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000 FXUS62 KMFL 151510 AAA AFDMFL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIAMI FL 1010 AM EST SUN FEB 15 2009 .UPDATE...UPDATED TO ALLOW BOTH, DENSE FOG ADVISORIES OVER AND GULF WATERS/LAKE OKEECHOBEE TO EXPIRE. SFC OBS AND SATELLITE IMAGES INDICATED IMPROVING CONDITIONS. HOWEVER, WILL STILL KEEP PATCHY FOG OVER THE GULF OF MEX WATERS THROUGH REST OF THE MORNING AND EARLY AFTERNOON. REST OF THE FORECAST PACKAGE STILL ON TRACK. .......................PREVIOUS DISCUSSION...................... .AVIATION... WIDESPREAD FOG CONTINUES ACROSS SOUTH FL WITH DENSE FOG IN MANY AREAS. FOG WILL IMPACT ALL TERMINALS EARLY THIS MORNING BUT BURN OFF A FEW HOURS AFTER SUNRISE. A FEW SHRA MAY IMPACT EAST COAST TERMINALS AS SEA BREEZE MOVES INLAND MID DAY/THIS AFTERNOON. W COAST SEA BREEZE COULD BRING FOG BACK INTO KAPF LATE THIS AFTERNOON. SOME CHANCE FOR FOG OTHER TERMINALS AGAIN TONIGHT AHEAD OF COLD FRONT BUT CLOUDS MAY LIMIT COVERAGE. /STRASSBERG && .PREV DISCUSSION... /ISSUED 526 AM EST SUN FEB 15 2009/ DISCUSSION... ANOTHER FOGGY NIGHT IS CURRENTLY IN PROGRESS ACROSS SOUTH FLORIDA...WITH STRATUS DECK THAT MOVED INLAND FROM THE SOUTHEASTERN GULF OF MEXICO ON SATURDAY EVENING NOW BUILDING DOWN AS WIDESPREAD DENSE FOG ACROSS MUCH OF THE AREA. ACROSS THE EAST COAST...RESIDUAL MOISTURE FROM RAINFALL YESTERDAY AND SMOKE FROM WILDFIRES IN THE EVERGLADES IS RESULTING IN DENSE FOG DEVELOPMENT ACROSS THIS REGION AS WELL. EXPECT CONDITIONS TO IMPROVE FOR ALL LOCATIONS...WITH THE EXCEPTION OF THE GULF WATERS AND IMMEDIATE COASTAL LOCATIONS...BY MID-MORNING. SHORT TERM MODELS AGREE THAT INFLUENCE OF STRONG MID/UPPER-LEVEL RIDGE EXTENDING FROM CENTRAL AMERICA ACROSS THE CARIBBEAN SEA WILL REMAIN SUPPRESSED FOR AT LEAST THE NEXT 24-36 HOURS... ALLOWING FOR A SLIGHT IMPROVEMENT IN CHANCES FOR MUCH NEEDED RAINFALL. IT NOW APPEARS THAT PRESSURE GRADIENT TODAY WILL REMAIN WEAK ENOUGH TO ALLOW ATLANTIC COAST SEA BREEZE TO PENETRATE INLAND THIS AFTERNOON...AND BASED ON COVERAGE OF SHOWER ACTIVITY SATURDAY...DEEPER MOISTURE ANTICIPATED LATER TODAY...AND PRESENCE OF WEAK SHEAR AXIS ALOFT APPROACHING REGION FROM THE CENTRAL GULF...EXPECT AT LEAST SCATTERED SHOWERS TO DEVELOP OVER THE INTERIOR BY LATE AFTERNOON. WEST-SOUTHWESTERLY STEERING FLOW WILL ALLOW THIS ACTIVITY TO MOVE BACK TOWARD THE EAST COAST EARLY THIS EVENING...AND WILL INCREASE POPS TO ACCOUNT FOR THIS. MEANWHILE...AN UPPER-LEVEL VORT MAX DIGGING EAST-SOUTHEASTWARD OVER THE TENNESSEE VALLEY WILL RESULT IN SURFACE CYCLOGENESIS OFF THE ATLANTIC COAST OF NORTHEAST FLORIDA LATE TONIGHT...ALLOWING COLD FRONT TO BEGIN MOVING SOUTHEASTWARD TOWARD THE AREA. EXPECT FRONT TO EXTEND ROUGHLY ALONG THE APF-PBI CORRIDOR AROUND 12Z MONDAY...WITH HIGHEST POPS IN THIS REGION. FRONT