From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Thu Sep 16 05:20:48 2010 Received: from vacuum.cso.uiuc.edu (vacuum.cso.uiuc.edu [128.174.5.113]) by cozumel.ust.hk (8.13.8/8.13.8) with ESMTP id o8FLKliT000628 for ; Thu, 16 Sep 2010 05:20:48 +0800 Received: from vacuum.cso.uiuc.edu (vacuum.cso.uiuc.edu [128.174.5.113]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o8FKbVtM000579; Wed, 15 Sep 2010 16:20:00 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3412472 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Wed, 15 Sep 2010 16:20:00 -0500 Received: from relay07.cites.uiuc.edu (relay07.cites.uiuc.edu [128.174.4.73]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o8FLK0YN009672 for ; Wed, 15 Sep 2010 16:20:00 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay07.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o8FLJr1Q008920 for ; Wed, 15 Sep 2010 16:19:59 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 58A5A405001E; Wed, 15 Sep 2010 16:19:53 -0500 (CDT) X-Spam-Score: 0 X-Spam-Details: rule=no-quarantine_notspam policy=no-quarantine score=0 spamscore=0 ipscore=0 phishscore=0 bulkscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx engine=5.0.0-1005130000 definitions=main-1009150116 X-Spam-OrigSender: ldm@weather3.admin.niu.edu X-Spam-Bar: Message-ID: <20100915211953.58A5A405001E@weather3.admin.niu.edu> Date: Wed, 15 Sep 2010 16:19:53 -0500 Reply-To: wxmaster@COX.NET Sender: WX-TROPL Tropical Storm and Hurricane WX products From: LDM Weather Subject: Western Pacific: Synoptic Discussion For The Marianas To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list 185 FXPQ60 PGUM 152119 AFDPQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TIYAN GU 719 AM CHST THU SEP 16 2010 .SYNOPSIS... PGUA WSR-88D SHOWS ISOLATED SHOWERS AND THUNDERSTORMS MOVING THROUGH THE MARIANAS WATERS. THESE ARE ASSOCIATED WITH A BROAD AREA OF ACTIVITY BEING CAUSED BY AN UPPER-LEVEL LOW EXTENDING FROM 10N TO 25N FROM 139E TO 170E. FARTHER SOUTH TRADE-WIND CONVERGENCE IS CREATING SCATTERED SHOWERS THROUGHOUT MICRONESIA...EXCEPT THEY ARE A LITTLE SOUTH OF YAP. && .DISCUSSION... UPPER-LEVEL LOW MOVING THROUGH ALREADY TRIGGERED SOME THUNDER EARLY THIS MORNING. MORE COULD ERUPT ANY TIME. FOR THE MOST PART THE LOW ACTIVITY PORTION OF THE LOW SHOULD PASS OVER US...SO KEPT THE ACTIVITY ISOLATED AT THIS TIME. GUAM MAY WELL HAVE SOME ISLAND THUNDER TODAY...BUT WE COULD END UP HARD PRESSED TO TELL IT APART FROM THE STUFF ASSOCIATED WITH THE TROPICAL UPPER TROPOSPHERIC TROUGH /TUTT/. THEREFORE DID NOT MAKE ANY SPECIAL MENTION OR ZONE SPLITS IN THE FORECASTS. && .MARINE... REDUCED EAST SWELL TO 2 FEET THE NEXT COUPLE OF PERIODS IN RESPONSE TO UPDATED WAVE GUIDANCE AND THE IPAN BUOY. BENIGN CONDITIONS WILL CONTINUE AS EVEN WHEN THE SWELLS RISE LATER IN THE PERIOD...THEY SHOULD ONLY GET UP TO ABOUT 4 FEET. && .EASTERN MICRONESIA... THE SOUTHWESTERN END OF THE SUB-TROPICAL RIDGE IS PERSISTING OVER THE PHILIPPINE SEA JUST NORTH OF WESTERN MICRONESIA. THIS FEATURE IS CREATING A BLOCKAGE AGAINST THE TRADE-WIND FLOW OVER EASTERN MICRONESIA. IN RESPONSE...SURFACE IMPULSES ARE FORMING ALONG THE TRADE CONVERGENCE ZONE FROM CHUUK STATE EASTWARD TO THE DATE LINE. EXPECT PERIODS OF SHOWERS AND ISOLATED THUNDERSTORMS FOR CHUUK AND POHNPEI INTO THE WEEKEND...AND FOR KOSRAE AND MAJURO THRU TONIGHT. THEN A DRIER SOUTHEASTERLY TRADE SURGE WILL PROMOTE A BRIEF MOMENT OF FAIRER WEATHER FOR BOTH MAJURO AND KOSRAE FRIDAY AND SATURDAY. WITH THE SUB-TROPICAL RIDGE WEAKENING BY EARLY NEXT WEEK...GENTLE TO MODERATE TRADES SHOULD RETURN TO THE REGION FROM EAST TO WEST. HOWEVER...AN UPPER-LEVEL TROUGH DIGGING SOUTHWESTWARD FROM EAST OF WAKE ISLAND CAN ENHANCE TRADE-WIND SHOWER ACTIVITY FOR MAJURO AND KOSRAE. THIS SCENARIO WILL ALSO PROLONG SHOWERY CONDITIONS FOR POHNPEI AND CHUUK AS WELL. && .WESTERN MICRONESIA... AN AREA OF SURFACE CONVERGENCE BETWEEN TRADE WINDS AND THE AFOREMENTIONED SUB-TROPICAL RIDGE IS CLEARLY VISIBLE ON BOTH ASCAT AND IR SATELLITE IMAGERY THIS MORNING. THE LEADING EDGE OF THIS AREA IS APPROACHING KOROR AND WILL SPREAD SCATTERED CONVECTION OVER THE ISLAND BY NOON TODAY. WITH THE CONVERGENCE ZONE EXTENDING NORTHEASTWARD FROM KOROR PASSING SOUTH OF YAP...ONLY ISOLATED SHOWERS ARE ANTICIPATED FOR YAP TODAY. AS A SURFACE TROUGH DEPARTS FROM CHUUK AND DRIFTS WESTWARD LATER TONIGHT...IT WILL CAUSE THE CONVERGENCE ZONE TO SHIFT NORTHWARD OVER YAP. TEAMING UP WITH AN UPPER TROUGH MOVING THROUGH THE AREA...SPORADIC CONVECTION WILL CONTINUE FOR BOTH LOCATIONS THRU FRIDAY. LATEST WV IMAGERY REVEALS AN AREA OF MUCH DRIER AIR TRAILING BEHIND THE SURFACE TROUGH SOUTHWEST OF CHUUK. THIS ELEMENT CAN BRIEFLY DECREASE SHOWER COVERAGE OVER THE WEEKEND BUT WET PATTERN WILL LIKELY RETURN BY NEXT WEEK AS MORE DISTURBANCES ARE PRESENT UPSTREAM. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...NONE. MARIANAS WATERS...NONE. && $$ STANKO/CHAN +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ To unsubscribe from WX-TROPL send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with "unsub wx-tropl" in the body of your message. For help with WX-TROPL write to cnovy@cox.net. For more information on tropical weather products, see the NHC Homepage at http://www.nhc.noaa.gov.