Recent Seeding missions

July 2008

July for the most part was pretty dry for most locations across the target area.  However, the saving grace for the month was Hurricane Dolly that made landfall near Brownsville on the 24th.  The rainfall totals for the month below reflect this as Laredo received the most rainfall in the target area with less amounts as you go northward.  Most locations in the eastern and southeastern parts of the target area were above normal for the month while the northern and western parts of the target area were a bit below normal for the month.  We are at the half way point of the year and precipitation wise, most locations are anywhere from 3 to 8 inches below normal.  There are only a few places at normal across LaSalle and Webb counties.  The image below shows total precipitation as of August 7, 2008 for the entire year.  As well, the next image shows the percent of normal.  Weather modification wise, a total of seven seeding flights took place on five seeding days.  As well two reconnaissance missions took place during the month of July.  All missions were classified as rain enhancement.  A total of 119 flares and 4,760g of AgI was dispensed during the month.

Below is a link to the flight activity spreadsheet for the month of July.

July flight activity

July 1

Convection started a little bit later today and convection was a little bit stronger but still pretty similar to yesterday.  A somewhat tropical atmosphere exists and convection at times seemed to be low topped.  Light showers existed before the later afternoon hours where convection started to from.  Convection was seeded in the STWMA target area and seemed to fair pretty well.  A mission was launched on these cells that were moving into Zavala County from McMullen County.  The convection seemed to continually do better than other convection around the area.  A total of 12 flares and 480g of Agl was dispensed.

July 2

As daytime heating started across the area, numerous scattered showers and thunderstorms occurred over the target area.  Convection started a bit earlier than it did yesterday, as the area is bit closer to the low and experiencing better dynamical lifting.  A seeding flight was launched with the onset of this activity which occurred in LaSalle, Dimmit, and Zavala counties.  Per radar trend, convection did not seem to last very long and was somewhat low topped during portions of the missions.  The convection that was seeded last seemed to fair the best, as heating might have been better later in the day. A total of 29 flares and 1160g of AgI was dispensed.

July 3

Weak echoes were developing in LaSalle and Webb counties during the early afternoon hours.  These storms did not take very long to reach seedable limits and therefore a seeding mission was launched into LaSalle County.  Convection continued to develop in Dimmit and Frio counties were seeding was done.  Seeding was done in Frio County because it was moving into the SWTREA target area and therefore would impact Zavala County.  As in pervious days, convection seemed to become unstable by late in the day, when bases would be to the surface and inflow was very hard to find.  A total of 33 flares and 1,320g of AgI was dispensed.

July 4

Convection was once again today was moving up from the Gulf of Mexico. Convection started out pretty low topped and the freezing level was very high due to the tropical atmosphere in place.  As the day went on however, tops became higher and seeding was then able to be done.  Seeding was done in the early afternoon hours across LaSalle County.  Convection was ongoing in other parts of the target area, but the best lift seemed to be in the southern/southeastern parts of the target area and thus convection was more robust here.  Another interesting note is that late morning convection did not have any lightning with it and only once heating got going did the storms start to produce lightning.  A total of 27 flares and 1080g AgI was dispensed.

July 20

A weak upper level low was located jus to the west of Del Rio.  A shortwave moved around the low across the target area during the evening hours.  Convection formed with dynamics from the shortwave and daytime heating.  Two missions took place in Dimmit, LaSalle, and Zavala counties.  Scattered showers and thunderstorms occurred during the missions and no real organized convection ever materialized.  A total of 18 flares and 720g of AgI was dispensed.

May 2008

May  brought forth renewed rain chances for the area.  However, rainfall was still well below normal for the year and drought conditions persisted.  The first part of the month was actually pretty slow cloud seeding wise and the most activity took place during the middle of the month.   Most areas across the target area received between 2 to 3 inches of rain on average but the wet spots were southern LaSalle, Central Dimmit, and central Webb counties.  Most of southwestern Texas received adequate rainfall this month compared to locations further to the east where spots of 8 inches below normal were recorded for the month.

As far as flights went for the month, there were definitely less flights this year compared to what usually happens in May.  May is usually one of the two busiest months in southwest Texas.  High pressure that built in during the second week and during the last week of the month hampered seeding flights dramatically.  Two months out of the week, hot and dry conditions prevailed.  A total of five seeding flights occur on four seeding days.  One reconnaissance mission took place midway through the month.  Of the five flights that took place, three were classified as rain enhancement and the other two were classified as hail suppression.  For the month of May, 144(40g) flares and 5,760g of AgI was used.  Below is the monthly rainfall totals for the target area and the flight activity spreadsheet for the month.

May 2008 flight activity

May 14

During the afternoon hours, the atmosphere became increasingly unstable with the approach of mid level dynamics across West Texas and into Mexico.  The event started with a very strong supercell moving out of Mexico into Maverick County.  As this supercell came closer to the border, a hail suppression mission was launched on the first cell.  Hail suppression was terminated when the pilot noted rotation and a lower of the base.  Further more, soon after this observation, a tornado warning was issued for this cell.  Two more supercells, following almost the exact track as the first one were moving out of Mexico.  The pilot was instructed to move to the border and wait for the supercell to cross the border.  As the cell moved into Maverick County, a hail suppression mission commenced and seeding was conducted.  The pilot informed the meteorologist that he was low on flares, so the pilot landed.  Yet another cell moved into the area and after a small amount of time on the ground, another hail suppression mission commenced in Zavala County during the evening hours.  A total of two flights took place and all missions were classified as hail suppression.

