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IFEX Forecast summaries

July 4, 2005

Three systems were being considered: TD4E around 15N, 100W just south of Acapulco; TD3 around 20N, 88W over the Yucatan peninsula; and a strong wave at 60W. TD4E (pre-Dora) was too far west for operations and had already undergone genesis. TD3 (pre- Cindy) was uncertain as to whether it would decay over the peninsula or reform north of the peninsula. The latter scenario would put it too far north for operations on the 5th. The wave at 60W looked promising for development, but was too far east for operations. We debated whether a vort max at 10N, 78W was a wave or a stationary feature. Likely plans were to fly a test mission on the 5th along the south end of the wave that produced TD3 - currently along 90W. While this wave was convectively active, it is in a high easterly shear zone and not likely to develop.

July 6, 2005

July 6th am discussion
3 tropical systems of interest - TS Cindy has made landfall over LA and is weakening as it moves northeast; ex-TD Dora is winding down near 18N, 108W over cooler waters; and TS Dennis near 15N, 71W moving WNW and intensifying. Cindy and Dora are not possibilities, nor is a moderately convective wave near 100W. Dennis is progged by all major models to continue WNW for 72 hr, then turn to the NW and NNW. Dennis' track will take it close to western Haiti and Jamaica (and may cause some difficulties flying full tracks in Dennis on Thursday), over western/central Cuba late Friday night, then landfall between LA and the Florida peninsula late Sunday night/early Monday morning. All models are tightly clustered currently. For intensity, all factors in SHIPS (shear, SST, OHC, RH, vorticity, convection, divergence) are suggesting intensification. The chance for RI (>= 25 kt) is 24% (double climo). Everything suggests Dennis will be a major hurricane within 60 hr, if not sooner (maybe by Thursday night).

July 7, 2005

July 7th am discussion
Only game in town is hurricane Dennis for flights in the next 3-4 days as other waves are too distant. Dennis is strengthening Cat 2 hurricane with winds 90 kt and pressure 968 mb. It is moving NW about 9 kt, but a slightly faster movement toward WNW is anticipated during the day. All factors for intensification look conducive (warm deep water, moist unstable air) though the analyzed shear in SHIPS (~14 kt) looks higher than what it may be. System should reach major hurricane status by tonight. Only inhibiting factor could be influence of land Jamaica (possibly, but more likely to skirt the coast) and Cuba late Friday. Tracks have been consistently taking the hurricane between the gap of Jamaica and Cuba around 00Z tonight, then landfall south of Havana on the afternoon of Friday, with landfall late on Sunday somewhere between MS and Florida panhandle. For tonight's flights taking off around 03Z, the main logistical problems will be closeness to land for both Jamaica and Cuba which will limit the flight tracks some.

Notes from the 6 p.m. EDT conference call...
Dennis continues to be the only system of interest at this time...we seem to be kind of in a August-September HFP mode right now! Anyways, the storm had continued to intensify during the day and recon aircraft found it deepening at a rate about one mb per hour all afternoon. By 21Z, the storm had already made it to major hurricane status as a Cat 3 with 100 kt winds, and by 22Z the central pressure was down to 956 mb. The inner core was very tight with a small eye depicted on both the VIS and IR imagery. There was evidence that it was going through a concentric eyewall cycle in the late afternoon, as the central diameter had contracted to 9 n.m. in the 20Z fix and then back out to 15 n.m. in the 2130Z fix. Also, evident in the IR imagery was an eyewall wavenumber-2 asymmetry.

The storm had definitely turned to the NW during the afternoon, going north of Jamaica, and was headed towards Cabo Cruz, Cuba. The forward motion appeared to be 13-15 kt. The shear, as depicted from CIMMS was low; SHIPS had diagnosed it from the NNW at 15 kt at 18 UTC. The SSTs were also around 29 C beneath the storm. An mid-upper level ridge still seemed held in place over eastern Florida, as depicted by the WV imagery and the 12Z rawinsondes from EYW and MIA (easterlies at all levels from the past four soundings). The 200 mb ridge axis appeared extended from about Daytona Beach WSW to about Clearwater and out into the Eastern Gulf.

