Typhoon Lupit Forecast and Behaviour Should Provide Optimism for Philippines


Western Pacific IR Color Loop click for latest

Western Pacific IR Color Loop click for latest

For update on brighter Typhoon Lupit Forecast Track CLICK HERE

Typhoon Lupit Forecast Track JTWC

Typhoon Lupit Forecast Track JTWC

The Typhoon Lupit Forecast Track scenario isn’t much changed from the previous post. It’s not even a Typhoon any longer.  While I think in the end, the data reflects potentially a much more positive outlook for the Philippines, Filipinos remain concerned about Typhoon, now Tropical Storm, Lupit.  And they should e concerned, but optimistic.  Really, there are very weak steering currents and I think its been drifting WSW mainly due to its own forward momentum.  The official forecast has it drift down toward Bataan on the northern edge of Luzon.  Then it kinda drifts just off the northern coast in the Luzon Strait.  I had noted yesterday that I thought that I saw some dry air within Lupit and now the JTWC makes note of that dry air which is responsible for further weakening.  The intensity of the storm is not really the issue.  The issue is rain.  If this scenario plays out, then the center of circulation stays just offshore and very heavy rains could persist over parts of Luzon for about 72 hours or so.  The flooding issue has always been the concern. 

TRMM 3 hour rainfall click for latest

TRMM 3 hour rainfall click for latest

Now, I had mentioned yesterday a weakness in the ridge to the north with the center over China getting broken down.  The JTWC suggests that a trof will plow through the flow and create a nice channel to the north of Lupit.  That would cause the storm to be influenced north and then race northeast.   That may put it onto a course for Japan similar to Typhoon Melor but I suspect that the turn would be sharp enough and early enough to keep the storm east of Japan.  I looked at the NASA TRMM satellite imagery and it indicates that the area in the ocean just northeast of the Philippines has gotten over 4 inches of rain in the past 24 hours.  So, from that simple comparison, it is possible that the Philippines could be receiving at least 3-5 inches of rain per day while the storm loiters offshore and right now, it would seem safe to assume the current forecast reasoning would keep the influence of Lupit on Luzon for about 3 days. 

Now, there is perhaps some good news.  I once had a colleague who told me of a professor that he had who reminded him all the time that the computer models were, in the end, just a piece of paper.  I had a professor, Dr. Norman K. Wagner, who used to say that as forecasters we often forget to look out the window and see what is really  happening.  Well, if you look at the Total Precipitable Water Loop (TPW) below, you can see that it would appear the storm may be drifting north already which would suggest that it was already getting influenced by a weakness in the ridge to the north.  This is my observation as of 23:38  EDT on Thursday.  It could just be a wobble.  But if it is an indication that it has started some movement northward, then Luzon may be in luck.  We’ll have to wait and see, but the 00Z 10.23.09 JTWC update will probably reflect this change.  If I had to bet, I’d say that Luzon will probably fare not nearly as badly as it once appeared it would.  But, no one will rest until Lupit is gone.

