FXUS64 KMOB 150503
AFDMOB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
1100 PM CST MON DEC 14 2009
.MESOSCALE UPDATE...THIS EVENING HAS BEEN CHARACTERIZED BY YET
ANOTHER ROUND OF VERY HEAVY RAINFALL ACROSS THE AREA. FLOODING HAS
BEEN WIDESPREAD FROM MOBILE COUNTY NORTHEAST ALL THE WAY INTO
CRENSHAW COUNTY. THE SIMPLE FACT IS THAT WE CANNOT TAKE ANY MORE
WATER AT THIS JUNCTURE GIVEN WHAT HAS HAPPENED THIS EVENING COMBINED
WITH THE HEAVY RAIN EVENT FROM JUST A FEW DAYS AGO. UNFORTUNATELY...
IT LOOKS LIKE MUCH MORE IS ON THE WAY.
AN OUTFLOW BOUNDARY HAS SURGED SOUTH AND IS NOW LOCATED OFFSHORE.
WHILE THIS HAS ENDED THE SFC BASED CONVECTION FOR THE TIME BEING...A
LARGE AREA OF STRATIFORM RAIN WITH EMBEDDED THUNDER NOW BLANKETS
MUCH OF THE CWA. THIS IS DUE TO INCREASING WARM AIR ADVECTION...
AIDED BY A 30 KT 850 MB LOW LEVEL JET...RIDING ATOP THE NOW
INCREASINGLY STABLE SFC LAYER. WE ARE ALSO SEEING RENEWED
DEVELOPMENT ACROSS LOUISIANA AND SW MISSISSIPPI...AS THE CONVECTIVE
OUTFLOW BEGINS TO BUCKLE AND LIFT BACK TO THE NORTH. PRECIP IS ALSO
BEING GENERATED BY A DEPARTING 120 KT JET MOVING INTO THE TN AND OH
VALLEYS. LOW TO MID LEVEL TRAJECTORIES SHOW THAT THIS PRECIP HAS
NOWHERE TO HEAD EXCEPT IN OUR DIRECTION. THEREFORE...WE ARE
EXPECTING MODERATE TO HEAVY RAIN WITH EMBEDDED THUNDER TO PERSIST
OVERNIGHT. THEREFORE...THE FLOODING THREAT WILL CONTINUE.
IT DOES NOT LOOK TO GET ANY BETTER TOMORROW UNFORTUNATELY. THE COLD
FRONT IS EXPECTED TO BEGIN MOVING IN THE AREA BY 12Z...MOVING
OFFSHORE BY LATE AFTN. BY 12Z...A VERY POWERFUL 130+ KT UPPER LEVEL
JET CURRENTLY OVER THE BAJA WILL BEGIN TO NOSE INTO THE AREA. AS THE
SFC-850 MB FRONT MOVES THROUGH AND THE JET NOSES IN...FRONTOGENESIS
WILL BECOME FURTHER ENHANCED...AND ISENTROPIC LIFT BEHIND THE
BOUNDARY WILL ALSO INCREASE. THEREFORE...WE ARE EXPECTING PERIODS OF
HEAVY RAIN TO CONTINUE THROUGH TUESDAY AFTERNOON. THIS WILL ONLY
FURTHER EXACERBATE THE FLOODING PROBLEM...ESPECIALLY CONSIDERING
PRECIPITABLE WATERS START OFF AT 1.6-1.8 INCHES. AN ADDITIONAL 3 TO
5 INCHES OF RAIN WITH LOCALLY HIGHER TOTALS IS NOT OUT OF THE
QUESTION THROUGH 00Z WED.
MORE INFORMATION TO COME WITH THE EARLY MORNING PACKAGE. 34/JFB
&&
.AVIATION...
06 TAF CYCLE.
IFR TO LIFR CONDITIONS EXPECTED THROUGH MAJORITY OF THE TAF PERIOD
WITH PERIODS OF MODERATE TO HEAVY RAIN AND EMBEDDED THUNDER. A COLD
FRONT WILL MOVE THROUGH DURING THE DAY TUESDAY...BRINGING A WIND
SHIFT TO THE NORTH. 34/JFB
/PREVIOUS DISCUSSION ISSUED 310 PM/
.SHORT TERM...(TONIGHT THROUGH WEDNESDAY)...WET PATTERN WILL
CONTINUE THROUGH TUESDAY AS A COLD FRONT SLOWLY APPROACHES THE AREA.
THE WARM FRONT HAS NOW LIFTED NORTH OF THE AREA WITH MOST OBS IN
SOUTHWEST ALABAMA INDICATING TEMPERATURES AND DEWPOINTS IN THE LOW
70S. LIGHT SOUTHERLY FLOW WILL CONTINUE TO PUMP MOISTURE INTO THE
AREA TONIGHT WITH PW VALUES INCREASING TO ABOVE 1.75 INCHES.
