FXUS64 KMOB 100317 AFDMOB AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MOBILE AL 1015 PM CDT SAT MAY 9 2009 .UPDATE...UPDATED ZONES AND GRIDS TO REFLECT SMALL CLUSTER OF THUNDERSTORMS APPROACHING FAR NWRN CORNER OF FCST AREA...WHERE WE INTRODUCED CHANCE POPS FOR THE REMAINDER OF THE EVENING THEN EXPECT RAIN CHANCES TO BECOME MORE ISOLATED OVER INTERIOR ZONES AFTER MIDNIGHT. THE STORMS MENTIONED ARE NOW BEGINNING TO WEAKEN WITH THE LOSS OF DAYTIME HEATING...BUT WILL LINGER LONG ENOUGH TO AFFECT PARTS OF THE NWRN FCST AREA THROUGH AROUND MIDNIGHT...PRIMARILY CHOCTAW COUNTY. APPEARS ANY SVR THREAT WILL BE VERY MARGINAL...BUT THE STORMS COULD BE BRIEFLY STRONG. MAIN THREAT OVER THE NEXT COUPLE OF HOURS LOOKS TO BE A PERIOD OF HEAVY RAINFALL OVER PARTS OF CHOCTAW COUNTY...ESPECIALLY NORTHERN SECTIONS. RADAR ESTIMATES INDICATED THAT 1 TO 2 INCHES OF RAIN PER HOUR HAS BEEN OCCURRING WITH THESE STORMS...AND RAINFALL AT THIS RATE COULD PRODUCE SOME MINOR FLOODING AND RUNOFF IN POOR DRAINAGE AREAS. WE WILL CONTINUE TO MONITOR. 12/DS AS FAR AS THE MARINE FCST UPDATE IS CONCERNED...NO MAJOR CHANGES FOR TONIGHT. OTHERWISE...A RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE NORTHERN GULF COASTAL WATERS THROUGH SUNDAY NIGHT. A WEAK FRONT WILL STALL ALONG THE COAST SUNDAY NIGHT BRINGING LIGHT WEST WINDS BY MONDAY MORNING. WINDS BECOME NORTHERLY DURING THE DAY MONDAY AS HIGH PRESSURE SAGS SOUTH. AN ONSHORE FLOW RETURNS BY WEDNESDAY AS A LOW PRESSURE SYSTEM ADVANCES ACROSS THE PLAINS. 08/JW .00Z AVIATION DISCUSSION...SHORT LIVED MVFR CEILINGS A POSSIBILITY LATE TONIGHT AND EARLY TOMORROW MORNING NEAR THE COAST. PATCHY FOG DEVELOPMENT SHOULD REMAIN CONFINED TO OUR MORE INLAND LOCATIONS AND BURN OFF QUICKLY FOLLOWING SUNRISE. A WEAK FRONTAL BOUNDARY WILL SAG SOUTHWARD ACROSS SOUTHERN ALABAMA TOMORROW AFTERNOON TRIGGERING ISOLATED THUNDERSTORMS AND SHOWERS PRIMARILY NORTH OF INTERSTATE 10. 08/JW ** PREVIOUS DISCUSSION ** .SHORT TERM...FOR TONIGHT THROUGH TUESDAY NIGHT...THE FRONTAL BOUNDARY...SEEN IN THE LATEST SURFACE ANALYSIS STRETCHED FROM SOUTHERN ARKANSAS TO EASTERN TENNESSEE...MOVED GRADUALLY SOUTHWARD THROUGH TONIGHT AND INTO THE NORTHERN PORTION OF THE FORECAST AREA. WILL STAY WITH SMALL POPS OVER THE NORTHERN PORTION OF THE AREA FOR TONIGHT WITH PATCHY FOG DEVELOPING AFTER MIDNIGHT...DENSE NEAR CEW/GZH/79J. AS A SURFACE HIGH ADVANCES EASTWARD ACROSS THE PLAINS...THE FRONT CONTINUES TO MOVE SLOWLY SOUTHWARD AND EVENTUALLY MOVES TO ALONG THE GULF COAST LATE MONDAY AFTERNOON THEN INTO THE NEAR SHORE MARINE WATERS MONDAY NIGHT. SPC HAS A SLIGHT RISK OUT FOR THE NORTHERNMOST COUNTIES OVERNIGHT...BUT AS NOTED IN THE SWODY1 DISCUSSION CONFIDENCE IS LOW