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NATIONAL METEOROLOGICAL SERVICE OF BELIZE

FORECAST DISCUSSION

DATE: MONDAY 29TH SEPTEMBER 2014 (EVENING)  

SAT IMAGERY AND RADAR OBS SHOWED THAT EXCEPT FOR ISOLATED THUNDERSTORMS OVER THE MAYA MOUNTAINS.... THE WX WAS MAINLY FAIR, WARM AND MOSTLY DRY THIS AFTERNOON AND EVENING. WV IMAGERY DETECTED MOSTLY DRY CONDITIONS AT MID-UPPER LVLS OVER THE NW'RN CARIBBEAN - YUCATAN AND BZE WHILE MOISTURE INCREASED EAST OF 83W IN RESPONSE TO A DEVELOPING LOW. LATEST MIMIC-PW IMAGE SHOW AVILABLE MOISTURE IN THE RANGE OF 40-50mm NEAR AND OFFSHORE BZE. SKEW-T (30 / 00Z) SOUNDING SHOWED A DRY AND MARGINALLY STABLE ENVIRON WITH PW 46.63mm, KI 28.90, LIFTED -4.20, SHOW 1.62 AND CAPE 2720j/kg. 

SFC ANALYSIS (TPC - 29 /18Z) HAD A RELATIVELY SLACK PRESSURE GRADIENT OVER THE GLFMEX - CENTRAL AMERICA AND THE W'RN CARIBBEAN SUPPORTING A LIGHT E'LY - ESE'LY FLOW OVER OUR AREA. A SEAMINGLY INACTIVE TROPICAL WAVE WAS ANALYZED OVER THE W'RN CARIBBEAN ALONG 83W SOUTH OF 22N. AT LOW LVLS (850-700hPa) THE FLOW WAS ESE'LY - SE'LY AS A RIDGE EXTENDED INTO THE E'RN GLFMEX. AT MID LVLS 500hPa THE FLOW CONTINUED ESE'LY AS THE RIDGE CENTERED ON A HIGH OVER S'RN FLORIDA / W'RN CUBA. AT THE UPPER LVLS (300-200hPa) THE FLOW BECMGS NE'LY AS THE MAIN FEATURES ARE A RIDGE OF HIGH PRESSURE EXTENDING E'WARD ACROSS MEXICO AND THE GLF AND A TROUGH EXTENDING SW'WARDS ACROSS THE ISLAND OF HISPANIOLA TO HONDURAS / NICARAGUA. THE PATTERN SUPPORTS A CONFLUENT / CONVERGENT / SUBSIDENT FLOW ALOFT.

THE GFS (12Z / 18Z) MODEL RUNS FCST A DIURNAL VARIATION OF THE SFC FLOW FROM E'LY- ESE'LY DURING THE NEXT FEW DAYS. THE SLACK PRESSURE GRADIENT / LIGHT WINDS IS TO CONTINUE OVER THE AREA. IN A WEAKLY CONVERGENT PATTERN.... LOW LVL MOISTURE IS FCST TO CONFINE BELOW 800-750hPa THROUGH EARLY WED THEN SOME INCREASE IN MOISTURE OCCURS AT MID LVLS. BY EXTRAPOLATION THE TROPICAL WAVE IS FCST TO CROSS THE COUNTRY TOMORROW BUT SHOWS LITTLE OR NO SIGNATURE IN THE WIND FIELD. AT UPPER LVLS THE RIDGE IS TO PERSIST TO THE NORTH AND NORTHWEST AS THE TROUGH AXIS DRAWS NW'WARDS TO ACROSS HONDURAS TO NEAR S'RN BZE TOMORROW THEN WEAKENS AS IT DRIFTS BACK TO THE SOUTH. THE CONVERGENT / SUBSIDENT PATTERN IS TO PERSIST THROUGH THROUGH TOMORROW NIGHT THEN WEAK DIVERGENCE DEVELOPS AT MID AND UPPER LVLS. THE SYNOPTIC PATTERN SUGGEST SHOWERS SHOULD CONTINUE GENERALLY ISOLATED DURING THE FCST AND EXTND PERIODS WITH A SLIGHT INCREASE DURING DAY THREE. HOWEVER DAYTIME / DIURNAL HEATING AND / OR TOPOGRAPHICAL FORCING IS LILELY TO SUPPORT ISOL MOD CONVECTION DURING THIS TIME FRAME.   

THE GFS FCST MOSTLY LIGHT RR AMTS OF .10-.25ins/6hrs EXCEPT FOR LOCALIZED MAX OF 0.5ins/6hrs OVER THE SOUTH AND WEST. THE NAM IS EVEN MORE CONSERVATIVE BUT ALSO GOES FOR ISOL AFTERNOON MAX .50ins/6hrs OVER INLAND AREAS. LIKE THE NAM THE NVG IS ALSO LESS ACTIVE BUT WITH A SMALLER MAX 8mm/6hrs EARLY MORNING OVER THE NORTH. 

FORECAST:  PARTLY CLOUDY TONIGHT AND MOSTLY SUNNY TOMORROW. SHOWERS WILL BE ISOLATED ALONG WITH ISOLATED THUNDERSTORMS OVER THE SOUTH TONIGHT AND INLAND TOMORROW AFTERNOON. 

OUTLOOK: FOR TUES. NIGHT AND WED. IS FOR SIMILAR WEATHER CONDITIONS TO PREVAIL. 

MARINE:  WINDS: E-SE 5-15 KTS.; SEAS: LIGHT CHOP-CHOPPY.; WAVES:2-4 FT. 

FORECASTER:    M.  GENTLE.