Hurricane and Tropical Cyclones


Tropical Weather Discussion

axpz20 knhc 240238

Tropical weather discussion                                     
NWS National Hurricane Center Miami FL                         
0405 UTC sun may 24 2015

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 0000 UTC surface analysis and satellite imagery through 
0300 UTC. 

...Special features... 

Broad cyclonic circulation is analyzed as a 1008 mb surface low 
near 11n129w. Scattered moderate convection was within 90 nm NE 
semicircle of this low. The pressure gradient between this low 
the subtropical ridge to the N is maintaining NE to E 20 to 25 kt 
winds within 240 nm NW quadrant of the low. An earlier altimeter 
satellite pass indicated seas to 9 ft as well. The low has the 
potential to become a tropical cyclone as it moves N-NW to near 
12n132w sun and near 14n135w Mon. 

A 1008 mb low is analyzed at 05n139w with scattered moderate to 
strong convection observed within 75 nm se semicircle where  
winds are believed to be a fresh to occasionally strong breeze 
based on an earlier scatterometer satellite pass. There is some 
potential for tropical cyclone formation as the low reaches near 
06n139w sun and near 08n140w Mon. By Tue...numerical guidance 
suggests this low will weaken as the low pressure system to its 
east intensifies.

...Tropical waves...

A tropical wave was analyzed near 95w from the Guatemala coast 
to near the galapagos islands. Scattered moderate to strong 
convection was observed near the axis from 04n to 09n between 
87w and 97w. This wave is forecast to continue W around 10-15 kt 
over the next few days.

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

the ITCZ was analyzed from 06n100w to 09n110w...and 08n115w to 
10n125w. Scattered moderate to isolated strong convection was 
within 210 nm N of the axis between 110w and 120w.


N of 15n E of 120w...1030 mb high pressure centered well N of 
the area near 44n135w extends a ridge axis through 30n135w to 
the islas revillagigedo. This ridge is expected to remain 
quasistationary to early next week. On the eastern side of the 
ridge...recent ship observations and earlier scatterometer data 
indicated moderate to fresh NW winds along the Baja Coast 
between Cabo San Lazaro and Punta eugenia. The GFS indicates 
this may pulse to 25 kt overnight...repeating a trend from last 
night. An earlier altimeter pass noted seas to 7 ft...likely 
supported by SW swell in addition to shorter period NW wind 
flow. These combined seas will increase slightly tonight as 
winds pulse higher along the coast. The pressure gradient will 
weaken sun as deep layered low pressure over the SW United 
States shifts eastward. This will diminish the winds. Meanwhile 
a few thunderstorms were noted earlier over southern Baja 
Peninsula and adjacent waters including the southern Gulf of 
California related to jet dynamics aloft ahead of an approaching 
upper trough. 4-6 ft seas in south-southwesterly swell of 17-19 
second period has reached the entire Pacific coast S of Cabo 
lazaro in Baja California sur. These long period swells will 
subside over the next two days...but will still generate large 
and dangerous surf conditions along the coastline through the 

S of 15n E of 110w...the pressure gradient between ridging over 
the NW Caribbean and troughing to the SW enhanced by the 
aforementioned tropical wave has generated 20-25 kt winds in the 
Gulf of papagayo this morning with the help of nocturnal 
drainage flow. Seas have built to 8 ft. Enhanced seas will 
propagate W and mix with long period cross-equatorial SW swell 
across the Pacific waters from 09-12n between 90-96w this 
evening and subside to 5-7 ft tonight. Another weaker pulse of 
fresh to strong winds is expected in the Gulf of papagayo Sun 
night during the period of peak nocturnal drainage flow. 

Elsewhere...aside from the two low pressure system mentioned 
above...primarily moderate to fresh trade winds lie SW of the 
ridge axis. An earlier rapidscat satellite pass indicated fresh 
SW flow on the SW side of the ridge near 23n135w...between the 
ridge...part of a confluent area of winds flowing into a well 
developed low pres area near 33n150w. A cold front associated 
with the low pres will approach the waters along 140w between 
20n and 30n by early sun before stalling and dissipating Mon as 
the supporting low pres lifts NE of the area. The main marine 
impact will be continued fresh SW flow with seas to 9 ft in the 
area N of 25n W of 135w through Sunday.


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