FXUS62 KMLB 261004
AFDMLB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
504 AM EST SAT DEC 26 2009
.DISCUSSION...
CURRENT-TODAY...A COLD FRONT CONTINUES TO PUSH AWAY FROM THE EAST
COAST INTO THE WESTERN ATLC EARLY THIS MORNING. A HIGH LEVEL
BROKEN- OVERCAST CLOUD DECK IN PLACE OVER EAST CENTRAL FLORIDA AND
WILL LIKELY BE AROUND FOR MUCH OF THE DAY WITH INFLUENCE FROM THE
RIGHT REAR QUAD OF THE UPPER JET OVERHEAD. FOR SKY CONDITIONS WILL
USE VERBIAGE...SUNSHINE OCCASIONALLY FILTERED THROUGH HIGH
CLOUDINESS. NORTHWEST WINDS ARE LIGHT AND SHOULD REMAIN BETWEEN 5
AND 10 MPH FOR THIS PERIOD. AT THE SURFACE DRIER AND COOLER AIR
CONTINUE TO FILTER IN BEHIND THE PREVIOUS DAY'S BOUNDARY WITH
DEWPOINT READINGS IN THE UPPER 40S TO MIDDLE 50S AND FORECAST TO
FALL INTO THE UPPER 30S TO MIDDLE 40S FOR A LARGE AREA ACROSS THE
CENTRAL INTERIOR...NORTH & WEST OF BREVARD COUNTY. HIGH PRESSURE
ALONG THE GULF COAST STATES WILL CONTINUE TO SLIDE EASTWARD
THROUGH THE DAY TOWARD THE SOUTHEAST U.S. HIGHS WILL BE MUCH
COOLER AND BELOW CLIMO WITH MAX TEMPERATURES MAINLY IN THE 60S
WITH A FEW READINGS NEAR 70 DEGREES TO LOW 70S SOUTHWARD ALONG THE
COAST FROM KMLB AND POSSIBLY INTO SOUTHERN OSCEOLA AND OKEECHOBEE
COUNTIES. WILL KEEP CONDITIONS DRY IN THE WEATHER GRIDS.
TONIGHT...LATEST MODEL SOUNDINGS CONTINUE TO SUGGEST A GRADUAL
MOISTENING FROM TOP TO BOTTOM WITH THE DEVELOPMENT & APPROACH OF
THE NEXT WEATHER SYSTEM OVER THE WESTERN GULF. DRIER AIR WILL
STILL REMAIN IN PLACE NEARER THE SURFACE WITH DEWPOINTS FORECAST
FROM THE UPPER 30S NORTHWEST INTERIOR...40S JUST ABOUT EVERYWHERE
ELSE EXCEPT A FEW LOWER 50S NEAR THE TREASURE COAST. WILL GO AHEAD
AND YANK SCHC POPS OUT OF THE FCST AS FEEL THE LOWER ATMOSPHERE
WILL BE TOO DRY FOR ANYTHING MORE THAN VIRGA...AND THAT WOULD
LIKELY BE LATE OVERNIGHT. LOWS WILL RANGE FROM THE LOWER 40S
ACROSS THE NORTHWEST INTERIOR TO LOWER 50S FURTHER SOUTH ALONG THE
TREASURE COAST. WIND SPEEDS SHOULD FALL BELOW 5 MPH THIS EVENING
THROUGH THE OVERNIGHT.
SUN...FORECAST SOUNDINGS SHOW DRY AIR MASS MOISTENING FROM THE
TOP DOWN AS WEAK MID LEVEL DISTURBANCE IN FAST UPPER FLOW
APPROACHES FROM THE GULF OF MEXICO. THE RESULT WILL BE A LOWERING
AND THICKENING OF THE CLOUD BASE PRODUCING A MOSTLY CLOUDY TO
OVERCAST DAY. SOUNDINGS SHOW SIGNIFICANT DRY AIR IN THE LOW LEVELS
(850-925MB) WILL BE THE LAST TO ERODE...AT LEAST PARTIALLY FROM
LIGHT PRECIPITATION FALLING INTO THE DRY LAYER. RAIN CHANCES ARE
TRICKY AS ANY PRECIP WILL BE LIGHT AND MAY INITIALLY EVAPORATE
BEFORE REACHING THE GROUND (VIRGA). GFS IS INDICATING THE BEST
ISENTROPIC LIFT WILL BE ACROSS NORTH HALF BUT THIS IS ALSO WHERE
THE DRIER AIR WILL RESIDE. SO IT MAY BE DIFFICULT TO ACHIEVE
MEASURABLE PRECIP AT MANY LOCATIONS.
BUT HAVE HIGHER CONFIDENCE THAT LITTLE OR NO SUNSHINE AND A NORTH
WIND WILL MAKE IT A CHILLY DAY. MAX TEMPS MAY STRUGGLE TO GET OUT
OF THE 50S NORTH OF ORLANDO...AND MIGHT BE LUCKY TO REACH 70
AROUND LAKE OKEECHOBEE.
MON-THU...HIGH PRESSURE OVER THE PLAINS WILL BUILD EASTWARD INTO
FL AND REINFORCE THE COOL DRY AIRMASS MONDAY AND TUE. TUE LOOKS
LIKE THE COLDEST MORNING WITH UPPER 30S NORTH OF ORLANDO AND MAX
TEMPS NOT GETTING OUT OF THE 60S AREAWIDE DESPITE FULL SUNSHINE.