WITH THIS RISK AREA AND AM NOT ANTICIPATED SEVERE STORM DEVELOPMENT OVERNIGHT. SPC HAS A SLIGHT RISK FOR ALL BUT THE COASTAL AREAS ON SUNDAY THEN MORE OVER THE SOUTHERN HALF OF THE AREA ON MONDAY AS THE FRONT CONTINUES TO MOVE SOUTHWARD. THIS IS MAINLY DUE TO INCREASING INSTABILITY DUE TO DAYTIME HEATING ON SUNDAY AND A MARGINAL AMOUNT OF DRY AIR PRESENT ABOVE 750 MB WHICH RESULT IN WET BULB ZERO VALUES NEAR 11 KFT...BUT 0-1 KM HELICITIES WILL REMAIN FAIRLY TAME AS GENERALLY LESS THAN 70 M2/S2. HAVE HELD OFF ON MENTIONING SEVERE IN THE ZONES FOR SUNDAY GIVEN THE RELATIVELY LOW CHANCE RANGE POPS AND LIKEWISE HELD OFF FOR MONDAY AS MODEL SOUNDINGS CONTINUE TO SHOW MOISTENING WITH WET BULB ZERO VALUES RISING ABOVE 12 KFT. CHANCE POPS CONTINUE FOR TUESDAY AS THE FRONT RETURNS NORTHWARD AS A SYSTEM ADVANCES ACROSS THE PLAINS. TEMPERATURES WILL ABOVE SEASONABLE LEVELS ON SUNDAY THEN RETURN TO MORE SEASONABLE LEVELS FOR MONDAY AND TUESDAY. /29 && .LONG TERM...WEDNESDAY THROUGH SATURDAY...THE PLAINS SYSTEM GETS CUT OFF OVER TEXAS ON WEDNESDAY WHILE A MUCH STRONGER CANADIAN SYSTEM BRINGS A TRAILING FRONT INTO THE SOUTHEAST STATES ON THURSDAY. THE TRAILING FRONT STALLS OVER THE FORECAST AREA THURSDAY NIGHT INTO FRIDAY. THE FRONT RETURNS NORTHWARD AS A WEAK WARM FRONT ON SATURDAY AS ANOTHER SYSTEM MARCHES ACROSS THE PLAINS. STAYED WITH LOW END CHANCE POPS FOR WEDNESDAY AND THURSDAY THEN SMALL POPS FOR FRIDAY AS SATURDAY. TEMPERATURES WILL GENERALLY BE ABOVE SEASONABLE LEVELS. /29 && .MARINE...LIGHT SOUTHERLY FLOW WILL CONTINUE INTO THE COMING WEEK AS A WEAK SURFACE BOUNDARY GETS PUSHED TOWARDS THE NORTHERN GULF COAST. GUIDANCE HAS THIS BOUNDARY PUSHING OFFSHORE MONDAY NIGHT INTO TUESDAY MORNING...BUT GUIDANCE IS ADVERTISING SOUTHERLY FLOW BECOMING RE-ESTABLISHED BY THE END OF THE DAY TUESDAY...LASTING THROUGH THE REST OF THE FORECAST. /16 && .AVIATION...18Z ISSUANCE...LIGHT SOUTHERLY FLOW WILL CONTINUE THROUGH THE PERIOD. WINDS NEAR AND JUST ABOVE THE SURFACE WILL BE LIGHT ENOUGH TO HOLD BACK EXTENSIVE FOG DEVELOPMENT...WINDS ABOVE 1000FT WILL BE HIGH ENOUGH FOR STRATUS/CU TO FORM AGAIN TONIGHT. A BETTER CHANCE FOR PRECIP EXISTS SUNDAY...EVEN MORE MONDAY AS A SURFACE BOUNDARY SAGS TOWARDS THE AREA. /16 && .FIRE WEATHER...NO CONCERNS. AFTERNOON RELATIVE HUMIDITIES WILL REMAIN WELL ABOVE CRITICAL THRESHOLDS THROUGH NEXT WEEK. /29 && .PRELIMINARY POINT TEMPS/POPS... MOBILE 69 89 69 84 / 10 20 10 50 PENSACOLA 70 87 70 84 / 10 10 10 40 DESTIN 72 85 71 83 / 10 10 10 40 EVERGREEN 66 88 66 81 / 10 20 20 60 WAYNESBORO 65 86 62 78 / 20 30 20 60 CAMDEN 66 85 65 79 / 20 30 30 60 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...NONE. FL...NONE. MS...NONE. GM...NONE. && $$