020  
FXUS64 KBMX 250857  
AFDBMX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BIRMINGHAM AL  
357 AM CDT SAT MAR 25 2017  
   
SHORT TERM
 
 
TAKING A PEEK AT CURRENT RADAR THIS MORNING THE PREFRONTAL MOISTENING  
BOUNDARY IS CURRENTLY WORKING INTO THE AREA THIS MORNING. THIS ARE  
MAY PROVIDE JUST A FEW ISOLATED SHOWERS TO THE NORTHWEST. NO REAL  
IMPACT FROM IT AT THIS TIME. FURTHER WEST THE MAIN LINE THAT WE WILL  
BE WATCHING TODAY IS ALREADY FAIRLY STRONG TO ISOLATED SEVERE THIS  
MORNING. INDIVIDUAL CELLS ARE MOVING NORTHEAST ALONG THE LINE WHILE  
THE LINE ITSELF IS WORKING EASTWARD AND WILL CONTINUE TO DO SO  
DURING THE MORNING. OVERALL TIMING WILL PUT THE EDGE OF THE LINE  
INTO THE FAR WESTERN COUNTIES BY 9 TO 10 AM AND THEN MOVE EASTWARD  
THROUGH THE DAY. SHOWERS AND STORMS ARE A PRETTY MUCH GIVEN FOR MOST  
OF THE AREA THROUGH TONIGHT WITH ACTIVITY GENERALLY STAYING WEST OF  
AN AUBURN TO BRUNDIDGE LINE DURING THE DAY. TEMPERATURES OF COURSE  
WILL BE A NIGHTMARE TRYING TO STAY ON TOP OF BUT THE WARMEST WILL BE  
IN THE SOUTHEAST WHERE HE RAIN HOLDS OFF. IF WE GET ANY MORE SUN  
THAN FORECASTED IN THE SOUTHEAST THEN MID 80S CAN NOT NOT BE RULED  
OUT. AS FOR TEMPERATURES IN THE WEST, LOOK FOR READINGS TO STAY IN  
THE 60S TO LOW 70S WITH THE CLOUDS AND RAIN. AS THE RAIN MOVES OUT  
TEMPERATURES MAY WARM INTO THE LOW 70S IN THE NORTHWEST, WHERE LESS  
SKY COVER IS EXPECTED. FOR AREAS IN BETWEEN THESE TWO AREAS. THE  
HIGH WILL DEPEND ON THE EXACT TIMING OF THE ONSET OF THE RAIN.  
TEMPERATURES IN THE FORECAST ARE BASED ON THE HRRR AND THEN SMOOTHED  
SO THERE COULD BE SOME VARIABILITY IN THE FORECAST VERSUS THE  
OBSERVED TEMPERATURES.  
 
SO WHAT ABOUT THE SEVERE POTENTIAL. MOST OF THE WESTERN HALF OF THE  
AREA IS UNDER A SLIGHT RISK, WHILE MOST OF THE EASTERN HALF IS UNDER  
A MARGINAL THREAT. MAIN IMPACTS WILL BE DAMAGING WINDS AND POSSIBLY  
SOME HAIL. WINDS OVERALL ARE UNI-DIRECTIONAL SO NOT MUCH IN THE WAY  
OF ROTATION TO PLAY WITH. WE WILL ALSO SEE SOME OF THE WIND FIELDS  
BEGIN TO DECREASE DURING THE AFTERNOON. LAPSE RATES ARE ALSO WEAK  
ACROSS THE AREA AS WELL. SO WHILE THERE ARE SOME NEGATIVES TO THE  
OVERALL STRENGTH OF THE STORMS, THERE ARE SOME POSITIVES AS WELL.  
JUST THE PURE DYNAMICAL FORCING OF THE LINE ITSELF, PRECIPITATION  
LOADING AND WARM SPRING TEMPERATURES DURING THE PEAK HEATING OF THE  
DAY WILL HELP INCREASE THE POTENTIAL OF MARGINALLY SEVERE WINDS WITH  
THE STRONGEST STORMS, ESPECIALLY WITH ANY LINE SEGMENT BOWING  
OBSERVED ON RADAR. MOST OF THE ACTIVITY WILL EXIT STAGE RIGHT BY 7  
TO 8 PM TONIGHT AND THE SEVERE THREAT WILL DECREASE.  
 
16  
   
LONG TERM
 
 
MOIST SOUTHWESTERLY LOW-LEVEL FLOW WILL REMAIN IN PLACE ON SUNDAY AS  
THE UPPER TROUGH TAKES A POLEWARD TURN TOWARD THE OHIO VALLEY,  
CAUSING THE SURFACE COLD FRONT TO FIZZLE TO OUR WEST. DAYTIME HEATING  
WILL AID IN THE DEVELOPMENT OF SCATTERED SHOWERS AND PERHAPS A FEW  
THUNDERSTORMS.  
 
