558  
FXUS64 KMOB 230531 AAB  
AFDMOB  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE MOBILE AL  
1231 AM CDT THU MAR 23 2017  
   
DISCUSSION
 
UPDATED FOR LATEST AVIATION DISCUSSION BELOW.  
 

 
   
AVIATION
 
 
06Z ISSUANCE...VFR CONDITIONS OVERNIGHT WILL BECOME MVFR DURING  
THE DAY ON THURSDAY. LIGHT NORTHERLY WINDS TONIGHT SHIFT  
TO SOUTHEASTERLY AND INCREASE TO AROUND 10 TO 15 KNOTS THURSDAY  
MORNING AND AFTERNOON. /13  
 

 
   
PREV DISCUSSION
 
/ISSUED 632 PM CDT WED MAR 22 2017/  
 
DISCUSSION...UPDATED FOR LATEST AVIATION DISCUSSION BELOW.  
 
AVIATION...  
00Z ISSUANCE...ONLY FEW TO SCATTERED HIGH CLOUDS AND VFR  
CONDITIONS EXPECTED OVERNIGHT BEFORE INCREASED CLOUD COVER WITH  
VFR TO POTENTIALLY MVFR CEILINGS OVERSPREADS THE AREA FROM THE  
EAST, GENERALLY AFTER SUNRISE. LIGHT NORTHERLY WINDS TONIGHT SHIFT  
TO SOUTHEASTERLY AND INCREASE TO AROUND 10 TO 15 KNOTS THURSDAY  
MORNING AND AFTERNOON. /49  
 
PREV DISCUSSION... /ISSUED 425 PM CDT WED MAR 22 2017/  
 
NEAR TERM /NOW THROUGH THURSDAY/...WITH AN UPPER TROUGH OVER  
THE NORTHEAST SWINGING AWAY TO THE EAST AND ANOTHER MOVING ONSHORE  
OVER THE SOUTHWEST, AN UPPER RIDGE OVER THE PLAINS GETS MOVED EAST  
TO OVER THE MISSISSIPPI RIVER BY THURSDAY EVENING. SURFACE HIGH  
PRESSURE CENTERED OVER THE GREAT LAKES GETS PUSHED SOUTHEAST, TO  
OFF THE DELMARVA/CAROLINA COAST BY THURSDAY EVENING. WITH INCREASING  
SUBSIDENCE FROM THE APPROACHING UPPER RIDGE, TEMPS ABOVE SEASONAL  
EXPECTED TO CONTINUE, BUT THURSDAY NOT QUITE AS WARM AS TODAY.  
THE PROBLEMS LIES IN A WEAK FRONT GETTING PUSHED OVER EASTERN  
PORTIONS OF THE FORECAST AREA TODAY INTO TONIGHT, STALLING, THEN  
BEGINNING TO WASH OUT THURSDAY. FOR TONIGHT, THE NORTHERLY FLOW  
BRINGS IN A BIT COOLER AIR AND OVERNIGHT LOWS RANGING FROM LOW 50S  
NORTH TO AROUND 60 ALONG THE IMMEDIATE COAST. TOMORROW SEES THE  
GREATEST AFFECT FROM LINGERING CLOUDS OVER EASTERN PORTIONS OF THE  
FORECAST NO RAIN IS EXPECTED, BUT THE INCREASE CLOUDINESS INTO  
THURSDAY WILL HELP TO LIMIT DAYTIME HEATING, LEAVING AN WEST-EAST  
GRADIENT ACROSS THE FORECAST AREA FOR HIGH TEMPS, EVEN WITH THE  
APPROACHING UPPER RIDGE. HIGHS RANGING FROM MID 70S EAST TO LOW  
80S WEST. 16/SAM  
 
SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...RIDGING  
SURFACE AND ALOFT CONTINUES OVER FORECAST AREA THURSDAY NIGHT  
THROUGH FRIDAY. WITH THE SURFACE HIGH CENTERED OFF TO OUR NORTH  
AND EAST, A LOW LEVEL SOUTHEASTERLY FLOW WILL BE BRINGING  
INCREASED MOISTURE INTO THE AREA THROUGH THE PERIOD. UPPER RIDGE  
AXIS MOVES EAST OF THE FORECAST AREA BY FRIDAY AFTERNOON, WITH MID  
LEVEL FLOW ALSO BECOMING SOUTHEAST TO SOUTH BY LATE FRIDAY AND THE  
EARLY PART OF THE WEEKEND. A WELL DEFINED MID/UPPER LOW PRESSURE  
AREA DEVELOPS OVER THE PLAINS STATES BY FRIDAY AFTERNOON AND MOVES  
SLOWLY EAST-NORTHEAST TOWARD THE GREAT LAKES REGION BY THE END OF  
THE PERIOD, WITH ASSOCIATED UPPER TROF BECOMING SLIGHTLY  
NEGATIVELY TILTED AS IT MOVES EAST ACROSS OUR AREA SATURDAY  
AFTERNOON AND EVENING. MODEL DATA SHOWS SOME 500MB SHORTWAVE  
ENERGY MOVING ACROSS OUR AREA LATE SATURDAY AFTERNOON AND EVENING,  
AND WILL LIKELY HAVE A LINE OF SHOWERS OR STORMS MOVING EAST  
ACROSS THE REGION DURING THAT TIMEFRAME, AND WE HAVE MAINTAINED  
THE GOOD CHANCE TO LIKELY POPS FOR SATURDAY. THE 12Z OPERATIONAL  
GFS AND ECMWF STILL REMAIN IN GENERAL AGREEMENT THAT WE WILL HAVE  
SUFFICIENT INSTABILITY (800-900 J/KG MLCAPE) WITH SHEAR (25-35  
KNOTS OF 850 MB FLOW AND 100-200 M2/S2 STORM RELATIVE HELICITY,  
0-3KM). POTENTIAL FOR SOME STRONG TO MARGINALLY SEVERE STORMS  
OVER THE FORECAST AREA SATURDAY, BUT STILL RATHER MINIMAL LOOKING  
FOR OUR AREA AT THIS TIME. SPC DAY 4 OUTLOOK AT 15% SEVERE  
POTENTIAL FOR OUR CWA ON SATURDAY, AND WE BELIEVE IF THAT  
POTENTIAL WILL BE THERE IT WILL LIKELY BE OVER OUR WESTERN AND  
NORTHERN COUNTIES ON SATURDAY AFTERNOON. WE WILL CONTINUE TO  
MONITOR AND MENTION THE POSSIBILITY OF A FEW STRONG TO SEVERE  
STORMS IN THE HAZARDOUS WEATHER OUTLOOK. WITH CLOUD COVER,  
INCREASING PRECIPITATION CHANCES AND HIGHER DEWPOINTS, LOOK FOR  
TEMPS TO MODERATE SOMEWHAT THOUGH STILL REMAIN SLIGHTLY ABOVE  
NORMAL. HIGHS IN THE 70S EACH DAY, LOWS GENERALLY AROUND 60 EACH  
NIGHT. 12/DS  
 
LONG TERM /SUNDAY THROUGH WEDNESDAY/...BRIEF HIGH PRESSURE  
REBUILDS OVER THE REGION SUNDAY AND MONDAY, BUT ANOTHER FAST  
MOVING FRONTAL SYSTEM LIKELY TO MOVE EAST ACROSS THE AREA MONDAY  
NIGHT AND TUESDAY. SOMEWHAT UNSETTLED PATTERN THROUGH THE LONG  
TERM PERIOD WITH ISOLATED TO SCATTERED MAINLY AFTERNOON SHOWERS  
AND POSSIBLY A FEW THUNDERSTORMS. WARMER AGAIN ESPECIALLY IN THE  
DAYTIME, WITH HIGHS IN THE UPPER 70S AND LOWER 80S. NIGHTTIME  
LOWS IN THE UPPER 50S AND LOWER 60S. 12/DS  
 
MARINE...A WEAK FRONT WILL MOVE SOUTH TO NEAR THE COAST TONIGHT  
AND STALL, BRINGING NORTHEASTERLY FLOW. AS A SURFACE HIGH MOVES  
FROM THE GREAT LAKES TO OFF THE EAST COAST, FLOW OVER LOCAL COASTAL  
WATERS SHIFTS TO SOUTHEAST AND WITH A TIGHTENING GRADIENT BECOMES  
MODERATE TO STRONG. A SMALL CRAFT ADVISORY WILL BE IN EFFECT FOR  
MUCH OF THE MARINE AREA FROM 4PM THURSDAY TO 1AM SATURDAY. THE  
ONSHORE FLOW REMAINS A MODERATE TO STRONG THROUGH LATE WEEKEND  
AND INTO THE COMING WEEK. 16/SAM  
 

 
   
MOB WATCHES/WARNINGS/ADVISORIES
 
 
AL...NONE.  
FL...NONE.  
MS...NONE.  
GM...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 1 AM CDT  
SATURDAY FOR GMZ631-632-650-655-670-675.  
 

 
 

 
 
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