Subject: Western Pacific: Synoptic Discussion For The Marianas

From: LDM Weather <[email-masked]>
Date: Mon, 04 Feb 2008 13:35:07 -0600

286 
FXPQ60 PGUM 041934
AFDPQ 

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
534 AM CHST TUE FEB 5 2008

.SYNOPSIS...
200 MB INITIAL GFS WIND FIELDS AND ANIMATED WATER VAPOR IMAGERY SHOW 
A TUTT ENCROACHING FROM THE WEST. THIS APPEARS TO EXPLAIN RECENT 
ENHANCEMENT AND FORMATION OF TRADE-WIND DISTURBANCES NEAR AND EAST 
OF THE MARIANAS. ONE OF THESE IS PASSING THROUGH NOW...WITH THE NEXT 
ONE FOLLOWING CLOSELY BEHIND. AWIPS DISTANCE SPEED TOOL INDICATES 
THE NEXT DISTURBANCE IS DUE TO ARRIVE AROUND DAWN AND COULD LAST 
MUCH OF TODAY. AT PRESENT...LOOKS LIKE TINIAN AND SAIPAN WILL
RECEIVE THE SCATTERED SHOWERS FROM THIS SYSTEM. ACCORDINGLY...HAVE
SPLIT THE ZFP/CWF TO REFLECT THIS DICHOTOMY.

&&

.DISCUSSION...
CLOUD/SHOWER ENHANCEMENT TREND EAST OF THE MARIANAS CONTINUES. 
THIS...AND GFS TIME/HEIGHT CROSS SECTION...SUGGESTS MOSTLY CLOUDY 
SKIES WILL PREVAIL OVER TINIAN AND SAIPAN THROUGH TONIGHT. WITH MORE 
MOISTURE/RAINFALL IN PLACE...HAVE MADE ADJUSTMENTS TO MAX/MIN 
TEMPERATURES AS WARRANTED. 

NO CHANGES TO PREVIOUS LINE OF THINKING. STRENGTH OF RIDGE TO NORTH 
WILL MODULATE TRADE-WIND SPEED. A SQUEEZE PLAY IS SETTING UP BETWEEN 
TRADE-WIND DISTURBANCE TO THE SOUTH AND STRONG HIGH PRESSURE TO THE 
NORTH FRI AND SAT. WILL LEAN TOWARD THE HIGH SIDE OF GUIDANCE FOR 
WIND SPEEDS HERE. MODELS STILL CONSISTENT IN KEEPING CLOUDS/QPF 
WITH THIS SYSTEM WELL SOUTH OF GUAM...SO WILL NOT BITE ON THIS ONE YET 
AND LEAVE DRY SEASON CLIMO GRIDS IN PLACE FOR THE LONG TERM.

&&

.EASTERN MICRONESIA...
DIVERGENCE ALOFT IS ENHANCING CONVECTION IN THE AREA MAINLY SOUTH
AND WEST OF POHNPEI AND KOSRAE. A THUNDERSTORM OR TWO MAY BE
POSSIBLE IN THE VICINITY OF POHNPEI. SHOWERS OVER KOSRAE HAVE
EASED A BIT BUT WILL RESUME ON WEDNESDAY. ANOTHER AREA OF TRADE
CONVERGENCE IS MOVING INTO SOUTHERN MARSHALL ISLANDS AND WILL
PROVIDE MORE RAIN FOR BOTH ISLANDS WEDNESDAY INTO FRIDAY. MAJURO
HOWEVER SHOULD BE ABLE TO AVOID THE HEAVY SHOWERS AND REMAIN
NORTH OF THIS AREA.

WIND WAVES CONTINUE TO GENERATE HIGH SURF FOR POHNPEI...KOSRAE AND 
MAJURO THRU AT LEAST WEDNESDAY. 

&&

.WESTERN MICRONESIA...
DIVERGENCE ALOFT CONTINUES TO ENHANCE THE CONVECTION ASSOCIATED WITH 
TRADE WIND CONVERGENCE SOUTH OF KOROR AND YAP.  MUCH OF THE HEAVY 
CONVECTION WILL STAY SOUTH OF THE ISLANDS. THEREFORE...KEPT ONLY
A FEW SHOWERS IN THE KOROR FORECAST TODAY. MODELS POINT TO THE
DISTURBANCE SOUTHWEST OF CHUUK BRINGING INCREASED CLOUDINESS AND
SHOWERS TO BOTH YAP AND KOROR BY FRIDAY. CURRENTLY A LARGE AREA OF
SHOWERS LOCATED SOUTH OF CHUUK REMAINS CONSISTENTLY SOUTH OF
LATITUDE 6N. THIS AREA IS STILL CLOSE ENOUGH TO CHUUK THAT
OCCASIONAL HEAVY SHOWERS ARE A POSSIBILITY DURING THE NEXT TWO
DAYS. SKEW-T PROFILE INDICATES A THUNDERSTORM POTENTIAL FOR THE
ISLAND.

&&

.MARINE...
INHERITED SWELL GRIDS LOOKS GOOD. NO HIGH SURF ADVISORIES ARE 
FORESEEN. A SMALL CRAFT ADVISORY IS POSSIBLE TONIGHT AS A TRADE-WIND 
SURGE ARRIVES. HAVE NOT ADDED THIS TO THE HAZARD GRIDS BUT HAVE MADE 
MENTION OF THIS IN THE CWF SYNOPSIS.

&&

.FIRE WEATHER...
WHAT A DIFFERENCE A DAY MAKES... TUTT HAS BACK DOORED THE MARIANAS 
WITH ENOUGH DYNAMIX TO CAUSE SIGNIFICANT ENHANCEMENT/DEVELOPMENT OF 
TRADE-WIND DISTURBANCES JUST BEFORE THEY MOVE THROUGH THE MARIANAS. 
MODEL GUIDANCE WAS WAY UNDERDONE WITH RESPECT TO QPF RECEIVED AT THE 
AIRPORT RAIN GAUGE YESTERDAY. 56 HUNDREDTHS OF AN INCH FELL...WELL 
ABOVE THE WETTING RAIN THRESHOLD. BASED UPON THIS...WILL CANCEL THE 
FIRE WEATHER WATCH CURRENTLY IN EFFECT. 

TUTT SHOULD MOVE OUT AS TRADE WINDS PICK UP TOWARD THE MIDDLE OF THE 
WEEK. THUS EXPECT RAINS JUST RECEIVED WILL CONSTITUTE TEMPORARY 
RELIEF. AT THIS POINT...DO NOT FORESEE A FIRE WEATHER WATCH DURING 
THE NEXT FEW DAYS. WILL HAVE TO SEE HOW MUCH DRYING TAKES PLACE AS 
THE WEEK ADVANCES.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...NONE.
MARIANAS WATERS...NONE.
&&

$$

MCELROY/MILLER

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