424  
FXUS64 KMOB 261146 AAA  
AFDMOB  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE MOBILE AL  
646 AM CDT WED SEP 26 2018  
   
DISCUSSION
 
UPDATED FOR LATEST AVIATION DISCUSSION BELOW.  
 

 
   
AVIATION
 
 
12Z ISSUANCE...THERE IS QUITE A VARIANCE IN CEILINGS ACROSS THE  
REGION EARLY THIS MORNING. WHILE MOST LOCATIONS ARE SHOWING  
PREDOMINATE VFR CONDITIONS, THERE HAVE BEEN PERIODS OF MVFR OR  
EVEN IFR CIGS AT SEVERAL LOCATIONS. AS HEATING COMMENCES THIS  
MORNING, EXPECT VFR CONDITIONS TO PREVAIL, HOWEVER PERIODS OF  
MVFR CIGS ARE POSSIBLE CLOSER TO THE COAST, PARTICULARLY IN THE  
VICINITY OF WHERE SCATTERED SHOWERS AND THUNDERSTORMS DEVELOP.  
EXPECT STORMS TO BECOME MORE NUMEROUS THIS AFTERNOON AND PERSIST  
INTO THIS EVENING, ESPECIALLY ALONG AND WEST OF I-65. DIFFICULT TO  
REFLECT A FIRM BEGIN/END TIME FOR THUNDER GIVEN THE FAVORABLE  
CONDITIONS FOR CONVECTIVE DEVELOPMENT. BRIEF IFR CONDITIONS  
POSSIBLE IN THE STRONGER STORMS. A CHANCE FOR STORMS WILL CARRY  
INTO THE OVERNIGHT HOURS. 34/JFB  
 

 
   
PREV DISCUSSION
 
/ISSUED 504 AM CDT WED SEP 26 2018/  
 
NEAR TERM /NOW THROUGH WEDNESDAY NIGHT/...A LONGWAVE TROUGH MOVING INTO  
THE GREAT LAKES TODAY ALONG WITH ANOTHER SHORTWAVE DIVING SOUTHEAST  
OUT OF THE INTERMOUNTAIN WEST WILL SERVE TO PUSH A COLD FRONT INTO  
THE DEEP SOUTH THROUGH TONIGHT. THE BOUNDARY WILL STALL TO THE NORTH  
OF THE AREA, HOWEVER, AS STRONG RIDGING OVER THE SOUTHWEST ATLANTIC  
PERSISTS AND SHOWS NO SIGNS OF RETREATING. THIS KEEPS OUR REGION IN  
A VERY HUMID AND UNSTABLE AIRMASS. THE GOES-EAST PRECIPITABLE WATER  
PRODUCT SHOWS A LARGE AREA OF 2 PLUS INCH VALUES EXTENDING FROM THE  
BAY OF CAMPECHE INTO THE SOUTHEAST STATES. THE 00Z LIX SOUNDING  
OBSERVED A PWAT OF 2.26" WHICH IS NEAR THE DAILY RECORD. THE BEST  
RAIN CHANCES WILL EXIST ACROSS COASTAL AREAS THIS MORNING DUE TO  
WEAK ISENTROPIC LIFT AND MARINE INSTABILITY. AS WE HEAD INTO LATE  
MORNING INTO THE AFTERNOON, THE FOCUS WILL SHIFT TO NORTH AND WEST  
OF I-65 WHERE LOW LEVEL CONVERGENCE WILL BECOME ENHANCED. NUMEROUS  
TO WIDESPREAD SHOWERS AND STORMS ARE EXPECTED ACROSS THIS AREA IN  
THE AFTERNOON HOURS WHERE MLCAPES WILL CLIMB TO 1500-2500 J/KG.  
SCATTERED TO NUMEROUS STORMS ARE STILL LIKELY TO DEVELOP FURTHER  
SOUTH AND EAST THROUGH THE AFTERNOON GIVEN THE UNSTABLE AND UNCAPPED  
AIRMASS IN PLACE.  
 
SCATTERED TO NUMEROUS SHOWERS/STORMS ARE LIKELY TO PERSIST ACROSS  
THE FORECAST AREA INTO THE EVENING, ESPECIALLY ALONG AND WEST OF I-  
65. WHILE COVERAGE MAY DIMINISH OVERNIGHT, A CHANCE OF STORMS WILL  
PERSIST GIVEN PERSISTENT WEAK LOW LEVEL CONVERGENCE AND THE APPROACH  
OF A SHORTWAVE FROM THE WEST (MOVING INTO THE ARKLATEX BY SUNRISE  
FRIDAY MORNING.)  
 
LOCALIZED FLOODING WILL BE A POSSIBILITY ACROSS THE AREA TODAY AND  
TONIGHT GIVEN THE ANOMALOUSLY MOIST AIRMASS AND PERSISTENT DEEP  
LAYER SOUTHWESTERLY FLOW, ESPECIALLY THIS AFTERNOON AND EVENING WEST  
OF I-65. WILL MAINTAIN A LIMITED RISK FOR FLOODING IN OUR LOCAL  
THREAT GRAPHICS. 34/JFB  
 
