLE AND LOWER LEVELS ARE
CHARACTERIZED BY PERSISTENT RIDGING LOCATED NEAR BERMUDA WHILE A
LESSER EXTENT OF RIDGING WAS ANALYZED TO OUR SOUTHWEST, WHICH
EXTENDED NORTHWEST INTO THE HIGH PLAINS.
TOWARD THE SURFACE, DEW POINT VALUES REMAIN THE HIGHEST ACROSS
THE WESTERN HALF OF THE AREA WITH DEW POINTS IN THE MID TO UPPER
79S WITH VALUES IN THE LOWER 70S ELSEWHERE. WEAK SURFACE PRESSURE
TROUGHING WAS ANALYZED FROM NORTH CAROLINA THAT EXTENDED SOUTHWEST
ACROSS CENTRAL GEORGIA INTO OUR SOUTHERN COUNTIES. OVERALL, A
COLD FRONT EXTENDED FROM NORTHERN TEXAS THAT STRETCHED EAST ACROSS
THE MID SOUTH REGION AND INTO SOUTHEAST TENNESSEE. A WEAK LOW WAS
ANALYZED NEAR TUPELO, MS. SURFACE HIGH PRESSURE WAS POSITIONED
OFF THE SOUTHEASTERN U.S. COASTLINE OVER THE SOUTHWEST ATLANTIC
BASIN.
HAZARD ASSESSMENT.
OBSERVED 01/12Z BMX SOUNDING ALONG WITH MODEL FORECAST SOUNDINGS
ARE IN A GOOD AGREEMENT FOR AN UPPER-END MODERATE WET MICROBURST
RISK TODAY. A TROPICAL AIRMASS NEAR THE SURFACE IS POSITIONED
BENEATH A SLUG OF DRIER AIR ALOFT. THIS CONFIGURATION WILL SUPPORT
THE RISK FOR LOCALIZED DAMAGING MICROBURST WINDS FROM THE HEAVIER
CONVECTION TODAY.
A WEAK COLD FRONT EXTENDED FROM WEST TO EAST JUST NORTH OF THE
FORECAST AREA. RARE FOR SUMMERTIME GENERALLY, THE ENVIRONMENT IS
LIGHTLY TO MODERATELY SHEARED, WHICH WILL PROMOTE STORM
ORGANIZATION. A FEW STRONG TO SEVERE STORMS WILL BE POSSIBLE WITH
THE HEAVIER ACTIVITY THAT DEVELOPS TODAY. DAMAGING WINDS WILL BE
THE PRIMARY CONCERN, CONTRIBUTED BY THE WET MICROBURST RISK
MENTIONED ABOVE.
ADDITIONALLY, WAVES OF SHOWERS AND STORMS MOVING OVER THE SAME
AREAS WILL POSE A RISK FOR LOCALIZED FLOODING DUE TO THE
TORRENTIAL DOWNPOURS WITH RAIN RATES IN EXCESS OF ONE INCH AN HOUR
EXPECTED.
NEAR TERM.
WITH SEVERAL OUTFLOW BOUNDARIES ACROSS THE AREA, UNCERTAINTY IS
HIGHER THAN TYPICAL, HOWEVER, THE MOST "EFFECTIVE" BOUNDARY
APPEARS TO BE THE ONE EXTENDING FROM NEAR TUSCALOOSA EAST TO NEAR
SYLACAUGA. EXPECT BEST CHANCES ALONG AND SOUTH OF THIS BOUNDARY
THROUGH MID AFTERNOON, FOLLOWED BY SOME INCREASED CONVECTIVE
POTENTIAL ACROSS THE AREAS NORTH OF THIS BOUNDARY. SCATTERED
SHOWERS AND STORMS LOOK TO LINGER PAST SUNSET TONIGHT INTO THE
EVENING HOURS, FOLLOWED BY THE POTENTIAL FOR SOME LINGERING
SHOWERS AND PERHAPS A THUNDERSTORM OR TWO OVERNIGHT.
TODAY.
SEVERAL BOUNDARIES WILL MOVE ACROSS THE AREA AS A WEAK COLD FRONT
APPROACHES FROM THE NORTHWEST TODAY.
