Typhoon Mirinae kills dozens in Vietnam and Philippines; More Heavy rain for Filipinos November 3, 2009

Filipinos Honor Dead in Cemeteries in boats on All Saints Day

Mirinae brought flooding to Vietnam

Typhoon Mirinae had one last gasp before making a second landfall in Vietnam (see video).  As I had last reported, the microwave imagery showed that an eye was forming again as the storm moved from the Philippines across the South China Sea.  It had been downgraded to tropical storm status but the JTWC increased its intensity following the microwave observation.  It was not expected to continue strengthening though due to some sheer and also colder water temperatures.  The microwave image even detected an erosion of the eye structure.  Well, it got a bit of a kick and continued to intensify, back to Typhoon status just prior to making landfall in Vietnam.   The moniker really made no significant difference because the true threat from the storm was always the heavy rain potential.  Early reports say that Typhoon Mirinae killed anywhere from 23 to 40 in Vietnam but, these are preliminary reports. 

Meanwhile, the death toll from Typhoon Mirinae in the Philippines was put at 19 by Channel News Asia (see photo gallery) but broadcast reports now say that the number has risen to 20.  I’m not sure if it’s a political move or not, but officials in the Philippines are saying that preparation is what kept the death toll from not being anywhere close to that of Typhoon Parma and Typhoon Ketsana which collectively killed over 900.  Now, the government was criticized for not reacting stronger to the threat from Ketsana and Parma.  So, it’s possible that officials are just taking credit to help their image with the voters.  But, here’s the thing.  I’m not aware of what the government did or didn’t do with the previous storms but with the amount of rain that the Philippines got and the terrain of the nation and the location of villages in that country in relation to that terrain, I’m not sure what people expected the government to do.  They can’t stop the rain nor the ensuing flooding or mudslides.  Conversely, with this storm, the death toll was probably held down due to the speed of Mirinae as it moved across the island, thus decreasing rain totals, than anything the government did.  Man and its governments can only do so much when dealing with the forces of nature and governments often get too much blame or too much credit when dealing with weather events.  As US Grant was fond of saying, “Man proposes, God disposes.”

The second tropical cyclone that looked from all data that it would follow right behind Mirinae into the  Northern Philippines was upgraded to a tropical depression.  It began to fall apart but, like Mirinae, the intensity was never the issue. It was rain and now it has moved into Luzon Province and is dropping heavy rain.  This could be problematic in that this guy is not moving as quickly as Mirinae.

Remant of Typhoon Mirinae Moving Toward Vietnam; Leaves 14 dead, flooding in Philippines November 1, 2009

Note Mirinae and Developing Cyclone east of Philippines in loop

Philippines Def. Minister visits Barangay Callos in Laguna (click for photo gallery)

Typhoon Mirinae is well west of the Philippines(see discussion below).  Reports are that the number of deaths in the Philippines rose to 14 with significant flooding reported in numerous villages.  See CNN story and video here.   I still can’t get any reports concerning activity at Mount Mayon so I suppose that means it is behaving itself.  There is another tropical cyclone (see discussion below) trying to get going to the east of the Philippines.  A ship near the center of circulation (about 60 nm away) some 595 km east of Manila reported a pressure of 1007.5 mb which really isn’t that low.  I have yet to see any data that supports any huge development but the JTWC still gives the prospects of significant development at “fair.”  Since rain is the issue, I suspect that the biggest problem with this system is its very existance, which was noted several days ago on models.  At that time, the models called for this system to move west over the Philippines and so far, the system is following the guidance.  It has been observed moving west at 12 knots.  While this is not slow, it is of concern because if it continues at this pace and course, it may bring a good chance of rain, perhaps heavy rain for a decent amount of time over the Philippines in the next couple of days.

