000 FXUS62 KMLB 100235 AFDMLB AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 935 PM EST THU FEB 9 2012 .DISCUSSION... ...RAIN CHANCES INCREASING FRIDAY AND FRIDAY NIGHT... ...TURNING SHARPLY COLDER THIS WEEKEND... ...POOR TO HAZARDOUS BOATING CONDITIONS DEVELOPING FRI NIGHT-SAT... CURRENTLY-TONIGHT...PRECIPITABLE WATER ON EVENING SOUNDINGS IN CENTRAL FLORIDA ACTUALLY DECREASED FROM 12Z AS A WEAK IMPULSE ALOFT PASSED BY TO OUR EAST. ISENTROPIC LIFT WILL START TO INCREASE LATE TONIGHT WELL AHEAD OF SHORTWAVE TROUGH PUSHING THROUGH THE SOUTHERN PLAINS...BUT IT WILL TAKE AWHILE TO MOISTEN THE DRY LAYER JUST ABOVE THE SURFACE...ESPECIALLY CENTRAL/NORTH. ONSHORE MOVING SHOWERS ARE PRESENTLY JUST STARTING TO GRAZE MARTIN COUNTY WITH MORE COVERAGE TO THE SOUTH. EXPECT SHOWERS TO EXPAND NORTH AND START TO AFFECT MORE OF THE TREASURE COAST AFTER MIDNIGHT AND THE SPACE COAST BEFORE SUNRISE. PRESENT RADAR TRENDS SUGGEST NUDGING POPS ALONG THE MARTIN/ST LUCIE COAST TO 30 PERCENT. SOME BREAKS IN THE CLOUD COVER HAVE DEVELOPED BUT WITH LOW LEVEL ISENTROPIC LIFT DEVELOPING AND UPSTREAM MID-HIGH LEVEL CLOUDS WILL KEEP CONSIDERABLE CLOUDINESS WORDING. ONSHORE FLOW WILL KEEP TEMPS MORE MILD THAN LAST NIGHT AND HAVE NUDGED UP READINGS A DEGREE OR TWO ALONG THE COAST. PREVIOUS DISCUSSION FOR FRI... LOW LEVEL MOISTURE WILL CONTINUE TO RETURN NORTHWARD AND PRODUCE MULTI-LAYERED CLOUDS AND SHOWERS. HAVE INTRODUCED THUNDER FOR THE COAST FROM BREVARD SOUTHWARD ON THE SLIM CHANCE THERE COULD BE SOME BREAKS IN THE CLOUDS AND ENOUGH INSTABILITY AND CYCLONIC CONVERGENCE TO GENERATE DEEP CONVECTION. THE GFS IS MORE AGGRESSIVE WITH RAINFALL THAN ECWMF ACROSS THE SOUTH AND ALONG BREVARD COAST BUT GFS IS NOT VERIFYING WELL THIS AFTN WITH ITS QPF FORECAST. HAVE INCREASED RAIN CHANCES TO 70 PERCENT ALONG THE TREASURE COAST WHERE WE THINK THE BEST CHANCE FOR LOCALLY HEAVY RAIN AND THUNDER EXISTS...FOLLOWED BY BREVARD/INDIAN RIVER (60 PERCENT)...TAPERING BACK TO 30 PERCENT LAKE COUNTY. MAX TEMPS IN THE MID 70S LAKE/VOLUSIA TO AROUND 80 SOUTHERN COUNTIES ESP IF THERE IS SOME HEATING. RAINFALL AMOUNTS THROUGH FRIDAY SHOULD AVERAGE LESS THAN ONE QUARTER INCH EXCEPT PERHAPS COASTAL MARTIN/ ST LUCIE COUNTIES. && .AVIATION... A FEW POCKETS OF MVFR CEILINGS ARE OCCURRING AND EXPECT THESE TO EXPAND OVERNIGHT AND BECOME PREVAILING AROUND MIDNIGHT IN THE SOUTH AND ACROSS THE NORTH AROUND SUNRISE FRIDAY. SHOWERS OVER SOUTH FLORIDA WILL EXPAND ACROSS THE SOUTHERN TERMINALS OVERNIGHT AND TO THE CENTRAL/NORTH COAST AFTER SUNRISE FRI. THERE IS A CHANCE FOR IFR VISIBILITIES TO DEVELOP...BUT DID NOT INCLUDE IN THE TEMPO GROUPS YET. IT SHOULD TAKE LONGER FOR THE SHOWERS TO AFFECT INLAND TERMINALS... BUT MODELS SHOW GREATEST LARGE SCALE LIFT OCCURRING FRI AFTERNOON SO THINK THAT WILL BE WHEN CEILINGS/VISIBILITIES WILL BE LOWEST AND MOST WIDESPREAD THERE. && .MARINE... TONIGHT/FRI...THE LATEST SURFACE ANALYSIS/OBSERVATIONS SHOW THAT EAST WINDS ACROSS THE SOUTH ARE STILL 15-20 KNOTS OFFSHORE...SO WILL HOLD ONTO THE EXERCISE CAUTION OVER NIGHT. SURFACE TROUGH IS FORECAST TO FORM VICINITY OF THE PENINSULA ON FRI. THIS SHOULD CAUSE THE GRADIENT TO WEAKEN NEAR THE COAST...BUT SOUTHEAST WINDS MAY STAY AROUND 15 KNOTS OFFSHORE. A RATHER LARGE AREA OF SHOWERS SHOULD START TO AFFECT THE SOUTH EARLY IN THE MORNING AND GRADUALLY EXPAND NORTHWARD OVER MUCH OF THE WATERS DURING THE AFTERNOON. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM/AVIATION...LASCODY IMPACT WEATHER...SEDLOCK/GUSEMAN