EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1124 AM EDT SAT JUN 01 2013

VALID 12Z TUE JUN 04 2013 - 12Z SAT JUN 08 2013

...MULTI-DAY HEAVY RAINFALL THREAT FOR SOUTH FLORIDA...

RELIED ON THE 06Z/01 GEFS MEAN MASS FIELDS AS A GUIDE FOR THE
FRONTS AND PRESSURES FOR DAYS 3 THROUGH 7, CHOSEN BECAUSE IT BEST
REPRESENTED CONTINUITY AND THE GROWING CERTAINTY IN SOME OF THE
SYNOPTIC SYSTEMS POSING THE GREATEST SENSIBLE WEATHER THREATS. ALL
THE GLOBAL NUMERICAL MODELS INDICATE THE CONTINUATION OF AN
UNSEASONABLY SUPPRESSED POLAR JET ACROSS THE UNITED STATES AT THE
MEDIUM RANGE--ATTENDANT TO THE AT LEAST MODEST ONGOING BLOCKING AT
HIGH LATITUDES. THE MEAN TROUGH IS EXPECTED TO BE ANCHORED OVER
THE MIDDLE OF THE NATION, AND THAT IS WHERE THE WIDEST SPREAD
RAINFALL IS ANTICIPATED THIS PERIOD.

SUPER-MOISTURE-PACKED
TROPICAL AIR CIRCULATING AROUND A DEEP-LAYER VORTEX OVER THE GULF
OF MEXICO IS EXPECTED TO WASH INTO SOUTHERN FLORIDA AS THE PASSAGE
OF A SHORTWAVE TROUGH ACROSS THE EASTERN UNITED STATES ELONGATES
THE GULF CIRCULATION. ALL THE MODELS BREAK OFF A CHUNK OF THIS
TROPICAL SWIRL AND TRACK IT ACROSS THE FLORIDA PENINSULA, THEN UP
THE SOUTHERN EDGE OF THE POLAR WESTERLIES ALONG THE SOUTHEAST
COAST. THE GEM GLOBAL CONTINUES TO PRESENT AN UNREALISTIC
EMERGENCE OF A FULL-BLOWN TROPICAL CYCLONE VERY EARLY IN THE
PERIOD, TRACKING IT ACROSS FLORIDA THEN UP THE ATLANTIC COAST
PLAIN--DIRECTLY ASTRIDE THE BAROCLINIC ZONE IN PLACE. THE MOST
LIKELY OUTCOME IS A JUICY FRONTAL WAVE THAT SHOULD KEEP MOST OF
THE HIGHEST MOISTURE-CONTENT AIR EAST OF THE ATLANTIC COAST NORTH
OF JACKSONVILLE, FLORIDA. THE 0.25KM ECMWF PUSHES A SLUG OF 2.50+"
PRECIPITABLE WATER-LADEN AIR ACROSS SOUTHERN FLORIDA, INCLUDING
THE KEYS, NEXT WEDNESDAY THROUGH THURSDAY, SUPPORTING MANY INCHES
OF RAINFALL ACROSS THE AREA. WILL BE COORDINATING WITH THE
NATIONAL HURRICANE CENTER ON THE FIRST MEDIUM-RANGE HOTLINE CALL
OF THE YEAR EARLY THIS AFTERNOON TO DISCUSS ANY TROPICAL CYCLONE
POTENTIAL WITH THIS SYSTEM, AS WELL AS ANY OTHERS OVER THE NEARBY
OCEANS.

CISCO