Typhoon Mirinae Forecast Track (downgraded to Tropical Storm)

Typhoon Mirinae has been downgraded to a tropical storm as it moves across the South China Sea on a west southwesterly course.  The official track calls for it to continue to move toward Vietnam and make a second landfall on the coast northeast of Ho Chi Minh City.  Recently, microwave imagery indicated an eye trying to reform and winds have increased to 50 kts.  However, the environment seems in the future to not be too favorable and the most recent observations indicate that the newly formed eye is already deteriorating.  Therefore,  Vietnam can expect a weak to moderate tropical storm making landfall just prior to 12Z November 2.  The remnant of the storm will continue toward Phnom Phen in eastern Cambodia where it may dissipate.  The danger is not done though because quite often the remnant of a tropical cyclone can produce an abundance of rain, as exemplified by Tropical Storm Claudette in the 1970′s and more recently Tropical Storm Allison in the Houston area, both of which caused horrific flooding along the upper Texas Coast. 

Microwave loop shows some attempt at development by Mirinae

WDPN32 PGTW 011500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (MIRINAE) WARNING
NR 27//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. TROPICAL STORM (TS) 23W (MIRINAE) WEAKENED TO 40 KNOTS AT
0600Z AND, ACCORDING TO RECENT DVORAKS FROM PGTW AND KNES, HAS
STRENGTHENED TO 50 KNOTS MORE RECENTLY. A 010955Z SSMI 37H MICROWAVE
IMAGE INDICATES A WEAK MICROWAVE EYE, WHICH GENERALLY CORRESPONDS TO
A SYSTEM GREATER THAN 45 KNOTS. GIVEN THE LARGE AREA OF CONVECTION
THAT HAS BUILT OVER THE LOW LEVEL CIRCULATION CENTER, THE INCREASED
DVORAK INTENSITY ESTIMATES, AND THE MICROWAVE EYE, THE INITIAL
INTENSITY HAS BEEN INCREASED TO 50 KNOTS. HOWEVER, CLOUD TOP
TEMPERATURES HAVE ALREADY BEGUN TO WARM SLIGHTLY AND THE CONVECTION
HAS BEGUN TO FLARE. A 011126Z SSMIS MICROWAVE IMAGE ALSO SHOWS THAT
THE MICROWAVE EYE FEATURE HAS ALSO BEGUN TO DEGRADE, AND OPEN UP ON
THE SOUTH SIDE. THESE OBSERVATIONS ARE INDICATIONS THAT THIS
INTENSIFICATION IS SHORT TERM, AND DUE POSSIBLY TO DIURNAL EFFECTS.
THE STORM CONTINUES TO TRACK SOUTH OF WEST TOWARDS VIETNAM UNDER THE
INFLUENCE OF THE SUBTROPICAL RIDGE TO THE NORTH.
3. FORECAST REASONING.
    A. THE FORECAST REASONING HAS NOT CHANGED SIGNIFICANTLY SINCE
THE PREVIOUS PROGNOSTIC REASONING BULLETIN WITH THE EXCEPTION OF THE
SHORT TERM INTENSIFICATION DESCRIBED IN PARA 2.A. THE STORM IS STILL
EXPECTED TO WEAKEN PRIOR TO MAKING LANDFALL WITH VIETNAM.
B.  TS 23W WILL BEGIN TO TRACK WEST-SOUTHWESTWARD AS IT TRACKS ALONG
THE SOUTHERN PERIPHERY OF THE MID-LEVEL SUBTROPICAL RIDGE TO THE
NORTH. THE NORTHEASTERLY COLD SURGE WILL STRENGTHEN OVER THE NEXT 12
TO 24 HOURS, WHICH WILL ACCOUNT FOR INCREASED VERTICAL WIND SHEAR
AND A MORE STABLE ENVIRONMENT. THESE FACTORS WILL CONTRIBUTE TO A
SLOW WEAKENING PRIOR TO MIRINAE MAKING LANDFALL WITHIN 24 HOURS. THE
STORM IS EXPECTED TO DISSIPATE OVER EASTERN CAMBODIA THERE AFTER,
THOUGH THE REMNANT VORTICITY MAY TRACK FURTHER WESTWARD (AS
INDICATED BY MANY OF THE OBJECTIVE AID MEMBERS) INTO THE GULF OF
THAILAND OR BAY OF BENGAL. REDEVELOPMENT OF THE LLCC DOES NOT APPEAR
PROBABLE IN EITHER CASE.//
NNNN

