WPAC: Ex DIANMU

[Chacor]

JMA at 0600z:
LOW PRESSURE AREA 1004 HPA NEAR 18N 122E WSW 15 KT.

[KWT]

There does look like there is some turning up there but it looks weak and is pretty much void of any deep convection, could do something I suppose further west.

[StormingB81]

JMA at 0600z:
LOW PRESSURE AREA 1004 HPA NEAR 18N 122E WSW 15 KT.

isnt this still the one from 97? The other one looks to be ESE of that low?

[supercane]

From NRL KML file:


Tropical Cyclone 96W

06 Aug 2010 0000Z
Location: 17.3 130.3
Winds: 15 knots
Central Pressure: 1010 hPa



Note that NRL seems to have gotten caught up in the whole PAGASA Domeng confusion with their position 2 days ago.

[supercane]

[cycloneye]

Nothing yet from JMA?

[supercane]

96L's low not listed on JMA's 18Z analysis. Interestingly they focus on a system on the other side of Luzon:

WWJP25 RJTD 051800
WARNING AND SUMMARY 051800.
WARNING VALID 061800.
WARNING IS UPDATED EVERY 6 HOURS.
GALE WARNING.
DEVELOPING LOW 1002 HPA
AT 48N 135E MARITINE TERRITORY MOVING EASTNORTHEAST 25 KNOTS.
WARM FRONT FROM 48N 135E TO 49N 141E 49N 147E.
COLD FRONT FROM 48N 135E TO 44N 131E 41N 126E 38N 124E.
STATIONARY FRONT FROM 38N 124E TO 36N 121E 34N 116E.
WINDS 30 TO 35 KNOTS WITHIN 400 MILES OF LOW SOUTH SEMICIRCLE AND 300
MILES ELSEWHERE.
ANOTHER LOW 1002 HPA AT 53N 141E
MOVING EAST 15 KNOTS.
WARNING.
DENSE FOG OBSERVED LOCALLY OVER SEA OF OKHOTSK NORTHERN PART OF SEA
OF JAPAN MIDDLE OF SEA OF JAPAN YELLOW SEA.
WARNING.
DENSE FOG OBSERVED LOCALLY OVER WATERS BOUNDED BY 36N 141E 42N 142E
47N 152E 55N 162E 60N 164E 60N 180E 34N 180E 34N 170E 37N 147E 36N
141E.
SUMMARY.
LOW 1016 HPA AT 45N 167E EAST 20 KT.
LOW 1026 HPA AT 37N 179W WEST SLOWLY.
LOW PRESSURE AREA 1004 HPA NEAR 17N 118E WSW 20 KT.
HIGH 1026 HPA AT 35N 161E WEST SLOWLY.

JAPAN METEOROLOGICAL AGENCY.=


Still awaiting 00Z update.

[supercane]

Again 00Z JMA analysis focuses on low pressure west of Luzon and not on 96W.

WWJP25 RJTD 060000
WARNING AND SUMMARY 060000.
WARNING VALID 070000.
WARNING IS UPDATED EVERY 6 HOURS.
GALE WARNING.
DEVELOPING LOW 1000 HPA
AT 53N 145E SEA OF OKHOTSK MOVING EAST 15 KNOTS.
WINDS 30 TO 35 KNOTS WITHIN 400 MILES OF LOW SOUTH SEMICIRCLE AND 300
MILES ELSEWHERE.
WARNING.
DENSE FOG OBSERVED LOCALLY OVER SEA OF OKHOTSK NORTHERN PART OF SEA
OF JAPAN MIDDLE OF SEA OF JAPAN YELLOW SEA.
WARNING.
DENSE FOG OBSERVED LOCALLY OVER WATERS BOUNDED BY 38N 141E 42N 142E
51N 157E 60N 164E 60N 180E 36N 180E 38N 160E 38N 141E.
SUMMARY.
LOW 1014 HPA AT 45N 170E EAST 15 KT.
LOW 1024 HPA AT 36N 179W NNE SLOWLY.
LOW PRESSURE AREA 1004 HPA NEAR 18N 117E WEST SLOWLY.
HIGH 1028 HPA AT 35N 154E WEST 10 KT.
STATIONARY FRONT FROM 33N 116E TO 38N 125E 41N 129E 45N 135E 49N 139E
50N 145E 49N 151E.

JAPAN METEOROLOGICAL AGENCY.=

Did analysis in Digital Atmosphere (not shown) which agrees that lowest pressure around Luzon, but there does appear to be a general low pressure east of Luzon, maybe around 1009 mb?

[supercane]

High shear environment:



NWS Guam's take:


000
ATPQ40 PGUM 051529
SIMGUM

SATELLITE INTERPRETATION MESSAGE
NATIONAL WEATHER SERVICE TIYAN GU
100 AM CHST FRI AUG 6 2010

WESTERN NORTH PACIFIC BETWEEN EQUATOR AND 25N FROM 130E TO 180.