EXPECT PARTLY CLOUDY SKIES WITH SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS TODAY. SOME STORMS MAY PRODUCE STRONG WINDS. HIGHS
TODAY WILL RANGE FROM THE MID 80S NORTH TO THE MID 90S SOUTH
ALONG AND SOUTH OF THE U.S. HIGHWAY 80 CORRIDOR. WINDS WILL BECOME
NORTHWEST 5-10 MPH.
TONIGHT.
EXPECT THE WEAK FRONT TO MOVE INTO OUR NORTHERN COUNTIES TONIGHT,
HELPING TO REDUCE DEW POINTS A FEW DEGREES ACROSS THE FAR NORTH.
BETTER CHANCES FOR SHOWERS AND STORMS WILL BE ACROSS THE SOUTHERN
PORTION OF THE AREA AS A DISTURBANCE MOVES EAST ALONG THE FRONT.
LOOK FOR A GRADUAL DECREASE IN SHOWERS AND THUNDERSTORMS TONIGHT
WITH THE BETTER CHANCES ACROSS THE SOUTHERN HALF OF THE FORECAST
AREA. WINDS WILL BE LIGHT OVERNIGHT WITH LOWS RANGING FROM THE
UPPER 60S FAR NORTH/NORTHEAST TO READINGS IN THE MID 70S
SOUTH/SOUTHWEST.
MONDAY.
A WEAK COLD FRONT WILL REMAIN ACROSS OUR CENTRAL COUNTIES ON
MONDAY AND WILL RESULT IN A SLIGHTLY LESS HUMID ENVIRONMENT WITH
LOWER POPS NORTH, WHILE MORE HUMID CONDITIONS WITH HIGHER CHANCES
FOR SHOWERS AND STORMS WILL EXIST ACROSS THE SOUTHERN PORTION OF
THE FORECAST AREA.
PARTLY CLOUDY SKIES ARE FORECAST MONDAY WITH SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOPING. THE BEST CHANCES WILL BE ACROSS THE
SOUTHERN HALF OF THE FORECAST AREA. HIGHS WILL RANGE FROM THE
LOWER 80S FAR NORTH TO AROUND 90 SOUTHEAST. WINDS WILL BE OUT OF
THE NORTHWEST 5-10 MPH.
05
LONG TERM
/UPDATED AT 305 PM CDT SUN AUG 01 2021/
HIGHLY AMPLIFIED TROUGH OVER THE EASTERN CONUS DISPLAYS SOME
HEIGHT FALLS TUESDAY NIGHT. THE UPPER RIDGE IN THE WESTERN
ATLANTIC BEGINS BUILDING SOUTHWESTWARD WEDNESDAY AND THURSDAY.
SIMULTANEOUSLY, THE UPPER LOW WAY UP IN NEAR HUDSON BAY EJECTS
NORTHEASTWARD AND THIS WILL LEAD TO A WEAKENING OF THE TROUGH OVER
THE EASTERN CONUS. THIS APPEARS SHORT-LIVED AS ANOTHER UPPER
TROUGH BEGINS DEVELOPING BUT DOES NOT LOOK TO BE A SEMI-PERMANENT
FEATURE. A SMALL CHANGE WAS MADE TO POPS MONDAY NIGHT INTO TUESDAY
NIGHT WITH A TAD SLOWER EXIT TREND OF POPS. OTHERWISE, THE
FORECAST TREND LOOKS GOOD WITH ONLY SMALL ADJUSTMENTS OF
TEMPERATURES HERE AND THERE. THE LOSS OF OPPRESSIVE HEAT IS MAIN
STORY.
75
PREVIOUS LONG-TERM DISCUSSION:
/UPDATED AT 257 AM CDT SUN AUG 01 2021/
MONDAY NIGHT THROUGH SATURDAY.