THE NEXT SYSTEM IN THE PARADE WILL MOVE EASTWARD FROM THE PLAINS ON  
MONDAY WITH OUR NEXT CHANCE OF STORMS. SBCAPE IS STILL EXPECTED TO  
REACH 1000-2000 J/KG WITH STEEP LAPSE RATES SPREADING EASTWARD  
ACROSS MS INTO WEST AL. THE COMPACT NATURE OF THE TROUGH SHOULD  
ALLOW A MODERATE AMOUNT OF LIFT/FORCING TO OVERLAP WITH APPRECIABLE  
INSTABILITY. 0-6KM SHEAR OF 35-45 KT WILL SUPPORT STORM CLUSTERS AND  
SUPERCELLS CAPABLE OF PRODUCING HAIL POSSIBLY LARGER THAN QUARTER  
SIZE AND DAMAGING WINDS. THE TORNADO THREAT CONTINUES TO APPEAR VERY  
LOW DUE TO MARGINAL SURFACE TO 700MB SHEAR. CONVECTION COULD LINGER  
INTO TUESDAY MORNING ACROSS THE NORTH WITH A MOIST SOUTHWESTERLY  
FETCH REMAINING IN PLACE.  
 
WE SHOULD GET A BIT OF A BREAK FOR WEDNESDAY AS A 500 MB RIDGE  
AMPLIFIES OVER THE REGION AHEAD OF YET ANOTHER UPPER TROUGH. THIS  
SYSTEM WILL PROBABLY CARRY ANOTHER CHANCE FOR SEVERE STORMS ON  
THURSDAY AND COULD END UP BEING THE MOST IMPRESSIVE IN THE SERIES.  
BY THIS TIME, A LARGE WARM SECTOR SHOULD BE IN PLACE WITH THE ECMWF  
INDICATING THE POTENTIAL FOR CAPE IN THE 2000-3000 J/KG RANGE.  
 
87/GRANTHAM  
 

 
   
AVIATION
 
 
06Z TAF DISCUSSION.  
 
--VFR CLOUDINESS TONIGHT INTO SATURDAY MORNING; INCREASING THREAT  
OF THUNDERSTORMS WEST-TO-EAST THROUGH SATURDAY WITH SUB-VFR IMPACTS;  
INSTANCES OF BREEZINESS--  
 
BROKEN TO OVERCAST CLOUDINESS CONTINUES OVERNIGHT. BASED ON PROGGED  
LOW-LEVEL WINDS EITHER SIDE OF 35-KNOTS AND RH VALUES, CEILINGS ARE  
EXPECTED TO REMAIN COMFORTABLY WITHIN VFR RANGE.  
 
A WEATHER SYSTEM WILL AFFECT ALL TERMINALS SATURDAY, TRACKING WEST-  
TO-EAST ACROSS THE STATE. WE SHOULD BEGIN WITH SPOTTY/VCSH SHOWERS  
BEFORE A LINE OF THUNDERSTORMS MOVES THROUGH. SUB-VFR CONDITIONS ARE  
EXPECTED WITH THE CONVECTION (VISIBILITY AND/OR CEILINGS). GIVEN THE  
SURFACE FRONT HANGING UPSTREAM, AREAS OF LINGERING SHOWERS/STORMS  
ARE POSSIBLE BEYOND THE END OF THE TAF PERIOD AS WELL. ADDED AN  
ADDITION LINE TO SHOW TSRA TRANSITIONING TO SHRA. LATEST MODEL  
TRENDS HAVE BEEN SLOWER WITH THE EASTWARD PROGRESSION/DEVELOPMENT OF  
STORM/SHOWER ACTIVITY. ADJUSTED TIMING SLIGHTLY WHERE NEEDED.  
 
LIGHT TO MODEST BREEZES CONTINUE TONIGHT THANKS TO THE PRESSURE  
GRADIENT BETWEEN UPSTREAM LOW PRESSURE AND RIDGING OFF THE CAROLINA  
COASTLINE. GUSTY WINDS ARE EXPECTED SATURDAY, WITH GUSTS TO AROUND  
20KTS OUTSIDE OF STRONG TS.  
 
89/14  
 

 
   
FIRE WEATHER
 
 
 
LOW LEVEL MOISTURE WILL GRADUALLY INCREASES TODAY FROM WEST TO EAST  
AS A LINE OF STRONG TO POSSIBLY SEVERE STORMS MOVES ACROSS CENTRAL  
ALABAMA DURING THE DAY. RAIN CHANCES WILL CONTINUE TONIGHT AND INTO  
SUNDAY DUE TO A MOIST SOUTHWEST FLOW HOLDING OVER THE AREA. AN  
ACTIVE WEATHER PATTERN WILL CONTINUE INTO NEXT WEEK. CRITICAL FIRE  
WEATHER CONDITIONS ARE NOT EXPECTED THROUGH THE NEXT 7 DAYS.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
GADSDEN 78 59 75 58 77 / 90 90 60 20 60  
ANNISTON 78 59 76 59 78 / 80 90 50 20 60  
BIRMINGHAM 78 60 78 60 79 / 90 80 50 20 60  
TUSCALOOSA 74 60 81 60 79 / 90 70 40 10 60  
CALERA 77 59 78 61 78 / 90 80 50 10 60  
AUBURN 79 58 77 59 78 / 60 70 40 10 40  
MONTGOMERY 79 60 83 61 81 / 90 90 40 10 40  
TROY 79 60 81 61 82 / 60 80 40 10 30  
 

 
   
BMX WATCHES/WARNINGS/ADVISORIES/
 
 
NONE.  
 

 
 

 
 
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