837  
FXUS64 KBMX 181200  
AFDBMX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BIRMINGHAM AL  
600 AM CST THU JAN 18 2018  
   
UPDATE
 
 
FOR 12Z AVIATION.  
 

 
   
SHORT TERM
 
 
TODAY AND TONIGHT.  
 
THIS AM, WE CONTINUE WITH A STRONG 1039MB SURFACE HIGH PRESSURE  
PRESENT ACROSS THE GULF COAST STATES WITH ABNORMALLY COLD  
TEMPERATURES ALONG WITH THE RIDGE CENTERED OVER THE ARKLATEX.  
 
WE DID HAVE RECORD MINIMUM HIGH TEMPERATURES FOR 2 OF OUR CLIMATE  
SITES FOR YESTERDAY, JANUARY 17TH:  
 
MGM: NEW RECORD 29, REPLACES OLD RECORD OF 30 FROM 1977.  
ANB: NEW RECORD 28, REPLACES OLD RECORD OF 29 FROM 1977.  
 
THE RIDGE IS EXPECTED TO WEAKEN A LITTLE AND ELONGATE ACROSS THE  
GULF COAST STATES THROUGH TONIGHT TO NEAR 1028MB BY EARLY FRIDAY.  
WITH AMPLE SUNSHINE, WE SHOULD FINALLY SEE EVERYONE GO ABOVE  
FREEZING DURING THE DAY TODAY. WHILE TEMPERATURES WELL BELOW  
FREEZING ARE EXPECTED ONCE AGAIN TONIGHT WITH CLEAR SKIES AND NEAR  
CALM WINDS, READINGS SHOULD BE SOME 5 TO 10 DEGREES HIGHER, AND  
THUS WE ARE NOT EXPECTED TO HIT HARD FREEZE CRITERIA FOR TONIGHT.  
 
08  
   
LONG TERM
 
 
FRIDAY THROUGH WEDNESDAY.  
 
A SHORTWAVE TROUGH IN THE SOUTHERN STREAM WITH AN EMBEDDED CLOSED  
LOW WILL BE LOCATED OVER EAST TEXAS AT THE START OF THE PERIOD.  
THE GFS IS QUICKER THAN THE MODEL CONSENSUS WITH THIS FEATURE.  
USING THE CONSENSUS OF THE OTHER MODELS, THIS WILL DRIFT EASTWARD  
ACROSS THE AREA FRIDAY AND SATURDAY. IT WILL HAVE LITTLE EFFECT ON  
THE SENSIBLE WEATHER OTHER THAN SOME MID AND HIGH LEVEL CLOUDS,  
HOWEVER, AS IT WILL BE MOISTURE STARVED DUE TO LOW-LEVEL RIDGING  
OVER THE NORTHERN GULF AND THE VERY DRY AIR MASS CURRENTLY IN  
PLACE. LOW-LEVEL MOISTURE DOES BEGIN TO INCREASE FROM THE WEST ON  
SATURDAY AS THE LOW-LEVEL RIDGE MOVES EASTWARD, BUT BEHIND THE  
UPPER-LEVEL SYSTEM, SO JUST AN INCREASE IN LOWER-LEVEL CLOUDS IS  
EXPECTED IN THE WEST ON SATURDAY. AT THE SURFACE, HIGH PRESSURE  
WILL BE CENTERED OVER THE AREA ON FRIDAY, AND PUSH EAST OF THE  
AREA BY SATURDAY ALLOWING LIGHT SOUTH-SOUTHEASTERLY WINDS TO  
DEVELOP AND SOME WARM AIR ADVECTION. THE WARMING TREND WILL  
CONTINUE WITH LOW 50S FOR HIGHS ON FRIDAY, AND UPPER 50S TO AROUND  
60 ON SATURDAY.  
 
A POTENT LONGWAVE TROUGH WITH EMBEDDED CLOSED LOW WILL EJECT INTO  
THE PLAINS ON SUNDAY AND MOVE THROUGH THE MIDWEST ON MONDAY. AT  
THE SURFACE, LOW PRESSURE WILL DEVELOP IN THE LEE OF THE COLORADO  
ROCKIES, MOVE SOUTHEASTWARD TO THE PANHANDLES REGION, AND THEN  
DEEPEN AS IT MOVES INTO THE GREAT LAKES. A LINE OF SHOWERS AND  
EMBEDDED ISOLATED THUNDERSTORMS WILL DEVELOP ALONG THE TRAILING  
COLD FRONT AND MOVE EASTWARD. THE SLOWING TREND IN THE GUIDANCE  
HAS CONTINUED, AND WILL TREND TOWARDS THE MORE CONSISTENT ECMWF  
TIMING, INDICATING THE FRONTAL PASSAGE DURING THE DAY ON MONDAY.  
INCREASED POPS ON MONDAY TO CATEGORICAL FOR MUCH OF THE AREA BASED  
ON GOOD AGREEMENT AMONG EUROPEAN ENSEMBLE MEMBERS. ADDED IN SOME  
POPS IN THE EASTERN COUNTIES MONDAY EVENING GIVEN THE SLOWING  
TREND. AHEAD OF THIS ACTIVITY, A DRY AIR MASS AND WARM AIR  
ADVECTION WILL ALLOW FOR A VERY PLEASANT DAY ON SUNDAY WITH HIGHS  
IN THE LOW TO MID 60S. DESPITE STRONG WIND FIELDS, SEVERE STORMS  
CONTINUE TO LOOK VERY UNLIKELY MONDAY GIVEN AN EXPECTED LACK OF  
SURFACE-BASED INSTABILITY. THIS IS DUE TO DEW POINTS STRUGGLING  
TO REACH 60 DEGREES AND TEMPERATURES ONLY IN THE LOWER 60S WITHIN  
THE NARROW WARM SECTOR. WILL HAVE TO MONITOR IF ANY GUSTY GRADIENT  
WINDS CAN MIX DOWN FROM THE STRONG LLJ.  
 