Total Precipitable Water Loop

Total Precipitable Water Loop

WDPN31 PGTW 230300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (LUPIT) WARNING NR
037//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. TROPICAL STORM (TS) 22W (LUPIT), LOCATED APPROXIMATELY 285 NM
NORTH-NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 03
KNOTS OVER THE PAST SIX HOURS. CURRENT POSITION IS BASED ON THE MOST
RECENT DVORAK SATELLITE FIX AND THE 222149Z MICROWAVE FIX FROM PGTW.
THE CURRENT INTENSITY ESTIMATE OF 60 KNOTS IS BASED ON ESTIMATES
FROM PGTW AND RJTD. RECENT ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS DEEP CONVECTION HAS BEEN IMPACTED BY MID- TO UPPER-LEVEL DRY
AIR INTRUSION ALONG THE NORTHWESTERN QUADRANT. TOTAL PRECIPITABLE
WATER PRODUCTS INDICATE THAT THE DRY AIR CROSSING OVER LUZON IS
BEGINNING TO WRAP TOWARDS THE CENTER, CAUSING A FURTHER DISRUPTION
IN ORGANIZATION OF DEEP CONVECTION. A RECENT 222245Z SSMIS PASS
SHOWS THAT THE WESTERN BANDING AND THE WESTERN WALL OF THE EYE ARE
SEVERELY IMPACTED BY DRY AIR ALONG THE WESTERN SIDE OF THE SYSTEM.
TS 22W CONTINUES TO TRACK IN A WEAK STEERING ENVIRONMENT BETWEEN THE
SUBTROPICAL RIDGE (STR) TO THE WEST AND THE STR TO THE EAST. AN
UPPER-LEVEL ANALYSIS OF THE REGION DEPICTS A WEAK FINGER OF THE
SUBTROPICAL RIDGE AT THE 700 TO 500 MB LEVELS IS STILL EXTENDING
WESTWARD TO THE NORTH OF TS 22W. THE SYSTEM IS CONTINUING TO SLOW AS
IT GETS DEEPER INTO AN ILL DEFINED STEERING ENVIRONMENT, BUT IS
STILL TRACKING WESTWARD UNDER THE INFLUENCE OF THE AFOREMENTIONED
RIDGE FINGER.
3. FORECAST REASONING
    A. THE FORECAST REASONING HAS NOT CHANGED SIGNIFICANTLY SINCE
THE PREVIOUS PROGNOSTIC REASONING BULLETIN.
    B. TY 22W IS EXPECTED TO CONTINUE SLOWING BEFORE EVENTUALLY
LOITERING IN THE STRAIT OF LUZON THROUGH TAU 72. THE PASSAGE OF A
MIDLATITUDE SHORTWAVE TROUGH AROUND TAU 6 THROUGH 12 WILL CAUSE THE
SYSTEM TO TRACK A BIT MORE POLEWARD AS THE FINGER OF THE RIDGE TO
THE NORTH ERODES SLIGHTLY. FOLLOWING THE PASSAGE OF THE TROUGH, THE
SYSTEM WILL RESUME DRIFTING TOWARDS THE WEST. NUMERICAL MODELS
REMAIN INCONSISTENT. ALL AVAILABLE GUIDANCE CONTINUES TO TRACK THE
SYSTEM TO THE NORTHEAST INTO THE FINGER OF THE RIDGE. HOWEVER,
NOGAPS, GFDN, ECMWF, AND UKMO NOW TRACK THE SYSTEM MUCH SLOWER
THROUGH TAU 72, AND THEN TRACK THE SYSTEM ERRATICALLY AFTER TAU 72.
THE MODELS ARE STILL UNSTABLE, AND THE FORECAST TRACK REMAINS ALONG
THE PERIPHERY OF THE ANALYZED FINGER OF THE RIDGE TO THE NORTHEAST.
THE VERY PROBABLE SCENARIO OF THE SYSTEM TURNING POLEWARD BY TAU 24
AND MOVING INTO THE WESTERLY MIDLATITUDE FLOW REMAINS AN ALTERNATE
SCENARIO IN RESPONSE TO THE MIDLATITUDE TROUGH, WEAKENING OF THE
RIDGE TO THE WEST, OR REORIENTATION OF THE STR TO THE EAST.
   C. AFTER TAU 72, THE SYSTEM WILL STILL BE IN A WEAK STEERING
ENVIRONMENT AND IS EXPECTED TO SLOWLY DRIFT TO THE NORTH AS THE
FINGER OF THE SUBTROPICAL RIDGE EVENTUALLY ERODES BACK TO THE EAST.
HOWEVER, AS THE SYSTEM CONTINUES TO WEAKEN IN THE FACE OF DRY AIR
AND INTERACTION FROM LAND, THE SYSTEM COULD WEAKEN TO THE POINT THAT
IT IS STEERED BY THE NORTHEASTERLY SURFACE FLOW AND TRACK INTO THE
SOUTH CHINA SEA.//
NNNN

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