San Juan Discussion
Posted by
JAC on 8/31/2009, 7:31 am
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JUAN PR 430 AM AST MON AUG 31 2009
.SYNOPSIS...TUTT LOW NORTH OF PR WILL DRIFT TO THE WEST SOUTHWEST AND SETTLE OVR HISPANIOLA BY TONIGHT. UPPER LVL RIDGE OVR THE TROP ATLC WILL BUILD WWD INTO THE ERN CARIBBEAN TUE THROUGH WED AND MAINTAIN A SUBSIDENT PATTERN ACROSS THE REGION. MEANWHILE...BROAD AREA OF LOW PRES ALONG 50W THIS MORNING WILL TRACK SLOWLY TO THE WNW OVER THE NEXT SVRL DAYS AND MOVE ACROSS THE REGIONAL WATERS THU NIGHT.
&&
.DISCUSSION...MODELS SHOW TUTT LOW DRIFTING TO WEST SOUTHWEST WITH SUBSIDENCE INCREASING TOWARD THE END OF THE DAY. HAVE TRENDED POPS DOWNWARD FOR TODAY BUT STILL ANTICIPATING ISOLD/SCT STRONG CONVECTION OVR WRN PR THIS AFTERNOON. SUBSIDENCE/DRYING INCREASES ON TUE AND HOLDS THROUGH WED AS MID-UPPER LVL RIDGING BUILDS FROM THE EAST FURTHER LIMITING PRECIP CHANCES. SFC WINDS TURN MORE TO THE NORTHEAST SO HAVE LIMIT POPS TO THE SOUTHWEST CORNER OF PR.
FORECAST FOR THU THROUGH FRI IS HIGHLY DEPENDENT ON TRACK/EVOLUTION ON BROAD AREA OF LOW PRES ALONG 50W THIS MORNING. HAVE FOLLOWED THE 00Z ECMWF CLOSELY DURING THIS TIME FRAME AS IT HAS BEEN THE MOST CONSISTENT/RELIABLE MODEL THIS YEAR AND ALSO WITH THIS SYSTEM TAKING IT ACROSS THE WATERS JUST NORTH OF PR/USVI OVER THE PAST FOUR DAYS AS A WEAK TROPICAL CYCLONE. NOGAPS AND CANADIAN MODELS ALSO DEVELOP THIS SYSTEM WHILE GFS/UKMET DO NOT. PER NHC TWO PRODUCT...CONDITIONS STILL APPEAR FAVORABLE FOR FURTHER DEVELOPMENT. IN ADDITION...THE FIRST FEW SATELLITE IMAGES AFTER THE ECLIPSE SHOW THUNDERSTORMS BECOMING MORE CONCENTRATED NEAR THE CENTER. GIVEN THAT WE ARE ALMOST AT THE PEAK OF THE HURRICANE SEASON AND AT LEAST MARGINALLY FVRBL CONDITIONS I WOULD EXPECT AT LEAST A NAMED STORM AND NHC IS GIVING IT A HIGH CHANCE OF DEVELOPING INTO A TROPICAL CYCLONE. PLEASE REFER TO NHC PRODUCTS FOR MORE DETAILS ON THIS SYSTEM.
THERE IS A GREAT DEAL UNCERTAINTY HERE ESPECIALLY WITH RESPECT TO TIMING AND INTENSITY ALTHOUGH NOT AS EXTREME AS YESTERDAY. THE EARLY TRACK NHC MODELS SHOW THE SYSTEM ONLY TO ABOUT 61W BY FRI EVENING WHILE THE 00Z ECWMF SHOWS THE SYSTEM ALMOST TO 70W BY THIS TIME. THE ECMWF LOOKS MORE REASONABLE WHEN COMPARED TO CLIMATOLOGY AS A SYSTEM THAT IS ALREADY AT 50W WOULD ONLY TAKE ON AVERAGE A MAXIMUM OF FOUR DAYS TO GET TO THE LONGITUDE OF PR MOVING AT THE CLIMO RATE OF SPEED OF 10 KNOTS BUT EVEN THE ECMWF SHOWS THE SYSTEM SLOWING DOWN TOO WHEN IT REACHES 55W. HAVE ADJUSTED GRIDS THU-FRI TO ADD MORE WX/POPS AND INCREASE WINDS AND SEAS.
&&
|
70
In this thread:
Another DMAX Flare for 94L -
JAC,
8/31/2009, 6:40 am- Gettin Warmer - JAC, 8/31/2009, 11:34 am
- Still a wave on QSCAT - JAC, 8/31/2009, 8:05 am
- What shear? - JAC, 8/31/2009, 8:01 am
- 50 to 55K-ft Cloud Tops - JAC, 8/31/2009, 7:53 am
- Models all over the place on how the East-Coast High builds - JAC, 8/31/2009, 7:49 am
- TPC's forecast 48 & 72 hrs out - JAC, 8/31/2009, 7:35 am
- San Juan Discussion - JAC, 8/31/2009, 7:31 am
- A lot of uncertainty in GFS Ensembles - JAC, 8/31/2009, 7:17 am
- Pressure at closest buoy = 1007mb - JAC, 8/31/2009, 7:08 am
- Anti-cyclone - JAC, 8/31/2009, 6:58 am
- LLC not closed off at surface yet - JAC, 8/31/2009, 6:48 am
- Great looking cu-nims on VIS - JAC, 8/31/2009, 6:45 am
Post A Reply
This thread has been archived and can no longer receive replies.