July 13, 2005
13 July 10am
Tropical Storm Emily is not necessarily a feature of concern unless NHC tasks aircraft.
Information on this system is available from NHC updates.
The system to the west of Central America yesterday is moving westward an is
unreachable from San Jose.
The main area of interest is the wave that was approaching Central America. There was a
large area of convection associated with this system just east of Nicaragua, likely spurred
by the interaction of the wave with an upper cold low. The low seems to have weakened,
and with it, the wave has lost almost all of its convection. Still, the wave is analyzed over
Nicaragua and may reflare as it enters the Pacific Ocean. Since this is the only game in
town, the P-3s were put on the hook to examine this system during the next few days.
Here's some notes from last night's conference call...
A tropical wave over the EPAC had moved to around ~100 W. Convection had flared on
either side of the wave axis, and a small low-mid level circulation was evident near 10 N.
However, the thunderstorm tops were being massively sheared from the east aloft; and
development was not likely to be imminent in this hostile environment. Also, since it had
moved this far west, it was ruled out as a genesis mission candidate.
The main focus remained to be a wave oriented NNW-SSE along about 85-86 W from
the NW Caribbean northeast of Honduras through Nicaragua and western Costa Rica to
the tropical East Pacific. This is the same system Sim has been mentioning the past
couple of days and is of interest for potential P-3 genesis missions. Some strong
convection associated with the wave was mainly present on the east side of the wave axis,
particularly over and to the east of Nicaragua and Honduras, during the afternoon and
early evening; it was enhanced by upper-level diffluence along a shear axis running to the
northeast. There was also some semblance of an outflow boundary propagating
westward over part of Central America along the wave axis. No other coherent
convective patterns were present though, and the CIMMS 850 mb vorticity analysis only
showed an amorphous glob of weak positive vorticity in the SW Caribbean and another
zonal lobe oriented at about 11.5 N and stretching from about 86-88W in the EPAC.
An upper-low that had been interacting with the wave, but the low had opened up and
become an inverted trough axis that was present over the EPAC from Guatemala
southward along ~88 W. A large, hefty mid-upper level ridge remained firmly in place to
the north, with a zonal ridge axis stretching along 26 N from the Bahamas to
Brownsville, TX and then down WSW to south of the Baja peninsula. While the shear
reamined low right along and to the east of the wave according to the CIMMS analysis, it
became quite high out of the ENE just offshore the Central American
Pacific coast. With the ridge forecasted to shift slowly southwestward over the next 72 h
according to the 18Z GFS run, the shear was not likely to abate soon. The wave appeared
to be moving about 4-5 deg. lon/day westward and would mostly be offshore into the
EPAC by today. The 12Z NOGAPS and the 18Z GFS runs showed a system developing
from the wave but not until 4-4.5 days down the road (thanks for the data, Sim). It would
be past 100 W by that point and could only be reached from Acapulco.
Although missions in Emily were ruled out, we briefly touched on the intensifying
tropical storm that was moving near the Windward Islands. After having moved quickly
westward and even a bit south of due west, the storm finally had a slight northward
component, and was moving towards 275 deg. in the 21Z NHC advisory. Explosive
convection had begun generally to the south of the analyzed center around 18Z and was
continuing still six hours later, in which a 350 km wide CDO had formed. A strong
squall line had propagated from the TC northwestward earlier in the day but had rapidly
moved far enough away to the NW to just south of Puerto Rico and the Virgin Islands so
that it no longer had any effect of choking off moist low-level inflow. As shown in the
GOES WV imagery, surrounding dry air that previously limited intensification was
nearly gone. Also, the shear was very low, as stated in the SHIPS file, and the storm had
attained a symmetrical shape. All the track model guidance, except for the UKMET,
showed a WNW track through the Caribbean over the next 4-5 days. With SSTs over
29C and shear expected to stay low, the system could intensify so long as it gained just a
little bit of latitude northward, so that it could avoid the disruptive effects of South
American terrain cutting off inflow on the southern side.
July 14, 2005
14 July 8am
Tropical Storm Emily is not necessarily a feature of concern unless NHC tasks aircraft.
Information on this system is available from NHC updates.
The main area of interest continues to be the wave that just entering the Eastern Pacific.
Convections is spotty, though there are two regions of deep convection, one in the Gulf
of Tehuantepec, and another comma-shaped feature to the southeast. Both systems
appear to be weakening as the diurnal cycle wears on.
TAFB continues to identify this region as a tropical wave. It is on the eastern edge of
low-level westerlies along about 10N. The models suggest that 850-mb vortmaxes
advected in the westerly flow approach the 700-mb vortmax associated with the wave
and get wrapped in, spurring cyclogenesis. As a result, the P-3s will likely sample the
region to the south where these low-level features are supposed to be, and the region
further north associated with the tropical wave. Tropical Storm Emily is still on our
radar, but not for immediate consideration for TCSP planning. NHC P3 tasking is likely
on the horizon for Emily, but until this happens, the EPAC will be the focus.
A tropical wave is located over Central America along ~88 W and has been kicking off
convection in the region. This, along with a little extra lift provided by the local land
breeze front, has resulted in an extensive area of cloudiness along the western Central
American coastline. NOAA 43 is currently flying a convective area on the west side of
this wave (~12N 93W) and dropsondes are showing 10-15 kt westerlies from 700 mb to
the Sfc all around the area of interest. Shear in this region is high (~20-30 kt) and much
of the convection in this region has been weak and transient. The global models also
seem less impressed with genesis, with some hints of a weak system forming in 60 hr
(UKMET) and as far out as 96-120 hr (NOGAPS and GFS).
NOAA 42 will likely be on the hook for a follow-on flight tomorrow morning and
NOAA 43 may be for tomorrow evening. However, the area of interest may not be all
that interesting for much longer.
July 15, 2005
15 July 8:30am
Tropical Storm Emily is not necessarily a feature of concern unless NHC tasks aircraft.
Information on this system is available from NHC updates.
The tropical wave in the Eastern Caribbean has continued to move west to about 93W.
However, convection has flared up overnight in a line alone about 10N, likely the ITCZ.
There are numerous vortices embedded within this convection moving westward, most
prominently just off the coast of Costa Rica.
The models are now more consistently developing a system in the Eastern Pacific in the
next 48 h. The models seemed to change quite a bit with the assimilation of the
dropwindsonde data from the previous day. Regardless, this will be a great dataset for
study of the impact of tropical convection on midlatitude weather.
Return to IFEX calendar page