Most of the forecast guidance was tightly clustered for the first 48 h, showing the storm continuing to move NW, making multiple landfalls over SE and Central Cuba, and then passing west of to very close to Key West Saturday morning. After that, there was hints of the storm responding to a shortwave dropping out of the Tennessee Valley and moving more NNW, making landfall along the Gulf Coast Sunday morning to evening anywhere from Mobile, AL to east of Apalachicola. The outliers were the UKMET, taking the storm NW to the central LA coast, and the CMC (Canadian), taking the storm northward up the FL West Coast. The official NHC forecast was in the middle of the pack. During our discussion, the new 18Z GFS came in and had the storm shifting back to the west after 36 h and making landfall around Pensacola in 72 h (the "windshield-wiper" effect). The 18Z run also went back to having the shortwave trough lift out before having a major impact on the storm. For potential operations with N43RF and the ER-2 on Saturday afternoon, we estimated the storm would be about 250-300 n.m. offshore Ft. Myers at 18Z, based on the 21Z official forecast and the new 18Z GFS run.

The future intensity was difficult to gauge. It all depended on how long Dennis would be over land and the type of terrain Dennis would encounter. If the storm was disrupted to a big extent, it might not quite make it back to major hurricane status; however, the futher west it tracked, the more likely it was to remain strong as it entered and traversed the Gulf. The 18Z SHIPS showed low shear up through landfall and SSTs along the official track to be at or above 28 C. The 18Z GFS depicted a strong anticylone over or just to the north of the storm the entire time.

July 8, 2005

Notes from the 8 p.m. EDT conference call...
The only game in town is Dennis, which will keep everyone busy for a few days until it makes landfall, likely in the Florida panhandle sometime Sunday afternoon. The forecast positions were provided. All other information is provided in the NHC discussions and forecasts.

July 9, 2005

Notes from the 8:30 p.m. EDT conference call...
Dennis is once again rapidly deepening, though it is interesting that it is doing so over a relatively cold eddy in the East-central Gulf. The models continue to be very consistent in forecasting a landfall near the Florida-Alabama border tomorrow afternoon. The main discussion was whether to task a second P-3 for an inland-decay mission. This was to be decided with discussions between the PIs, the field program director(s) and Jim McFadden. Else, the second P-3 will return to San Jose, though there is nothing in the region that might be interesting to fly in the near future.

July 10, 2005

Sunday, July 10th 8AM
Dennis and the wave at 40W were both discussed. Dennis is headed NNW at 13 kt, though it did take a northward jog that was not expected to continue. Landfall was anticipated between 3 and 6pm Eastern time today between the MS-AL line and just east of Pensacola. If Dennis did continue a more northward track, it would hit east of Pensacola closer to 3pm or so. Current intensity was 931 mb/125 kt and some fluctuations of it due to either eyewall dynamics and/or slightly less heat content shelf waters were possible. Tentative plan was to have 43 take off at 11am, followed by 42 at 3pm for landfall and post-landfall missions. The wave at 11N, 40W was also discussed for possible missions later on. It currently had only moderate shear (~10 kt) over it, SSTs about 28C and fairly strong circulation already. It could become a tropical cyclone in the near future and reach 60W in about 4 days.

July 11, 2005

11 July 10am
There are currently three areas of interest. Tropical Storm Emily is moving westward toward the Caribbean Sea. It is surrounded by dry air, possibly from the SAL, which may inhibit intensification, though it looks better in satellite than it did yesterday. The forecast is for it to follow the path of Dennis while strengthening moderately.

Two systems surround Central America. A complex area of disturbed weather is located between 92 and 100W. The western portion of this disturbance appears to be convection that moved off land into the Gulf of Tehuantepec overnight. The eastern portion is a squall line that moved across Costa Rica and Nicaragua last night, and is moving rapidly westward. TAFB is not identifying this system as a tropical wave. Shear is moderate over this region, but the upper-level high currently centered over the Eastern Gulf of Mexico is forecast to move southwestward and lessen the shear.

The system to the east of Central America is an area of deep convection east of Nicaragua that is the result of the interaction between a tropical wave and an upper low. These features are moving slowly westward, and little development of this system is likely at least until it gets into the eastern Pacific.

Of these, the first two will likely be out of range when flights can begin Thursday, which makes the last of the above disturbances the most interesting for operations in the near future.

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.

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