ABPW10 PGTW 010600
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/SIGNIFICANT TROPICAL WEATHER ADVISORY FOR THE WESTERN AND
/SOUTH PACIFIC OCEANS/010600Z-020600ZNOV2009//
REF/A/MSG/NAVMARFCSTCEN PEARL HARBOR HI/010152ZNOV2009//
AMPN/REF A IS A TROPICAL CYCLONE WARNING.//
RMKS/
1. WESTERN NORTH PACIFIC AREA (180 TO MALAY PENINSULA):
   A. TROPICAL CYCLONE SUMMARY:
      (1) AT 010000Z, TROPICAL STORM 23W (MIRINAE) WAS LOCATED NEAR
13.9N 115.4E, APPROXIMATELY 545 NM EAST-NORTHEAST OF HO CHI MINH,
VIETNAM, AND HAD TRACKED WESTWARD AT 12 KNOTS OVER THE PAST SIX
HOURS. MAXIMUM SUSTAINED SURFACE WINDS WERE ESTIMATED AT 40 KNOTS
GUSTING TO 50 KNOTS. SEE REF A (WTPN32 PGTW 010300) FOR FURTHER
DETAILS.
      (2) NO OTHER TROPICAL CYCLONES.
   B. TROPICAL DISTURBANCE SUMMARY:
      (1) THE AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 14.6N
132.3E, IS NOW LOCATED NEAR 16.0N 131.2E, APPROXIMATELY 595 NM EAST
OF MANILA, PHILIPPINES. AN OCEANOGRAPHIC RESEARCH SHIP, CALL SIGN
MELVILLE, REPORTED 12-KNOT EASTERLIES AND SEA LEVEL PRESSURE AT
1007.5 MB AT 010000Z. MELVILLE IS LOCATED APPROXIMATELY ONE DEGREE
TO THE SOUTH-SOUTHEAST OF THE LOW LEVEL CIRCULATION CENTER (LLCC).
VARIOUS METSAT IMAGERY, INCLUDING A 312233Z SSMIS, INDICATES
PRONOUNCED CURVATURE OF THE CLOUDS PREDOMINATELY WITHIN THE
NORTHWEST QUADRANT. DESPITE THIS SIGNATURE THE LLCC IS DIFFICULT TO
LOCATE AND THE CONVECTION IS VERY WEAK OVERALL. THE MOST RECENT
SCATTEROMETRY DATA (NEARLY 18 HOURS OLD) INDICATE VERY STRONG
EASTERLIES TO THE NORTH OF THE LLCC, BUT LIGHT SUPPORTING WESTERLIES
TO THE SOUTH. THE UPPER LEVEL ENVIRONMENT REMAINS FAVORABLE WITH
LIGHT TO MODERATE VERTICAL WIND SHEAR, AND A JET MAXIMUM TO THE
NORTH AIDING (EASTWARD) VENTING. MAXIMUM SUSTAINED SURFACE WINDS ARE
ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED
TO BE NEAR 1007 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A
SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS FAIR.
      (2) NO OTHER SUSPECT AREAS.
2. SOUTH PACIFIC AREA (WEST COAST OF SOUTH AMERICA TO 135 EAST):
   A. TROPICAL CYCLONE SUMMARY: NONE.
   B. TROPICAL DISTURBANCE SUMMARY: NONE.//

Typhoon Mirinae leaves flooding and death in Philippines as it heads to Vietnam October 31, 2009

Click on Image for most recent loop of Typhoon Mirinae

For latest news on death,flooding in Philippines and Mirinae track to vietnam(including microwave imagery) CLICK HERE

Click Image for latest Forecast Track of Typhoon Mirinae, now a tropical storm

Government run relief shelters in the Philippines are sure to swell in numbers from the effects of Typhoon Mirinae.   Typhoon Mirinae struck the main island of Luzon around 17 Z October 30 as the third typhoon to hit the Philippines in the past month.  Typhoon Lupit also brushed the northeast tip of the Philippines just a week ago.  Well over 100,000 Filipinos were still in shelters as a result of the flooding from Typhoon Ketsana and Typhoon Parma which struck back-to-back in late September and early October.  Many villages were still flooded from those two calamities that killed over 900.   The death toll in the Philippines from Typhoon Mirinae stands at a dozen and at least 15 villages are flooded with up to waist deep water.  This is on top of numerous villages that remained flooded from the previous storms.    The last report concerning Mount Mayon put the active volcano at a level two alert as just  prior to the landfall of Typhoon Mirnae, Mount Mayon had exhibited behaviour of increased activity.  Numerous earthquakes from the volcano accompanied minor eruptions of ash plumes but authorities had a dificult time making observations of a potential rising lava dome in the crater.

