Key West forecast discussion:
FLORIDA KEYS AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
330 PM EDT SAT JUL 1 2006
.DISCUSSION...
.CURRENTLY...
A BIT UNSETTLED THIS AFTERNOON AS KBYX RADAR INDICATES SEVERAL SMALL
CLUSTERS OF SHOWERS AND THUNDERSTORMS PROPAGATING IN SYNCHRONIZATION
WITH SHORT OUTFLOW BOUNDARIES. AS OF 1845Z THE SHOWERS WERE MOST
PREVALENT FROM OFFSHORE LONG KEY THROUGH MARATHON/SEVEN MILE BRIDGE
AND EMERGING OUT INTO THE GULF WITHIN 20NM OF THE LOWER KEYS. OTHER
CLUSTERS HAVE BEEN BRIEFLY VIGOROUS BEYOND 50NM OFFSHORE THE MIDDLE
AND UPPER KEYS. EAST WINDS HAVE FRESHENED TO AROUND 15 MPH WITH
GUSTS ABOVE 20 MPH...WITH GUSTS IN THE SHOWERS EXCEEDING 25 KNOTS AT
TIMES. TEMPERATURES ACTUALLY PEAKED AT 89F AT KEY WEST...BUT NEARBY
SHOWERS AND INCREASING CONVECTIVE DEBRIS HAS DROPPED TEMPERATURES
INTO THE MID 80S. DEWPOINTS HAVE INCREASED INTO THE MID 70S.
DEWPOINTS IN THE UPPER 70S LURK ALONG COASTAL SECTIONS OF CUBA AND
IN THE CENTRAL BAHAMAS.
.FORECAST...
THE UPPER TROPOSPHERIC STORY IS TOLD BY A STRONG MID TO UPPER RIDGE
ACROSS THE NORTHWEST CARIBBEAN...WITH A VERY POSITIVE TILT SHORTWAVE
THROUGH THE EASTERN SEABOARD. OVER TIME...THE SOUTHERN END OF THE
UPPER TROUGH IS EXPECTED TO BE LEFT BEHIND OFF THE GEORGIA COAST AND
POSSIBLE CUT OFF. LATE IN THE WEEK MORE ENERGY SINKS INTO THE MID
ATLANTIC AND BOOTS OUT THE WEAKNESS. WHILE THE UPPER HIGH SLIPS WEST
TOWARD THE SOUTHERN GULF LATE IN THE WEEK...NO SIGNIFICANT UPPER
FEATURES ARE EXPECTED TO RETROGRADE THROUGH THE KEYS. BELOW...A
SURFACE RIDGE HAS BEEN STRENGTHENING ACROSS THE SOUTHEAST U.S. THE
NORTHERN EXTENSION OF A TROPICAL WAVE REACHES NORTHEAST THROUGH THE
NORTHWEST BAHAMAS. ONLY THE NORTHERN PORTION IS ACTIVE AS IT
INTERACTS WITH STRONGER WESTERLIES...GOOD VENTILATION FOR
CONVECTION. THE TROUGH ASSOCIATED WITH THE WAVE IS NOT VERY WELL
DEFINED IN TERMS OF ISOBARS...AND IT MAINLY HERALDS INCREASED EAST
TO SOUTHEAST FLOW IN THE LOW ALTITUDES CONTRIBUTING TO BETTER
MOISTURE CONVERGENCE AND ARRIVAL OF HIGHER THETA-E ATMOSPHERE.
PRECIPITABLE WATER IS EXPECTED CLIMB HIGHER TO NEAR 2.2 INCHES PER
GFS AND NAM MODEL SOUNDINGS BY SUNDAY. THERE IS SOME
DIVERGENCE...BUT NOT PARTICULARLY STRONG...FAVORING BEST LIFT ACROSS
THE EASTERN WATERS THROUGH THE NORTHERN BAHAMAS. DIFFERENCES ARISE
IN THE MORE AGGRESSIVE AND CONCENTRATED NAM VS THE MORE OPEN GFS
SOLUTION. GFS MOS POPS HAVE DROPPED WHILE NAM POPS HAVE SKYROCKETED.
