Area Forecast Discussion
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000
FXUS62 KKEY 190904
AFDKEY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KEY WEST FL
504 AM EDT SUN APR 19 2015

.DISCUSSION...A DEEP ANTICYCLONIC CIRCULATION PREVAILS ACROSS THE
WESTERN CARIBBEAN DESPITE THE ENCROACHMENT OF A STRONG SUBTROPICAL
JET INTO THE WESTERN GULF OF MEXICO. THE JET STREAM RELEASES TO THE
NORTH INTO THE MISSISSIPPI RIVER VALLEY...DEFLECTED BY THE DEEP RIDGE
COMPLEX. AT THE SURFACE...A BROAD AND MULTI-CENTERED LOW PRESSURE
SYSTEM IS DEVELOPING ACROSS THE SOUTHERN PLAINS. THE ATLANTIC RIDGE
SURVIVES ACROSS THE BAHAMAS AND THE SOUTHERN FLORIDA PENINSULA.

.CURRENTLY...THE AREA C-MANS DETECT MODERATE...WARM..AND HUMID
SOUTHEAST BREEZES. TEMPERATURES ALONG THE ISLAND CHAIN HAVE BARELY
DIPPED PAST 80 DEGREES. SKIES ARE LITTERED BY THE DEBRIS OF HIGHER
CLOUDS...YET ARE MOSTLY VOID OF LOW-LEVEL CUMULUS. THE RADAR IS ECHO
FREE.

.SHORT TERM (TODAY THROUGH TUESDAY)...THE DEVELOPING CYCLONE ACROSS
THE SOUTHERN UNITED STATES WILL LIFT TO THE NORTHEAST TODAY AND
TONIGHT. AT THE SAME TIME...THE SUBTROPICAL JET WILL SLIDE NORTH AND
EAST...MARKING THE NORTHERN GULF COAST AND DEMARCATING THE SOUTHERN
EXTENT OF A BROAD UPPER LEVEL LOW. AS THESE FEATURES
PROGRESS...CYCLONIC AND CONFLUENT LOW LEVEL FLOW WILL BRUSH THROUGH
THE NORTHERN HALF OF THE GULF OF MEXICO...WELL REMOVED FROM THE
FLORIDA KEYS. THUS...SOUTHERLY STEERING FLOW TODAY WILL BECOME
SOUTHWESTERLY BY TUESDAY. SURFACE WINDS WILL DECREASE AS THE SURFACE
GRADIENT WEAKENS. THE PRODUCTS OF MESOSCALE PROCESSES ALONG OUR
ISLAND CHAIN AND ACROSS CUBA WILL CONTEND WILL INHIBITION AND DRY AIR
IN THE LOWER LEVELS. WE ADVERTISE A SLIGHT CHANCE OF SHOWERS THROUGH
MONDAY NIGHT GIVEN THE CHALLENGES. TUESDAY LOOKS PRETTY GOOD FOR A
REVERSE CLOUD LINE AND A CHANCE OF SHOWERS. TEMPERATURES WILL CLIMB
INTO THE UPPER 80S EACH AFTERNOON...IN FACT...KMTH WILL LIKELY REACH
90 FOR THE FIRST TIME THIS YEAR ON MONDAY.

&&

.LONG TERM (TUESDAY NIGHT THROUGH SATURDAY)...ZONAL MID- UPPER
LEVEL FLOW WILL STRETCH FROM THE EASTERN PACIFIC TO EAST OF THE
BAHAMAS. AS A MATTER OF DEFAULT...A WEAK HIGH PRESSURE SYSTEM WILL
DEVELOP ACROSS THE WESTERN ATLANTIC. MESOSCALE PRECIPITATION PROCESSES
WILL CONTINUE TO CONTEND WITH A NEARLY STATIONARY LOW LEVEL
ANTICYCLONIC CENTER OVER CUBA. A SECOND ROUND OF REVERSE CLOUD LINE
SHOWERS IS POSSIBLE ON WEDNESDAY...FOLLOWED BY STEERING FLOWS
FAVORABLE FOR MAINLAND CONVECTION TO COLLAPSE TOWARDS THE UPPER KEYS
ON THURSDAY AND FRIDAY. NO CHANGES WERE MADE TO THE LONG TERM
FORECAST WHICH SLOWLY TRAILS OFF RAIN CHANCES.

&&

.MARINE...MODERATE BREEZES WILL BECOME LIGHT TO GENTLE THIS
AFTERNOON. AS WINDS DECREASE...CHOOSING WIND DIRECTIONS BECOMES
CHALLENGING. SOME PERIODS HAVE BEEN ADVERTISED AS VARIABLE DUE TO
LOW CONFIDENCE IN THE PREVAILING WIND DIRECTION. FROM SYNOPSIS...A
RIDGE OF HIGH PRESSURE WILL EXTEND ACROSS THE SOUTHERN FLORIDA
PENINSULA TODAY THROUGH MONDAY. A TROUGH OF LOW PRESSURE WILL STALL
OVER SOUTH FLORIDA MONDAY NIGHT AND TUESDAY...AND WILL DISSIPATE
TUESDAY NIGHT. A RIDGE OF HIGH PRESSURE WILL REBUILD ACROSS CENTRAL
FLORIDA WEDNESDAY AND WEDNESDAY NIGHT...THEN SHIFT SOUTHWARD THURSDAY
AND THURSDAY NIGHT.

&&

.AVIATION...VFR CONDITIONS ARE EXPECTED AT THE ISLAND TERMINALS
TODAY. SURFACE WINDS WILL BE 5 TO 10 KNOTS...GENERALLY OUT OF THE
SOUTHEAST...BUT WITH MORE THAN USUAL VARIABILITY.

&&

.PRELIMINARY POINT TEMPS/POPS...
KEY WEST  85  78  85  77 / 10 20 20 20
MARATHON  89  79  90  78 / 10 20 20 20

&&

.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&

$$

PUBLIC/MARINE.........CLR
AVIATION/NOWCASTS.....11
DATA COLLECTION.......CHESSER

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