Watch 72hr loop of Total Precipitable Water Showing Movement of Typhoon Mirinae

Typhoon Mirinae has been downgraded to a tropical storm as it moves away from the Philippines at about 20 kts.  It is expected to continue moving west-southwest toward South Central Vietnam.  The official forecast calls for a second landfall just after 00Z November 2 a couple of hundred miles north of Ho Chi Minh City and continue towards Phnom Penh in Cambodia, though some models still call for a landfall a bit farther south to the east of Ho Chi Minh City.   A second tropical system has developed to the east of the Philippines and, while it is not expected to become a typhoon, the current track would take it over the Philippines in the next couple of days and would bring the threat of additional rainfall.  The system will be monitored for development.

Typhoon Mirinae Forecast: Philippines Landfall as Volcano Threatens Eruption October 30, 2009

Typhoon Mirinae Will Stirke the Philippines

Typhoon Mirinae 23:13Z Oct 29 Vis with low level wind barbs

Typhoon Mirinae will hit the Luzon province in the Philippines.  It’s possible that Mother Nature may also erupt a volcano at the same time.  The Typhoon Mirinae Forecast Track is very similar to that of Typhoon Ketsana.  The difference will be that it’s forward momentum will continue and therefore will not remain over the Philippines for an extended period of time. 

Typhoon Mirinae Forecast Track click for most recent map

The Typhoon Mirinae Forecast Track takes it into the Philippines almost due east of Manila and it re-emerges in the South China Sea almost due west of Manila.  There is some sense of continuity with the computer models.  The NOGAPS calls for a landfall at just around 12Z October 30 as a tropical cyclone with a central pressure a shade less than 992 mb.  The NOGAPS suggests that the center of circulation will be just west of Manila by 06Z October 31 with a pressure of something less than 1000 mb.  Now, the GFS is a bit different as it wants to weaken the storm prior to landfall to less than 1000 mb and has it exit as a 1004 mb low.  It too calls for a landfall in the neighborhood of 12Z October 30 with it moving offshore west of Manila by 6Z October 31.  A few days later, Mirinae is forecast to weaken somewhat over colder water in the South China Sea before making a second landfall in Vietnam before moving into Cambodia.   

Watch 72hr loop of Total Precipitable Water Showing Movement of Typhoon Mirinae

The official forecast track as of 00Z October 30 from the Joint Typhoon Warning Center calls for Typhoon Mirinae to make landfall east of Manila sometime between 12z and 18Z on October 30 and has it offshore of Manila by about 02Z October 31.  Other models must call for the faster speed as the NOGAPS and GFS call for the storm to be over land for about 18 hours whereas the boys at the JTWC are thinking more along the lines of 12 hours.  The folks in the Philippines will be hoping that the JTWC is correct because the faster pace will reduce the time of heavy rain over the island.  Still, several hours of heavy rain will be in the cards and winds will initially be running around 90 kts (100 mph) at landfall with higher gusts.  The storm’s forward speed will also mean that typhoon strength winds will be felt by everyone in the path of the center of circulation because, though weakened, it will still be a minimal typhoon when it moves back offshore in all liklihood.  Over 100,000 Filipinos remain in evacuation shelters from the effects of Typhoon Ketsana and Typhoon Parma which collectively killed over 900 people.  Many have been affected by the rapid spread of the disease known as Leptospirosis.  The government is warning for the potential for flooding and landslides so more people have been evacuated from vulnerable locations. 