WITH THE INCREASED MOISTURE...CONVERGENCE FROM NUMEROUS MESOSCALE
BOUNDARIES IN ADDITION TO THE BROADER CONVERGENCE WITH THE
TROUGH...AND SLIGHT TURNING OF WINDS TO SOUTHEAST BELOW 15000
FEET...EXPECTING GREATER COVERAGE OF SHOWERS AND THUNDERSTORMS. IN
THE WAKE OF THE SURFACE TROUGH PASSAGE...RIDGE TO THE NORTH WILL
KEEP THE PRESSURE GRADIENT TIGHT ENOUGH FOR MODERATE EAST WINDS
UNTIL MIDDLE OF NEXT WEEK. THEREAFTER THE WEST ATLANTIC RIDGE
WEAKENS DUE TO THE LATE WEEK UPPER TROUGH MOVING THROUGH THE
NORTHEAST...AND THE WEAKENED RIDGE AXIS SLIPS BACK DOWN THE
PENINSULA.
FOR TONIGHT THROUGH SUNDAY NIGHT...BOOSTED POPS TO HIGH CHANCE
TONIGHT AND LIKELY FOR SUNDAY AND SUNDAY NIGHT AS THE MAXIMUM
CONVERGENCE ASSOCIATED WITH THE SURFACE TROUGH MOVES INTO THE AREA.
EXPECT GUSTY WINDS NEAR 15 MPH. WHILE THE DOWNPOURS MAY OCCUR
SEVERAL TIMES...FAST MOVEMENT OF THE SHOWERS WILL KEEP RAINFALL
TOTALS IN CHECK. KEPT THE TOTAL 24-HR QPF FOR MONDAY BELOW ONE HALF
INCH FOR A KEYS AVERAGE.
MONDAY THROUGH TUESDAY NIGHT...WINDS WILL GRADUALLY SLACKEN AND
BECOME MORE SOUTHEASTERLY. MOIST AIRMASS WILL CONTINUE...BUT LACK OF
SIGNIFICANT SYNOPTIC PRECLUDE THE LIKELY POPS THAT MOS GUIDANCE HAS
PROJECTED. JUST KNOW THE DRYING PROCESS WILL BE SLOW WITH THE LIGHT
SOUTHEAST WINDS.
WEDNESDAY THROUGH SATURDAY...MAINTAINED CLIMATOLOGICAL POPS NEAR 30
PERCENT AND NORMAL SUMMERTIME WEATHER. WINDS WILL BE LIGHT OUT OF
THE SOUTHEAST AS THE SURFACE RIDGE AXIS WEAKENS AND SINKS THROUGH
THE FLORIDA PENINSULA.
&&
.MARINE...
MARINERS SHOULD CHECK THE WEATHER PRIOR TO DEPARTURE AND CHECK WITH
NOAA WEATHER RADIO DUE TO INCREASING SHOWERS AND THUNDERSTORMS LATE
TONIGHT THROUGH SUNDAY EVENING. THE MAIN IMPACTS FROM THE STRONGER
STORMS WILL BE BRIEFLY VERY POOR VISIBILITY AND FREQUENT DANGEROUS
LIGHTNING STRIKES. A FEW MAY PRODUCE WIND GUSTS TO 35 KNOTS AS WELL.0
THE PRESSURE GRADIENT DUE TO THE APPROACHING SURFACE TROUGH FROM THE
EAST AND A STRENGTHENING RIDGE TO THE NORTH...ALONG WITH THE
GUSTINESS FROM COOL OUTFLOW FROM NUMEROUS SHOWERS...WILL MAKE IT A
BIT DICEY ON THE STRAITS THE NEXT COUPLE DAYS. RECOMMENDING SMALL
CRAFT EXERCISE CAUTION AS WINDS EXPECTED TO EXCEED 15 KNOTS WITH
FREQUENT GUSTS ABOVE 20 KNOTS. SEAS WILL BUILD TO 6 FEET...EVEN
HIGHER IN THE GULF STREAM...FROM EARLY SUNDAY THROUGH SUNDAY NIGHT.
THEREAFTER SLACKENING OF THE PRESSURE GRADIENT WILL ALLOW THE EAST
WINDS TO DROP TO 15 KNOTS OR LESS MONDAY THROUGH THE REST OF THE
WORK WEEK.
&&
Radar:
http://radar.weather.gov/ridge/radar.php?rid=amx&product=N0R&overlay=11101111&loop=no
