Hurricane and Tropical Cyclones


Tropical Weather Discussion

axpz20 knhc 211624

Tropical weather discussion                                    
NWS National Hurricane Center Miami FL                         
1605 UTC sun Dec 21 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 1200 UTC surface analysis and satellite imagery through 
1500 UTC. 

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

the monsoon trough axis extends from 7n78w to 07n84w to 05n91w 
to 06n96w. The ITCZ axis extends from 06n96w to 08n102w to 
08n106w to 06n110w to 06n120w to 07n130w to 08n140w. A surface 
trough is in the ITCZ along 13n106w 09n107w 04n108w. Convective 
precipitation...scattered moderate to isolated strong within 30 
nm on either side of 07n79w 06n80w 04n81w and 4n110w 5n112w 
6n113w...from 07n to 08n between 95w and 96w...from 06n to 07n 
between 112w and 115w...and from 06n to 09n between 125w and 
140w. Isolated moderate from 07n to 14n between 101w and 111w.   


Long period NW swell continues to propagate se-E across the 
entire open waters waters N of the ITCZ W of 112w resulting in 
combined seas of 8-14 ft...with the highest seas near 28n120w. 
This long period NW swell has now arrived along the Pacific 
coast of Baja California norte...from 26n northward from 117w 
eastward...where winds are also NW-N at 20-25 kt as sampled by a 
recent ascat scatterometer pass. Expect 7-10 ft seas spreading 
southward along Baja California sur through the rest of today. 
The swells will then subside with 5-8 ft conditions expected 
along the entire Pacific coast of the Baja Peninsula on Mon and 
Mon night...and 4-7 ft seas expected on Tue across the coastal 
waters S of 28n. 

Model guidance is suggesting that northerly flow will increase 
to 20-25 kt N of 27n between 120w and 126w by 24 hours where 
seas will also be 11-13 ft...diminishing Tue. NE winds at 20-25 
kt will bleed through Baja California norte passes starting 
Tue...spreading SW to near 27n116w by early Wed before 
diminishing to 15 kt late Wed.

A 1030 mb high pressure is near 33n132w. A ridge extends from 
the high center to 20n110w. Northeast 15-20 kt trade winds are 
observed across the tropics between the ITCZ and the ridging 
with an area of embedded 20-25 kt NE winds and 9-14 ft seas 
across the W central waters from 07n to 22n W of 120w. The ECMWF 
model...the UKMET model...and the GFS model maintain at least 20 
to 25 knot wind speeds during the next 48 hours in the area from 
07n to 22n from 120w westward...with some intermittent periods 
of 25 to 30 knots. The pressure gradient is forecast to relax 
gradually relax after 48 hours. The wind speeds will diminish to 
20 kt or less across the discussion waters after 48 hours...with 
more tranquil conditions persisting through Friday. The combined 
seas will continue to subside to the 6-9 ft range across the 
Pacific waters W of 115w by Thu. 

The Gulf of California...NW-N 15-20 kt winds are expected through 
Mon night. The pressure gradient will tighten across the region 
early Tue with the NW flow increasing to 20-25 kt across the 
northern Gulf waters Tue morning...and 20-30 kt conditions 
spreading S across the entire Gulf of California by Tue evening. 
Seas will build to 10-11 ft in long fetch waters near 28n by Tue 
evening. The gradient will relax on Wed with 15-20 kt flow on 
Wed night and only 10-15 kt NW flow on Thu with winds becoming 
southerly at 5-10 kt Thu night through early Fri.

The Gulf of Tehuantepec...the latest rapidscat scatterometer 
pass during the late night and early morning hours consisted of  
fresh northerly winds in the Gulf area. The latest rap and GFS 
model guidance shows winds at fresh to strong levels only during 
the morning and afternoon of today. A strong cold front will 
blast into the southwestern corner of the Gulf of Mexico on 
Wednesday. Strong high pressure will push into southeastern 
Mexico. Northerly winds will surge through the chivela pass 
increasing to gale force Wednesday afternoon. The wind speeds 
will increase to near storm strength late on Wednesday night. 
Expect the gale event to end by Friday morning.

Gulf of papagayo...the UKMET and GFS show northeast winds 20 to 
25 knots only during the mornings and afternoons for the 48 
hours. Model guidance after 48 hours indicates a significant 20-
30 kt gap wind event on Thu night through Fri afternoon 
extending as far SW as 08n93w.


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