Keep Up with latest 3 hour rainfall estimates from NASA's TRMM

If that is not enough for the Philippines….as Typhoon Mirinae makes landfall, Mount Mayon in the Philippines is making noises and there is a fear that Mount Mayon, the most active volcano in the Philippines may erupt while Mirinae is over the island or shortly thereafter.    The active volcano is one of many volcanic peaks in the Philippines and has been responsible for well over a dozen volcanic earthquakes and has begun spewing ash and sulpher dioxide into the air.  It last had an ash eruption on September 15.  Officials have been trying to get a look at the crater to determine if the dome forming there is indeed a lava dome or if its simply a case of magma below the surface pushing old rock to the surface.  Trouble is, they can’t make aerial examinations of the crater on top of Mount Mayon due to cloud cover and with the advance of Typhoon Mirinae, which the Philippines weather authorities designated as Typhoon Santi (why they have different names is a mystery to me), they won’t be able to make any observations.  So, Philippines Volcano Monitoring authorities  issued a level 2 alert warning the residents around the volcano and are enforcing a strict ban on people entering a zone around Mayon. 

Mayon one of many volcanoes in the Philippines

If they issue a  level 3 alert, then some 30,000 residents around the volcano will have to be evacuated.  There is great concern here because Mayon’s crater holds over 200,000 cubic feet of rocks.  There is fear of an eruption with lava flows.  Even of greater concern is the threat of a Lahar,the fast moving flow of mud, water and perhaps lava that can sweep down from volcanoes.  Heavy rains may enhance that threat and official say that in a worst  case scenario, they may have to evacuate some 300,000 people from Lahar zones.   However, Mount Mayon is pretty far south of the forecast landfall location.  Should Mirinae make landfall as the JTWC suggests, then the greatest rainfall should be well north of Mount Mayon.

WDPN32 PGTW 300300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 23W (MIRINAE) WARNING NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. TYPHOON MIRINAE HAS TRACKED WEST-SOUTHWESTWARD AT 17 KNOTS 
OVER THE PAST 12 HOURS AND SUSTAINED AN INTENSITY OF 90 KNOTS. 
THOUGH THE CYCLONE STILL HAS SOME WESTWARD BLOWING CONVECTION, 
INDICATING THE PRESENCE OF EASTERLY VERTICAL WIND SHEAR, A SMALL 
ANTICYCLONE ALOFT HAS ENABLED CONTINUED RADIAL OUTFLOW. WHILE 
MIRINAE WAS PREVIOUSLY MAINTAINING A CENTRAL DENSE OVERCAST PATTERN 
THAT MADE POSITIONING USING INFRARED AND VISIBLE IMAGERY DIFFICULT, 
IT HAS RECENTLY STARTED TO DEVELOP MORE OF A BANDING EYE FEATURE. 
THEREFORE, IN COMBINATION WITH THE 292259Z 37 GHZ SSMIS MICROWAVE 
IMAGE, THE CURRENT POSITION IS PLACED WITH GOOD CONFIDENCE. 
SIMILARLY, THE CURRENT INTENSITY IS BASED ON CONSISTENT DVORAK 
ESTIMATES FROM PGTW, RJTD AND KNES OF 90 KNOTS. 
3. FORECAST REASONING.
    A. THE FORECAST REASONING HAS NOT CHANGED SINCE THE PREVIOUS 
PROGNOSTIC REASONING BULLETIN. 
    B. TYPHOON MIRINAE WILL CONTINUE TRACKING WESTWARD ALONG THE 
SOUTHERN PERIPHERY OF THE WELL-ESTABLISHED SUBTROPICAL RIDGE. THE 
SYSTEM IS EXPECTED TO MAKE LANDFALL IN CENTRAL LUZON AROUND TAU 18 
AND SLOW SLIGHTLY (BY APPROXIMATELY 2-3 KNOTS) IN FORWARD TRACK 
SPEED WHILE DECREASING BY 15 TO 20 KNOTS IN INTENSITY. AFTER TAU 24, 
MIRINAE IS EXPECTED TO ENTER THE SOUTH CHINA SEA ON A WESTWARD TRACK 
AND CONTINUE TO STEADILY WEAKEN UNDER THE INFLUENCE OF INCREASINGLY 
UNFAVORABLE VERTICAL WIND SHEAR ASSOCIATED WITH THE COMBINATION OF 
EASTERLY FLOW SOUTH OF THE SUBTROPICAL RIDGE AXIS (MID-LEVELS) AND 
NORTHEASTERLY FLOW INDUCED BY AN EARLY-SEASON COLD SURGE.
    C. MIRINAE WILL MAKE LANDFALL IN SOUTH-CENTRAL VIETNAM JUST 
AFTER TAU 72 AND WILL DISSIPATE OVER LAND AS A SIGNIFICANT TROPICAL 
CYCLONE BY TAU 96. THE MODEL GUIDANCE IS IN GOOD AGREEMENT WITH A 
SOUTHWESTWARD TRACK THROUGH THE SOUTH CHINA SEA. HOWEVER, SOME OF 
THE MODEL AIDS, INCLUDING THE JAPANESE SOLUTION, TAKE THE SYSTEM 
JUST SOUTH OF MANILA, PHILIPPINES AND TOWARDS HO CHI MINH CITY, 
VIETNAM.//
NNNN