FREEZING TEMPS NOT EXPECTED AT THIS TIME. THE HIGH PRESSURE WILL
BE QUITE PROGRESSIVE...SHIFTING QUICKLY EAST TO THE MID ATLC COAST
BY WED MORNING. VEERING WINDS TO THE EAST AND SOUTHEAST WED WILL
BEGIN A QUICK WARMING AND MOISTENING TREND AS RETURN FLOW SETS UP
AHEAD OF THE NEXT WEATHER SYSTEM TAKING SHAPE IN THE WESTERN GULF
OF MEXICO.
HAVE HIGH CONFIDENCE MON-WED WILL BE RAIN-FREE. THEN SIGNIFICANT
DIFFERENCES IN GFS/ECMWF REDUCE CONFIDENCE IN THU-FRI FORECAST.
00Z GFS BRINGS THE NEXT FRONT THROUGH IN 2 PHASES WITH FASTER
WEAKER SFC LOWS AND UNSETTLED CONDITIONS WED NIGHT THRU FRI
MORNING. ECMWF IS STRONGER WITH THE SFC LOW BUT SLOWER...BRINGING
A SQUALL LINE ACROSS CENTRAL FLORIDA THU NIGHT. HAVE KEPT
SCATTERED SHOWERS/ISOLATED STORMS THURSDAY...THU NIGHT AND FRIDAY
DUE TO UNCERTAINTY REGARDING TIMING AND INTENSITY. EVENTUALLY
MODEL GUIDANCE SHOULD COME INTO BETTER AGREEMENT AND CONSISTENCY
AND WE WILL BE ABLE TO NARROW THE WINDOW OF INCLEMENT WEATHER. RAIN
CHANCES WILL LIKELY INCREASE FOR SOME PORTION OF NEW YEARS EVE/NEW
YEARS DAY.
&&
.AVIATION...
BKN TO OCNL OVC HIGH CLOUD DECK ABV FL150 TO CONTINUE THRU THE
DAY AND INTO TONIGHT. EARLY MORNING ENCROACHMENT FROM THE WEST OF
A BKN-OVC 025-030 DECK NR KLEE. WILL MONITOR AND UPDATE TAFS IF
THIS TREND WERE TO CONTINUE FURTHER EASTWARD. OTHERWISE...EXPECT
PREVAILING VFR CONDITIONS TO RULE.
&&
.MARINE...
TODAY-TONIGHT...NORTHWEST WINDS WILL AVERAGE NEAR 15 KTS OFFSHORE
WITH 10-15 KTS NEAR SHORE. SEAS ARE FCST MAINLY 2-4 FT NEAR SHORE
WITH 5-7 FT OFFSHORE THRU LATE AFTN. THE SCA FOR SEAS WILL EXPIRE
AT 21Z (4PM). CAUTIONARY CONDITIONS FOR SEAS AWAY FROM THE COAST
WILL STILL BE NECESSARY FROM LATE THIS AFTN THRU THE NIGHT.
SUN...NORTH FLOW WILL PERSIST AS HIGH PRESSURE RIDGE EXTENDS ACROSS
NORTH FLORIDA. RIGHT NOW THE PRESSURE GRADIENT LOOKS LIKE IT WILL
SUPPORT 10-15 KNOTS. THIS SHOULD PRODUCE A CHOPPY WIND WAVE
ESPECIALLY IN THE GULF STREAM. IN ADDITION...NOAA WAVEWATCH IS
SHOWING A MODERATE (4 FT) LONG PERIOD (~12SEC) NE SWELL WHICH
SHOULD PRODUCE HAZARDOUS CONDITIONS NEAR INLETS.
MON-WED...A REINFORCING COLD FRONT IS FORECAST TO CROSS THE WATERS
EARLY MON INCREASING THE NORTHWEST FLOW AND HAZARDOUS BOATING
CONDITIONS. SMALL CRAFT ADVISORIES ARE PROBABLE AT LEAST FOR THE
OFFSHORE WATERS MON-TUE. HIGH PRESSURE WILL BE PROGRESSIVE AND
THE WINDS WILL VEER QUICKLY TO THE SOUTHEAST ON WED AS LOW
PRESSURE ADVANCES EASTWARD ALG THE GULF COAST. BASED ON SPEED AND
STRENGTH OF THE LOW...PRESSURE GRADIENT SHOULD NOT SUPPORT MORE
THAN 15 KNOTS WED AFTN. A MODERATE LONG PERIOD ENE SWELL WILL
CONTINUE TO PRODUCE HAZARDOUS CONDITIONS IN THE SURF ZONE AND
NEAR INLETS THIS PERIOD.
&&
.FIRE WEATHER...
DRIER AIR WILL FILTER DOWN THE PENINSULA IN LIEU OF THE LATEST
COLD FRONT TODAY. ONE TO THREE HOURS OF RH VALUES FROM 35%-40%
WILL BE POSSIBLE OVER OUR NORTHWEST INTERIOR THIS AFTERNOON
(LAKE...SEMINOLE AND INLAND VOLUSIA COUNTIES). ELSEWHERE...RH
VALUES SHOULD REMAIN FURTHER ABOVE CRITICAL LEVELS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DAB 64 47 62 45 / 0 10 30 20
MCO 65 47 62 48 / 0 10 30 20
MLB 70 52 67 52 / 0 10 20 20
VRB 71 53 70 55 / 0 10 20 20
LEE 63 44 61 44 / 0 10 30 20
SFB 66 46 63 47 / 0 10 30 20
ORL 65 47 63 49 / 0 10 30 20
FPR 72 52 70 53 / 0 10 20 20
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM EST THIS
AFTERNOON FOR WATERS FROM FLAGLER BEACH TO JUPITER INLET 20
TO 60 NM OFFSHORE.
&&
$$
SHORT TERM...SEDLOCK
LONG TERM....KELLY
