From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Thu Sep 16 16:14:03 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 o8G8E2n1006335 for ; Thu, 16 Sep 2010 16:14:03 +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 o8G50Bcc023157; Thu, 16 Sep 2010 03:13:22 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3420604 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Thu, 16 Sep 2010 03:13:22 -0500 Received: from relay09.cites.uiuc.edu (relay09.cites.uiuc.edu [128.174.4.86]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o8G8DMCo005902 for ; Thu, 16 Sep 2010 03:13:22 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay09.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o8G8DFTA009699 for ; Thu, 16 Sep 2010 03:13:21 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 5ACA1405001E; Thu, 16 Sep 2010 03:13:15 -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-1009160005 X-Spam-OrigSender: ldm@weather3.admin.niu.edu X-Spam-Bar: Message-ID: <20100916081315.5ACA1405001E@weather3.admin.niu.edu> Date: Thu, 16 Sep 2010 03:13:15 -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 885 FXPQ60 PGUM 160813 AFDPQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TIYAN GU 613 PM CHST THU SEP 16 2010 .SYNOPSIS...LATEST SATELLITE AND RADAR SHOW THE MARIANAS... ESPECIALLY IN THE GUAM AND ROTA ZONES...ARE STILL UNDER THE INFLUENCE OF A SLOW MOVING UPPER TROUGH...NOW WEST OF THE ISLANDS. POSSIBILITY OF THUNDERSTORMS REMAINS FOR THE NEXT SEVERAL DAYS... AND THE ADDITION OF SCATTERED SHOWERS BY SUNDAY INTO MONDAY FOR A WEAK WESTERLY-MOVING DISTURBANCE CURRENTLY JUST EAST OF 150E. && .DISCUSSION...YET TO SEE HOW MUCH RAIN WE GET FROM THE WEAKLY DEFINED DISTURBANCE NOW LOCATED BETWEEN 150E AND 160E THAT WAS FORMERLY DESCRIBED BY JTWC AS 98W. EVIDENCE OF A CIRCULATION NO LONGER EXIST BUT MODELS ARE CONSISTENT WITH BRINGING SOMETHING IN ON SUNDAY. THE EXACT TIMING AND THE AMOUNT OF MOISTURE DEPENDS ON THE MODEL WITH THE ECMWF THE MOST AGGRESSIVE...AS ALWAYS. WATER VAPOR IMAGERY SHOWS PLENTY OF MOISTURE CONVERGENCE ALONG THE SOUTHERN AND EASTERN PERIPHERY OF THE UPPER TROUGH LEADING INTO THE DISTURBANCE THAT I THINK IT A GOOD BET FOR THE MARIANAS WATERS IN GENERAL AND GUAM... WITH ITS ISLAND HEATING...IN PARTICULAR TO HAVE A CHANCE OF THUNDERSTORMS EACH OF THE NEXT 3-4 DAYS. IF THE SCENARIO GOES AS PLANNED...WEATHER SHOULD GO BACK TO THE RAINY SEASON VERSION OF TRADE-WIND SHOWERS BY TUESDAY. NO SIGNIFICANT FEATURE IS INDICATED AFTER THIS TIME FRAME BY ANY NWP MODEL. WAVES AND SEAS ARE EXPECTED TO REMAIN LOW DURING THIS FORECAST PERIOD. LITTLE TO NO INFLUENCE IS EXPECTED FROM TYPHOON FANAPI...TOO SMALL AND TOO FAR AWAY. && .EASTERN MICRONESIA... LITTLE CHANGE TO PRIOR FORECAST AND REASONING. 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 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 VISIBLE ON BOTH ASCAT AND SATELLITE IMAGERY. THIS AREA IS NOW WEST OF KOROR WITH KOROR TEMPORARILY IN THE CLEAR...BUT WITH A TROUGH APPROACHING BUT BLOCKED BY THE RIDGE TO THE WEST. YAP IS NORTH OF MOST OF THE ACTIVITY THIS EVENING. AS A SURFACE TROUGH MOVES WESTWARD IT WILL CAUSE THE CONVERGENCE ZONE TO SHIFT NORTHWARD AND BRING WIDELY SCATTERED SHOWERS 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 SOUTHEAST OF YAP AND KOROR. THIS ELEMENT CAN BRIEFLY DECREASE SHOWER COVERAGE OVER THE WEEKEND BUT A WETTER PATTERN WILL LIKELY RETURN BY NEXT WEEK AS MORE DISTURBANCES ARE PRESENT UPSTREAM. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...NONE. MARIANAS WATERS...NONE. && $$ EDSON/DEVITA +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.