May 15

Convection started to move into Mavierck County from Mexico during the late evening hours.  The leading edge of the complex of storms coming out of Mexico seemed to be the most seedable due to the extensive area of cloudiness behind it, with embedded showers and thunderstorms.  A pilot was launched on the convection as it moved into Texas. A hail suppression mission took place in Maverick County as convection was expected to drift into the target area.  About half way through the mission, bases were starting to become broken and ragged, so seeding activities were administered quickly.  After a considerable amount of material was put into the cloud, the mission was concluded. 

May 21

During the afternoon hours, some weak showers did manage to occur with the approached of the aforementioned low and a weak shortwave ejecting on the southeast side of it.  A mission was launched during the late afternoon hours.  TITAN was showing decent convection but pilot reported almost nothing when encountering the cell that he was sent to.  He only reported a light shower with hardly any bases.  The pilot investigated the storm, but no inflow was found. 

By the evening hours, an explosive development of convection  took place in LaSalle and Dimmit counties.  A mission was launched immediately and seeding commenced soon after.  Inflow during the mission was very hard to find, but when it was found, very high inflow values were detected.  The pilot reported having to do a lot of maneuvering and areas of inflow when found were very small.

April 2008

A very dry winter across the target area continued to evolve into a dry spring.  Most locations across the target area for the month of April were about one to two inches below normal.  However, there were isolated areas in the target area that received higher amounts of rainfall during the month.  Central Dimmit and central and eastern LaSalle counties proved to be the big winners for month with 3-4 inches of rain.  The drier parts of the target area were in central Uvalde County and central Zavala County.  Uvalde and Zavala counties were also 1 to 2 inches below normal for 2008.  The wet spots for 2008 were in central Dimmit and LaSalle counties.  Most of the rainfall for 2008 came this month, with very little rainfall falling between a January to March timeframe.

Weather modification wise, flight activity was at about normal for this time of year.  This was a welcomed sight as no missions were flown during the month of March. A total of five missions occurred on four seeding days.   Of the five missions that occurred, one was classified as rain enhancement and four were classified as hail suppression.   For the month of April, a total of 137(40g) BIP Flares and 5,360g of AgI was used.  Below is a spreadsheet for flight activity for the month of April.  As well rainfall totals from towns around the target area.

April 2008 flight activity

April 17

An upper level trough just north of the area was moving a shortwave across the region during the evening into overnight hours.  A cold front as well was northwest of the area and a dry line ahead of the front.  A broken squall line was moving from the northwest along the dryline during the evening hours.  As cells approached the target area, they seemed to intensify.  A seeding mission was launched in Uvalde County before the line entered the target area.  Soon after, thunderstorm warnings began to occur with these storms.  Vertical cross sections of the cells on TITAN showed higher reflectivity's in the upper parts of the cloud.  With these last two things being said, a hail suppression mission commenced.  Pilot reported frequent lightning throughout the mission.  As the line moved into the target area, it solidified into a solid line.  After operations has commence and a bit of time had pasted, the higher reflectivity's seemed to come down.  Hail suppression operations continued until visibility reported by the pilot was almost zero.  At this point, the mission was concluded due to visibility and safety issues.  This mission took place during the evening hours over Uvalde and Zavala counties with 45 flares and 1800g of AgI.

April 23

Convection began to fire during the evening hours across the border along the Mexican mountains.  This convection formed due to good surface heating along with orographics off the mountains.  Convection was able to move off the mountains with the help of a mid level disturbance moving across northeastern Mexico.  A pretty solid line evolved as it moved closer to the Mexican/Texas border.   A seeding flight, more specifically a hail suppression mission was launched soon after the convection crossed the border.  Pilot reported light to moderate rain throughout the early parts of the mission.  The pilot also reported increased turbulence and frequent embedded lighting.  Seeding continued for some time and inflows near the end part of the missions were tapering off and becoming harder and harder to find.  Near the end of the missions, the convection came to an almost complete stop over southern Maverick County.  Seeding concluded as the intensity decreased and the severe thunderstorm warning expired at 10pm.  This mission took place in Maverick county during the evening hours using a total of 20 flares and 800g of AgI.

April 25-26

A cold front was moving into the target area during the evening into the overnight hours.  A squall line accompanied this cold front and severe warnings were constant with this feature as it moved further south/southeast into the target area.  Hail suppression activities were conducted during these flights.   Seeding commenced but visibility was an issue during the first half of the first flight.  Pilot reported frequent lightening and moderate turbulence during the first part of the first flight.  After a suitable amount of material was used for hail suppression purposes, the pilot returned to base.  However, ongoing convection in Kinney County continued to maintain its intensity and this convection was continually severe.  A second flight was launched as the frontal boundary was located across the SWTREA target area.  The strongest convection that was in Kinney County earlier had moved south into Northern Maverick County and was continuing to move closer to the SWTREA target area with a  slight easterly component.  Felt that visibility might be an issue due to the prevalence of status, but decided to launch a mission and try anyway.  The second flight was hail suppression.  Visibility was poor to begin with but seeding did commence as the pilot was able to find higher ceilings.  the first mission took place over Kinney and Uvalde counties during the evening hours with a total of 29 flares and 1160g of AgI.  The second mission took place over Dimmit and Zavala counties using a total of 37 flares and 1480g of AgI.

April 27

During the afternoon hours, weak showers and a few isolated thunderstorms formed across the target area.  A mission was launched mainly for reconnaissance issues due to the fact that the mostly cloudy conditions were prevailing and thunderstorms that did develop seemed to be elevated.  The pilot reported good visibility despite cloud cover during the missions.  Inflow was marginal and seeding was done on a very small, isolated thunderstorms.  This rain enhancement mission took place over LaSalle County during the early afternoon hours using 7 flares and 280g of AgI.