COOLER AIR MOVES IN BEHIND THE FRONT, BUT THE ARCTIC AIR MASS WILL  
REMAIN WELL TO OUR NORTH AS IT WRAPS INTO THE OCCLUDING CYCLONE,  
AND THE FLOW ALOFT WILL BE ZONAL, RESULTING IN JUST SEASONABLE  
TEMPERATURES. AN ACTIVE PATTERN OFF OF THE PACIFIC LOOKS TO  
CONTINUE, WITH ANOTHER SHORTWAVE MOVING TOWARDS THE AREA  
WEDNESDAY. THE ECMWF INDICATES A WEAKER LESS PHASED SHORTWAVE  
WITHOUT ANY MOISTURE RETURN AHEAD OF IT. MEANWHILE THE GFS SHOWS A  
STRONGER PHASED SHORTWAVE WITH LOW PRESSURE DEVELOPING IN THE  
GULF AND THE BULK OF THE PRECIPITATION SOUTH OF THE AREA. EUROPEAN  
ENSEMBLES FAVOR A DRIER SOLUTION FOR WEDNESDAY WITH SOME SUPPORT  
FOR PRECIPITATION BY THURSDAY. UNLIKE PREVIOUS SYSTEMS THIS DOES  
NOT HAVE AN ARCTIC AIR MASS TO WORK WITH.  
 
32/DAVIS  
 

 
   
AVIATION
 
 
12Z TAF DISCUSSION.  
 
VFR TAFS FORECASTED FOR THE NEXT 24 HOURS WITH CLEAR SKIES AND A  
SURFACE HIGH PRESSURE RIDGE CURRENTLY CENTERED OVER THE ARKLATEX  
ALLOWING FOR GENERALLY NORTHWEST WINDS ACROSS CENTRAL ALABAMA.  
RIDGE IS EXPECTED TO MOVE CLOSER TO ALABAMA DURING TODAY WITH  
WINDS BECOMING LIGHT/VARIABLE TO NEAR CALM FOR TONIGHT.  
 
08  
 

 
   
FIRE WEATHER
 
 
 
A DRY AIRMASS WILL REMAIN IN PLACE WITH RH VALUES FALLING TO  
AROUND 25-35 PERCENT THIS AFTERNOON. RH VALUES WILL FALL TO  
AROUND 25 PERCENT FOR A COUPLE HOURS ON FRIDAY AFTERNOON. HOWEVER,  
WINDS WILL BE LIGHT, THUS CRITICAL FIRE WEATHER CONDITIONS ARE  
NOT EXPECTED. MOISTURE BEGINS TO GRADUALLY INCREASE ON SATURDAY.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
GADSDEN 40 18 50 27 57 / 0 0 0 0 0  
ANNISTON 41 20 50 27 57 / 0 0 0 0 0  
BIRMINGHAM 40 20 51 31 57 / 0 0 0 0 0  
TUSCALOOSA 42 20 52 31 59 / 0 0 0 0 0  
CALERA 41 21 51 30 58 / 0 0 0 0 10  
AUBURN 43 22 52 29 56 / 0 0 0 0 0  
MONTGOMERY 42 21 52 29 59 / 0 0 0 0 0  
TROY 42 21 52 30 57 / 0 0 0 0 0  
 

 
   
BMX WATCHES/WARNINGS/ADVISORIES/
 
 
HARD FREEZE WARNING UNTIL 9 AM CST THIS MORNING FOR THE  
FOLLOWING COUNTIES: AUTAUGA...BARBOUR...BIBB...BLOUNT...  
BULLOCK...CALHOUN...CHAMBERS...CHEROKEE...CHILTON...CLAY...  
CLEBURNE...COOSA...DALLAS...ELMORE...ETOWAH...FAYETTE...GREENE...  
HALE...JEFFERSON...LAMAR...LEE...LOWNDES...MACON...MARENGO...  
MARION...MONTGOMERY...PERRY...PICKENS...PIKE...RANDOLPH...  
RUSSELL...SHELBY...ST. CLAIR...SUMTER...TALLADEGA...TALLAPOOSA...  
TUSCALOOSA...WALKER...WINSTON.  
 

 
 

 
 
08/32  
 
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