Typhoon Mirinae Forecast Track Points to Luzon, Philippines Landfall at end of week October 29, 2009

Typhoon Mirinae Appears Certain to Strike the Philippines

For news of flooding, deaths in Philippines and Mirinae track to Vietnam CLICK HERE

Typhoon Mirinae Forecast Track click for most recent map

The Typhoon Mirinae Forecast Track remains generally unchanged as does the intensity.  It continues to move west at a pretty good clip and that may end up being a good thing for the Philippines.   The JTWC forecast track has been nudged a tad farther south than previous runs which would send the typhoon across the island closer to Manila.  While Luzon really can’t handle a lot of rain, it’s going to get it as well as winds along the coast perhaps as high as 105 to 110 mph or 95 kts with higher gusts.  With the forward momentum of Mirinae, I suspect that whatever the maximum storm surge in that area with this type of storm will be likely.  The biggest difference between the NOGAPS and GFS models is the timing.  Over 117,000 Filipinos remain in shelters as a result of Typhoon Parma and Tropical Storm Ketsana.  So, the government of the Philippines is warning the potential for  landslides and flooding.  The government is particularly concerned because All Saints Day, November 1, is traditionally a day when Filipinos visit cemeteries to remember ancestors.

Typhoon Mirinae Satellite Loop Click for most recent loop

The NOGAPS advertises a typhoon moving at a pretty good pace with a landfall outlined just prior to 12Z on Friday October 30.  It also favors a landfalling tropical cyclone with a central pressure a shade less than 996 mb.  The GFS on the other hand doesn’t come up with as robust a system as the NOGAPS.  The central pressure at landfall is something between 996 mb and 100 mb.  If that is verified, I find it hard to determine how a storm with that level of pressure could support the JTWC contention that a 95 kt typhoon will strike the Philippines.  My experience tells me that pressures that high generally does not support winds of 95 kts unless it was a major tropical cyclone that was winding down and even that is not evidence of support.  Falling winds mean that the pressure cannot support that wind level.    Other than that, the GFS is much slower than the NOGAPS with a landfall with a landfall not coming until just after 00Z on Saturday Oct 31.  That is a big difference because if Mirinae moves that slowly then it would be dropping heavy rain on the Philippines for many hours longer than the NOGAPS solution. 

Typhoon Mirinae Water Vapor Loop click for most recent loop

The typhoon has been moving at a steady speed and so unless something shows up to slow its forward speed then it seems reasonable that the JTWC forecast of having the core of the storm over Luzon for less than 24 hours is very plausible.  On the other hand, that also means that the fine folks of Manila and other parts of the Philippines will probably experience pretty decent winds….maybe even typhoon force…for the duration of the storm because Mirinae just wouldn’t have time to fall apart…but it will weaken.  This storm got stronger than anticipated due to a trof to the north that was enhancing the outflow to the north.  Interestingly, that trof was actually created from the remnant of Typhoon Lupit which moved northeast offshore of Japan, turned extratropical and created a front trailing off from it.  With that feature moving out,  there isn’t any real mechanism that would help enhance the intensity substantially.  The only thing that will help it get stronger is an increasing outflow aloft, but that will be offset somewhat by a little bit of vertical shear.  The JTWC notes that the shear has already messed up the visibility of the eye. 

