Hurricane and Tropical Cyclones


Tropical Weather Discussion

axpz20 knhc 011004

Tropical weather discussion                                   
NWS National Hurricane Center Miami FL                       
1005 UTC Fri Aug 01 2014

Tropical weather discussion for the eastern Pacific Ocean from 
the Equator to 32n...east of 140w. The following information is 
based on satellite observations...radar...and 
meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through 
0830 UTC.

...Special feature...

The center of T.S. Iselle at 01/0900 UTC is near 13.5n 124.6w. 
Iselle is moving west-northwestward or 300 degrees 9 knots. The 
estimated minimum central pressure is 1002 mb. The maximum 
sustained wind speeds are 50 knots with gusts to 60 knots. 
Numerous strong convection is observed within 150 nm in the NE 
semicircle of the center of Iselle. Forecast/advisories on 
Tropical Storm Iselle are issued under WMO header wtpz24 knhc 
and under AWIPS header miatcmep4. 

...Tropical waves...

a tropical wave is along 107w/108w from 19n to 10n. Convective 
precipitation...numerous strong from 08n to 10n between 105w and 
108w. Scattered moderate isolated strong from 10n to 15n between 
100w and 110w. A 1008 mb low pres is noted at the southern end 
of the tropical wave along the ITCZ. A 04 UTC ascat satellite 
pass along with a concurrent altimeter satellite pass indicated 
limited winds and seas associated with this low. 

...Intertropical convergence zone/monsoon trough...

the monsoon trough extends from 09n85w to 08n94w to low pres 
near 11n110w 1008 mb to T.S. Iselle near 13n120w to low pres 
near 12n138w 1008 mb to beyond 12n140w. Scattered moderate to 
isolated strong convection is observed within 90 nm NE 
semicircle of low pres near 11n110w. Scattered moderate 
convection is observed within 90 nm S of axis between 125w and 


A sharp upper trough that had been in place between 120w and 
125w N of 15n appears to be dissipating. An upper anticyclone 
centered near 20n140w is extending a ridge eastward to 120w in 
place of the dissipating trough. This shift is curtailing the 
push of dry and stable air into the tropics W of 125w that had 
been in place a few days ago...and allowing eastern flow aloft 
south of 15n. As a result convection around T.S. Iselle...still 
in an area of weak steering flow to the se of the ridge axis... 
as been unhindered and continues become better organized. 

Farther west...convection has diminished considerably around the 
low near 12n138w. However an ascat satellite pass indicated 20 
to 25 kt winds between this low and the subtropical ridge to the 
north. Seas are estimated to be up to 9 ft in mixed se and NE 
swell over the next 24 to 36 hours N of this low as it drifts W 
of 140w.

The Gulf of papagayo...wind speeds are less than 20 knots now. 
The forecast is for northeast winds to 20 knots from the late 
night/early morning hours to noon on Friday. The wind speeds 
will slow down after noon...and then reach near 20 knots again 
around sunrise on Saturday.


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