SHOULD MOVE STEADILY SOUTHWARD OVER THE REGION BETWEEN 12-18Z MONDAY...WITH SHOWER THREAT CONFINED TO THE NORTHEAST PORTION OF THE FORECAST AREA AND ATLANTIC WATERS DURING TIME OF FRONTAL PASSAGE. EXPECT BRISK NORTH TO NORTHEAST WINDS AND MODERATE COLD ADVECTION TO OCCUR FOR REMAINDER OF THE DAY ON MONDAY AND MONDAY NIGHT...BEFORE SURFACE HIGH SHIFTS EASTWARD OFF THE COAST OF THE MID-ATLANTIC ON TUESDAY...RESULTING IN A RETURN TO EASTERLY FLOW. RETURN FLOW PATTERN WILL CONTINUE IN THE EXTENDED PORTION OF THE FORECAST...AS GLOBAL MODELS AGREE THAT A POWERFUL UPPER LOW CURRENTLY SITUATED OFF THE COAST OF CALIFORNIA WILL SPREAD EASTWARD ACROSS THE CENTRAL ROCKIES AND INDUCE SURFACE CYCLOGENESIS OVER THE CENTRAL PLAINS BY MID-WEEK. ALTHOUGH MOISTURE WILL BE INCREASING THROUGH THE PERIOD AS WINDS VEER TO SOUTHEAST...UPPER-LEVEL RIDGE TO THE SOUTH OF THE AREA WILL BUILD NORTHWARD IN ADVANCE OF THIS FEATURE...MAINTAINING GENERALLY DRY CONDITIONS. AMPLIFICATION OF THE LONG WAVE PATTERN ACROSS NORTH AMERICA IS STILL ANTICIPATED BY THE END OF THE WEEK...AS PREVIOUSLY MENTIONED SYSTEM EJECTS NORTHEASTWARD AND A PAIR OF UPPER LOWS DROP SOUTHEASTWARD OVER THE EASTERN HALF OF THE COUNTRY. COLD FRONT ASSOCIATED WITH THIS SYSTEM IS EXPECTED TO ARRIVE IN SOUTH FLORIDA ON THURSDAY NIGHT OR FRIDAY MORNING...WITH POTENTIAL FOR A FEW SHOWERS ALONG FRONT AND A MUCH COOLER/DRIER AIRMASS FOR THE END OF THE WEEK. MARINE... DENSE FOG IS ONCE AGAIN THE MOST SIGNIFICANT MARINE CONCERN THIS MORNING...WITH DENSE FOG ADVISORY IN EFFECT THROUGH 10 AM EST FOR THE LOCAL GULF WATERS AND LAKE OKEECHOBEE. OTHERWISE...EXPECT NORTH WINDS TO INCREASE TO AROUND 20 KNOTS OVER THE ATLANTIC/GULF FOLLOWING PASSAGE OF COLD FRONT ON MONDAY...WITH 15-20 KNOTS ANTICIPATED ON THE LAKE AND BISCAYNE BAY. WILL CONTINUE TO CAP GULF STREAM SEAS AT 8 FEET...GIVEN SHORT DURATION OF HIGH WINDS AND FLOW VEERING QUICKLY TO NORTHEAST. ANOTHER FRONTAL PASSAGE ON THURSDAY NIGHT/FRIDAY MORNING WILL RESULT IN SIMILAR MARINE CONDITIONS BY THE END OF THE WEEK. FIRE WEATHER... MINIMUM AFTERNOON RH VALUES MAY FALL TO AROUND 35-40 PERCENT ACROSS THE NORTHWEST INTERIOR ON MONDAY AND TUESDAY AFTERNOONS. HOWEVER...A MORE SIGNIFICANT AND WIDESPREAD FIRE WEATHER CONCERN WILL COME ON FRIDAY AND SATURDAY AFTERNOONS...FOLLOWING THE PASSAGE OF A STRONGER FRONT ON THURSDAY NIGHT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 80 62 74 55 / 20 30 30 10 FORT LAUDERDALE 81 64 76 59 / 20 20 20 10 MIAMI 81 64 77 58 / 10 10 20 10 NAPLES 78 62 76 52 / 10 30 20 - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...DENSE FOG ADVISORY UNTIL 9 AM EST THIS MORNING FOR FLZ063-FLZ066- FLZ067-FLZ068-FLZ069-FLZ070-FLZ071-FLZ072-FLZ073-FLZ074- FLZ075-FLZ168-FLZ172-FLZ173-FLZ174. AM...NONE. GM...NONE. && $$ LONG TERM...70/DD SHORT TERM/AVIATION...65/GS