A SURFACE TROUGH STRETCHES EASTWARD FROM A MONSOON CIRCULATION OVER
LUZON THROUGH 18N130E TO WEST OF THE NORTHERN CNMI AT 19N139E...THEN
TURNS NORTHEASTWARD TO BEYOND 25N AT 147E. DIVERGENT UPPER-LEVEL
WINDS ARE ENHANCING NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS
NEAR THE TROUGH AXIS NORTH OF PALAU BETWEEN 14N AND 19N FROM 130E TO
135E. SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE OCCURRING
FARTHER EAST...WEST OF GUAM AND SAIPAN BETWEEN 13N AND 20N FROM 135E
TO 144E. SIMILAR CONDITIONS ARE ALSO SEEN OVER THE NORTHERN CNMI
WITHIN 65 MILES OF A LINE FROM 16N146E TO 24N151E...AND SOUTHEAST OF
IWO TO ISLAND OR NORTH OF A LINE FROM 22N142E TO 22N148E TO 24N150E.

CONVERGING SOUTH WINDS TO THE SOUTH OF THE SURFACE TROUGH ARE
PRODUCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WEST OF KOROR
BETWEEN 6N AND 13N FROM 130E TO 132E...AND OVER YAP WITHIN 150 MILES
OF A LINE FROM EQ135E TO 11N140E.

TRADE-WIND CONVERGENCE IS COUPLING WITH UPPER-LEVEL DIVERGENCE TO
CREATE SCATTERED SHOWERS AND A FEW THUNDERSTORMS EAST OF THE
MARIANAS WITHIN 165 MILES OF A LINE FROM 12N150E TO 23N156E.
IDENTICAL WEATHER IS ALSO FOUND OVER CHUUK AND POHNPEI BETWEEN 2N
AND 11N FROM 145E TO 162E...AND SOUTHEAST OF YAP BETWEEN THE EQUATOR
AND 6N FROM 140E TO 145E.

$$

CHAN

[Typhoon10]

Sorry guys, am still learning. But how does "Shear" affect the chances of a storm, or when a system is already present?

[Macrocane]

Sorry guys, am still learning. But how does "Shear" affect the chances of a storm, or when a system is already present?

Vertical wind shear is the difference in the windspeed in the different levels of the atmosphere, if the winds in the upper level are stronger than the winds in the low level the thunderstorms can be blown away from the center of a tropcial cyclone, if that center is left without those storms then the cyclone can't intensify and will begin to weaken.

[Typhoon10]

Sorry guys, am still learning. But how does "Shear" affect the chances of a storm, or when a system is already present?

Vertical wind shear is the difference in the windspeed in the different levels of the atmosphere, if the winds in the upper level are stronger than the winds in the low level the thunderstorms can be blown away from the center of a tropcial cyclone, if that center is left without those storms than the cyclone can't intensify and will begin to weaken.

Thanks for that, appreciate it. I dont know where all you "experts" leanrnt all this, ideally I would like to go on a course or something to get better educated about it

[supercane]

Good explanation. A picture from the COMET TC chapter:

[Macrocane]

Thanks for that, appreciate it. I dont know where all you "experts" leanrnt all this, ideally I would like to go on a course or something to get better educated about it

Well I still have a lot to learn but this forum is a great place to do it, I also like to read the advisories and warnings from the different agencies and the discussions from different weather sites, I'm sure you will learn a lot here and it's good to ask questions that's one of the best ways of learning.

[supercane]

Agree with macrocane also. Best way is to observe each storm, read discussions here and from agencies (NHC and JTWC), and think about how the environmental factors affect the system's evolution. Perhaps the easiest introduction would be the AOML's Hurricane FAQ.

[RL3AO]

Looks like one of those huge gyro systems trying to develop.

[Typhoon10]

Looks like one of those huge gyro systems trying to develop.

Hi RL3, for us novices can you expand on what you mean in laymans terms please?

[supercane]

Unfortunately the monsoon gyre is somewhat complicated to describe. If you have enough of a technical background, you can try Mark Lander's "Description of a Monsoon Gyre and Its Effects on the Tropical Cyclones in the Western North Pacific during August 1991" from Weather and Forecasting, Volume 9, Issue 4 (December 1994) pp. 640-654.

[supercane]

From the abstract of Lander's paper cited above:

The specific configuration of the monsoon circulation, which herein is called a monsoon gyre, is an episodic event-occurring roughly once per year, for two or three weeks during July, August, or September. As a monsoon gyre, the low-level circulation of the WNP becomes organized as a large cyclonic vortex associated with a nearly circular 2500-km-wide depression in the contours of the sea level pressure. A cyclonically curved band of deep convective clouds rims the southern through eastern periphery of this large vortex. Once this pattern is established, it becomes a prolific generator of mesoscale vortices that emerge from the downstream end of the major peripheral cloud band. These mesoscale vortices form the seed disturbances for midget or small-sized tropical cyclones.

[supercane]

Monsoon gyre definition from AMS's Glossary of Meteorology:

monsoon gyre—A convection of the summer monsoon circulation of the western North Pacific characterized by 1) a very large nearly circular low-level cyclonic vortex (not the result of the expanding wind field of a preexisting monsoon depression or tropical cyclone) that has an outermost closed isobar with a diameter on the order of 1200 n mi (2500 km); 2) a cloud band bordering the southern through eastern periphery of the vortex/surface low; and 3) a relatively long (two week) life span.
Initially, a subsequent regime exists in its core and western and northwestern quadrants with light winds and scattered low cumulus clouds; later, the area within the outer closed isobar may fill with deep convective cloud and become a isobar or tropical cyclone. Note: a series of midget tropical cyclones may emerge from the “head” or leading edge of the peripheral tropical cyclone of a monsoon gyre.