AN AMPLIFIED LONGWAVE TROUGH WILL REMAIN OVER THE EASTERN CONUS
THROUGH WEDNESDAY. IT WILL BE REINFORCED BY SEVERAL SHORTWAVES
ROTATING AROUND THE BASE OF THE TROUGH. THE EFFECTIVE COLD FRONT
SHOULD BE SOUTH OF THE AREA BY MONDAY EVENING, ALONG WITH THE
MORE ROBUST CONVECTION. HOWEVER, MODELS DISAGREE ON THE AMOUNT OF
POST-FRONTAL LIFT FOR SHOWERS/ISOLATED THUNDERSTORMS MONDAY NIGHT
ACROSS THE AREA. THE FRONT WILL REMAIN STALLED NEAR OR SOUTHEAST
OF OUR SOUTHEAST COUNTIES THROUGH MUCH OF THE WEEK. DRIER AIR WILL
BE FILTERING INTO THE AREA, BUT WITH PLENTIFUL MOISTURE JUST
SOUTHEAST OF THE AREA, SHORTWAVES ROTATING THROUGH THE TROUGH MAY
INDUCE WAVES OF LOW PRESSURE ALONG THE FRONT WHICH COULD ENHANCE
MOISTURE FROM THE EAST AT TIMES. DETERMINISTIC MODELS/ENSEMBLE
MEMBERS SHOW DISAGREEMENT ON RAIN CHANCES THROUGH MUCH OF THE
WEEK, SO KEPT CLOSE TO THE PREVIOUS FORECAST WITH HIGHEST CHANCES
SOUTHEAST AND VERY LIMITED CHANCES NORTHWEST. WE WILL SEE A
WELCOME RELIEF FROM THE RECENT HIGH DEWPOINTS/HEAT INDICES, AND
ALSO SEE COOLER LOW TEMPERATURES IN THE 60S AS WELL. THE TROUGH
WEAKENS BY THURSDAY, BUT OVERALL CYCLONIC FLOW REMAINS WITH
ANOTHER SHORTWAVE TROUGH MOVING THROUGH ON FRIDAY. TEMPERATURES
WILL BEGIN TO WARM BACK UP AS THE FRONT BECOMES MORE DIFFUSE, BUT
THE DEEP LAYER MOISTURE GRADIENT WILL REMAIN THROUGH THE END OF
THE PERIOD WITH CONTINUED ENSEMBLE SPREAD REGARDING ITS EXACT
POSITION.
32/DAVIS
AVIATION
00Z TAF DISCUSSION.
FRONTAL BOUNDARY MOVING S ACROSS C AL THIS EVENING CURRENTLY
BETWEEN I22 AND I20/59 W OF BHM AND JUST S OF I20 E OF BHM. TSRA
WILL BE POSSIBLE ALONG AND S OF THE BOUNDARY AS IT SAGS SWD THRU
THE TAF PERIOD. SOME MVFR CONDITIONS ALONG WITH A FEW GUSTS AT
TIMES WILL BE POSSIBLE WITH THE STORMS.
08
FIRE WEATHER
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL DEVELOP
OVER CENTRAL ALABAMA EACH AFTERNOON THROUGH MONDAY. A DECREASE IN
RAIN CHANCES CAN BE EXPECTED TUESDAY THROUGH FRIDAY, BUT STILL
SCATTERED IN NATURE. LOW LEVEL MOISTURE REMAINS VERY HIGH THROUGH
MONDAY WITH MINIMUM RH VALUES OVER 50 PERCENT. SOME DROP IS
EXPECTED THE REMAINDER OF THE WEEK BUT ONLY INTO THE 40S. AS IS
TYPICAL OF THE SUMMER PATTERN, TRANSPORT WINDS REMAIN RATHER
LIGHT.
PRELIMINARY POINT TEMPS/POPS
GADSDEN 68 85 65 87 65 / 20 20 20 20 10
ANNISTON 69 86 67 87 66 / 30 20 30 30 10
BIRMINGHAM 71 87 68 87 67 / 30 20 20 20 10
TUSCALOOSA 73 87 68 87 67 / 40 40 30 10 10
CALERA 71 86 68 86 67 / 40 30 30 20 10
AUBURN 72 87 69 85 69 / 50 70 40 50 20
MONTGOMERY 73 88 70 87 69 / 50 90 50 40 20
TROY 73 89 70 87 70 / 50 90 70 60 30
BMX WATCHES/WARNINGS/ADVISORIES/
HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR THE FOLLOWING
COUNTIES: AUTAUGA...BARBOUR...BIBB...BULLOCK...CHAMBERS...
CHILTON...CLAY...COOSA...DALLAS...ELMORE...FAYETTE...GREENE...
HALE...JEFFERSON...LAMAR...LEE...LOWNDES...MACON...MARENGO...
MONTGOMERY...PERRY...PICKENS...PIKE...RANDOLPH...RUSSELL...
SHELBY...ST. CLAIR...SUMTER...TALLADEGA...TALLAPOOSA...
TUSCALOOSA...WALKER.
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