Watch 72hr loop of Total Precipitable Water Showing development of Typhoon Mirinae

If one assumes a rapid movement across the Philippines, then one might assume that the storm will not deteriorate that much over land and will emerge in the South China Sea in good shape.  So good that it may redevelop.  But, sea surface temperatures in the central South China Sea have dropped off a bit due to a recent shot of unseasonably cold air in the area.  So, the JTWC forecast reflects that situation by reducing the intensity of the storm as it approaches Vietnam.  Mirinae may fall to tropical storm status before landfall.  However, Vietnam also suffered from Typhoon Ketsana and Typhoon Parma, though Parma was closer to Hanoi.  In any event, the ground in Vietnam is pretty saturated so if they get a tropical storm instead of a typhoon, it is really immaterial as the forward motion will be the key for Vietnam.  Vietnam suffered over 3/4 of a billion US dollars just from Ketsana.   If the storm slows down once it’s inland over SE Asia, then excessive rainfall can be anticipated.  The thing that everyone wants is for the storm to keep moving. 

WDPN32 PGTW 290300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 23W (MIRINAE) WARNING NR 13//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. TYPHOON (TY) 23W (MIRINAE) HAS INTENSIFIED TO 90 KNOTS AND
MAINTAINED A WESTWARD TRACK UNDER THE INFLUENCE OF THE SUBTROPICAL
STEERING RIDGE OVER THE PAST 12 HOURS. RECENT ANIMATED MULTISPECTRAL
IMAGERY SHOWS EVIDENCE OF EASTERLY VERTICAL WIND SHEAR THAT HAS
CAUSED MIRINAE TO LOSE ITS EYE-LIKE FEATURE OVER THE LAST 12 HOURS.
HOWEVER, THE SYSTEM STILL HAS GOOD POLEWARD OUTFLOW INTO THE MID-
LATITUDE WESTERLIES AS WELL AS ACCESS TO POLEWARD OUTFLOW INTO THE
TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) LOCATED APPROXIMATELY 15
TO 20 DEGREES EAST OF THE SYSTEM. THE CURRENT POSITION IS BASED WITH
HIGH CONDIFENCE ON POSITION FIXES BY RJTD AND PGTW AND IS SUPPORTED
BY A 282127Z SSMI MICROWAVE IMAGE. THE CURRENT INTENSITY IS BASED ON
DVORAK ESTIMATES OF 90 KNOTS FROM PGTW AND RJTD.
3. FORECAST REASONING.
    A. THE FORECAST REASONING HAS NOT CHANGED SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
    B. THE TYPHOON WILL CONTINUE TO TRACK WESTWARD THROUGH THE
FORECAST PERIOD AND WILL RETAIN RADIAL OUTFLOW, ENABLING EXHAUST
INTO THE MID-LATITUDES, AS IT TRACKS SOUTH OF A NARROW SUBTROPICAL
RIDGE. FURTHER INTENSIFICATION IS EXPECTED TO BE LIMITED, MAINLY DUE
TO THE LACK OF A STRONG (POLEWARD) OUTFLOW CHANNEL AS THE SYSTEM
TRACKS FURTHER AWAY FROM THE TUTT MENTIONED IN PARA 2.A. MIRINAE IS
EXPECTED TO MAKE LANDFALL IN THE PHILIPPINES AND WEAKEN JUST BEFORE
TAU 48.
C. BEFORE TAU 72 THE SYSTEM WILL EXIT LUZON INTO THE SOUTH CHINA SEA
AS A MUCH-WEAKENED TYPHOON. A COOLER POOL OF SEA SURFACE TEMP-
ERATURES IN THE CENTRAL SOUTH CHINA SEA, MINIMAL OCEAN HEAT CONTENT
VALUES AND DIMINISHED POLEWARD EXHAUST WILL PROMOTE STEADY
WEAKENING. AN EARLY SEASON COLD SURGE WILL ALSO AID IN WEAKENING THE
SYSTEM CLOSER TO TAU 96. THE MODEL GUIDANCE IS IN STRONG AGREEMENT
WITH THIS FORECAST SCENARIO. THEY ALSO SHOW A GROWING TREND TOWARDS
A MORE SOUTHWESTERN TRACK IN THE EXTENDED TAUS.//

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