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...AN UPPER RIDGE  
STRETCHING SOUTHWEST OVER THE GULF OF MEXICO FROM OFF THE EASTERN  
SEABOARD REMAINS STATIONARY THURSDAY THROUGH FRIDAY. THIS RIDGE  
CONTINUES TO DEFLECT PIECES OF SHORTWAVE ENERGY MOVING THROUGH AN  
UPPER TROUGH STRETCHING SOUTH OVER THE PLAINS. THIS ENERGY  
COMBINES WITH A VERY MOIST AIRMASS (PRECIP H20 VALUES AROUND 2.0"  
OR ABOVE) AND A STALLED SURFACE BOUNDARY STRETCHING NORTHWEST  
ALONG THE NATCHEZ TRACE TO BRING NUMEROUS SHOWERS AND  
THUNDERSTORMS INTO FRIDAY, WITH GREATEST COVERAGE BEING OVER  
NORTHWESTERN PORTIONS OF THE FORECAST AREA. WITH THE HIGH  
MOISTURE LEVELS ALLOWING FOR EFFICIENT RAIN PRODUCTION, WATER  
ISSUES WILL CONTINUE TO BE A POSSIBILITY INTO FRIDAY, ESPECIALLY  
OVER AREAS NORTHWEST OF THE I-65 CORRIDOR AND ALONG THE COAST. AT  
THIS POINT, MAINLY PONDING AND NUISANCE FLOODING IN POOR DRAINAGE  
AREAS ARE THE PRIMARY ISSUES, THOUGH WITH TRAINING CELLS POSSIBLE  
AT TIMES THURSDAY, MORE SIGNIFICANT WATER ISSUES MAY BE POSSIBLE.  
DO NOT FEEL COVERAGE OR EXTENT WILL BE GREAT ENOUGH TO WARRANT AN  
FFW, BUT WILL CONTINUE TO MONITOR. LASTLY, WITH ALL THE RAIN AND  
INCREASED CLOUD COVER, DAYTIME HIGHS AROUND SEASONAL (LOW TO MID  
80S) ARE EXPECTED. OVERNIGHT LOWS (AROUND 70 INLAND TO MID 70S  
ALONG THE COAST) A BIT ABOVE SEASONAL CONTINUE, WITH WARMING FLOW  
OFF THE GULF AND RADIATIONAL COOLING INHIBITING CLOUD COVER  
HANDING AROUND LONGER THAN USUAL.  
 
LATER FRIDAY INTO SATURDAY, A SHIFTING OF THE PLAINS UPPER TROUGH  
SHIFTS AND WEAKENS THE GULF/WESTERN ATLANTIC RIDGE TO THE  
SOUTHWEST, BECOMING CENTERED OVER FLORIDA. EVEN WITH THE  
WEAKENING, THE SHIFTING BRINGS AN INCREASE IN SUBSIDENCE TO THE  
NORTHERN GULF COAST AND THE CHANCE OF RAIN DECREASES FRIDAY NIGHT  
INTO SATURDAY. TEMPS REMAIN AT ABOVE SEASONAL LEVELS.  
 
/16  
 
LONG TERM /SATURDAY THROUGH TUESDAY/...IN THE LONG TERM, THERE  
IS MORE CONSISTENCY IN THE SYNOPTICS IN THE GUIDANCE, WITH BOTH  
GFS AND ECMWF SHIFTING THE UPPER RIDGE WEST A BIT MORE, THEN  
MOVING IT NORTH TO BECOME CENTERED OVER EASTERN PARTS OF THE  
SOUTHEAST BY SUNDAY. A SURFACE RIDGE DEVELOPS ALONG THE  
APPALACHIANS TO OFF THE MID ATLANTIC COAST, BRINGING IN DRIER AIR  
OVER THE SOUTHEAST AND EASING RAIN CHANCES THROUGH THE WEEKEND  
INTO THE COMING WEEK. THE OPERATIONAL ECMWF IS DRIEST THIS  
WEEKEND, BUT THE ECMWF ENSEMBLES ARE HINTING A MORE WETTER  
FORECAST MORE IN LINE WITH THE GFS, SO HAVE BUMPED POPS CLOSER TO  
THE GFS FORECAST. TEMPS ARE DECENTLY CONSISTENT BETWEEN EITHER  
SOLUTION, REMAINING AT ABOVE SEASONAL LEVELS, SO HAVE NOT MADE ANY  
SIGNIFICANT ADJUSTMENTS THERE.  
 
/16  
 
MARINE...A GENERAL LIGHT ONSHORE FLOW  
IS EXPECTED THROUGH THURSDAY AS A FRONT REMAINS STALLED WELL NORTH  
OF THE MARINE WATERS AND HIGH PRESSURE CONTINUES TO RIDGE INTO THE  
GULF FROM THE SOUTHWEST ATLANTIC. WINDS BECOME EVEN LIGHTER AS THE  
FRONT TRIES TO MOVE TO THE COAST BUT WEAKENS ON FRIDAY. AN EASTERLY  
FLOW BECOME PREDOMINATE OVER THE WEEKEND INTO THE EARLY NEXT WEEK AS  
HIGH PRESSURE BECOMES ESTABLISHED OVER THE EASTERN SEABOARD. THIS  
EASTERLY FLOW IS LIKELY TO BE PERIODICALLY MODERATE IN STRENGTH BY  
EARLY NEXT WEEK. SEAS WILL BE LESS THAN 2 FEET OUTSIDE OF STORMS  
THROUGH THE WEEKEND, BUT WILL LIKELY BUILD TO 2-4 FEET OVER THE OPEN  
GULF WATERS BY NEXT MONDAY/TUESDAY. 34/JFB  
 

 
   
MOB WATCHES/WARNINGS/ADVISORIES
 
 
AL...NONE.  
FL...NONE.  
MS...NONE.  
GM...NONE.  

 
 

 
 
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