DIFFLUENT UPPER FLOW COMBINED WITH SEVERAL UPPER LEVEL DISTURBANCES
MOVING EASTWARD ACROSS THE AREA WILL TAP INTO THE MOIST AIRMASS AND
GENERATE HEAVY RAIN THROUGH TUESDAY MORNING. ANOTHER 2 TO 4 INCHES
OF RAIN IS POSSIBLE AND THIS WILL EASILY CAUSE FLOODING AS THE
GROUND IS ALREADY SATURATED WITH MANY CREEKS AND RIVERS NEAR OR
ABOVE FLOOD STAGE. A FLASH FLOOD WATCH REMAIN IN EFFECT FOR THE
ENTIRE AREA THROUGH TUESDAY AFTERNOON. DENSE FOG WILL ALSO REMAIN A
THREAT PARTICULARLY NEAR THE COAST AND ADJACENT COASTAL WATERS. THE
COLD FRONT WILL FINALLY MOVE ACROSS THE AREA TUESDAY MORNING THROUGH
TUESDAY AFTERNOON BRINGING A MUCH COOLER AND DRIER AIRMASS BACK INTO
THE REGION. THIS WILL RETURN TEMPERATURES BACK TO NEAR NORMAL FOR
THIS TIME OF YEAR FOR TUESDAY NIGHT AND WEDNESDAY. /13
.LONG TERM...(THURSDAY THROUGH SUNDAY)...THE ECMWF AND GFS BOTH
DEVELOP A GULF LOW ON THURSDAY AND MOVE IT EASTWARD ACROSS THE NORTH
CENTRAL GULF THURSDAY AFTERNOON INTO FRIDAY. THE ECMWF IS STRONGER
AND FARTHER TO THE NORTH WITH THIS LOW...WHICH WOULD HAVE MORE OF AN
IMPACT ON OUR AREA. MEANWHILE THE GFS IS WEAKER AND FARTHER TO THE
SOUTH...THUS KEEPING MOST OF THE HEAVIER RAIN SOUTH AND EAST OF THE
GULF COAST. FOR NOW WILL MAINTAIN THE SLIGHT CHANCE POPS IN THE
ONGOING FORECAST FOR THIS TIME PERIOD WITH THE CAVEAT THAT HIGHER
POPS MAY BE NEEDED IF THE ECMWF SOLUTION IS CORRECT. IN THE WAKE OF
THE GULF LOW...A LONGWAVE TROUGH DEEPENS OVER THE EASTERN STATES AND
SENDS A COLDER AND DRIER AIRMASS ACROSS THE CENTRAL GULF COAST FOR
THE WEEKEND INTO EARLY NEXT WEEK. THIS WILL DROP TEMPERATURES TO
BELOW NORMAL WITH SOME LOWS AROUND THE FREEZING MARK FRIDAY AND
SATURDAY NIGHT. /13
&&
.MARINE...WILL KEEP THE DENSE FOG ADVISORY OVER THE BAYS AND NEAR
SHORE WATERS THROUGH TUESDAY MORNING. DON'T EXPECT MUCH...IF ANY
IMPROVEMENT UNTIL THE COLD FRONT ARRIVES LATE MORNING TUESDAY. NOT A
LOT OF REPORTS FROM THE MARINE AREA BUT LOCAL WEB CAMS ALONG THE
BEACHES SHOW LOW VISIBILITY. WINDS WILL INCREASE AFTER THE COLD
FRONT AND SHOULD INCREASE TO SMALL CRAFT ADVISORY LEVELS BY TUESDAY
EVENING. FOR NOW WILL JUST MENTION IN SYNOPSIS. ANOTHER LOW PRESSURE
CENTER IS FORECAST TO DEVELOP AND MOVE EAST ACROSS THE NORTH CENTRAL
GULF LATER IN THE WEEK. THIS WILL INTERACT WITH THE SURFACE HIGH
THAT WILL BE MOVING EAST ACROSS THE SOUTHERN STATES FOLLOWING THE
TUESDAY COLD FRONT AND KEEP THE WINDS NORTH TO NORTHEAST AND AROUND
OR ABOVE SMALL CRAFT LEVELS THROUGH THE WEEK. /11
&&
.PRELIMINARY POINT TEMPS/POPS...
MOBILE 61 63 41 62 / 90 90 20 00
PENSACOLA 64 68 46 63 / 90 90 30 05
DESTIN 64 69 48 64 / 70 80 40 05
EVERGREEN 59 62 38 60 / 90 90 20 05
WAYNESBORO 53 57 36 57 / 80 80 10 05
CAMDEN 57 59 37 58 / 90 80 10 05
CRESTVIEW 62 67 45 65 / 80 90 30 05
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...DENSE FOG ADVISORY UNTIL 8 AM TUESDAY FOR THE FOLLOWING ZONES:
LOWER BALDWIN...AND LOWER MOBILE.
FLASH FLOOD WATCH UNTIL 6 PM TUESDAY FOR THE FOLLOWING ZONES:
BUTLER...CHOCTAW...CLARKE...CONECUH...COVINGTON...
CRENSHAW...ESCAMBIA...LOWER BALDWIN...LOWER MOBILE...
MONROE...UPPER BALDWIN...UPPER MOBILE...WASHINGTON...AND
WILCOX.
FL...FLASH FLOOD WATCH UNTIL 6 PM TUESDAY FOR THE FOLLOWING ZONES:
COASTAL ESCAMBIA...COASTAL OKALOOSA...COASTAL SANTA ROSA...
INLAND ESCAMBIA...INLAND OKALOOSA...AND INLAND SANTA ROSA.
DENSE FOG ADVISORY UNTIL 8 AM TUESDAY FOR THE FOLLOWING ZONES:
COASTAL ESCAMBIA...COASTAL OKALOOSA...AND COASTAL SANTA
ROSA.
MS...FLASH FLOOD WATCH UNTIL 6 PM TUESDAY FOR THE FOLLOWING ZONES:
GEORGE...GREENE...PERRY...STONE...AND WAYNE.
GM...DENSE FOG ADVISORY UNTIL 6 AM TUESDAY FOR THE FOLLOWING ZONES:
COASTAL WATERS FROM DESTIN TO PENSACOLA FL OUT 20 NM...
COASTAL WATERS FROM PENSACOLA FL TO PASCAGOULA MS OUT 20
NM...AND MOBILE BAY.
&&
$$
