weather, weather safety/preparedness

More Naples, FL area wildfires (H. Michael Mogil, CCM, CBM, NWA-DS*)

Late Thursday, Apr. 20, 2017, two wildfires of unknown origin broke out in the Golden Gate Estates area of east Naples, FL. Although fire fighters jumped into action quickly, dry and windy conditions allowed the fire to spread. By this morning, the combined blazes had grown to about 2,500 acres.

Collier County Emergency Management issued evacuation orders for some limited areas yesterday and expanded areas affected during today. As of late this afternoon, the boundaries of the evacuation area extended from the south side of Golden Gate Boulevard south to the east-west portion of I-75 and from Collier Boulevard east to Wilson Boulevard.

Jim Dickey, WZVN-TV (CH 7 – ABC, Fort Myers) Certified Broadcast Meteorologist, posted radar imagery at around 10:00 a.m. E.D.T. today of the dual fires at his Twitter page (@WxDockey). Dickey noted that “Now that A.M. inversion has lifted, smoke plumes from #30thStFire and #FrangipaniFire visible on radar” (Fig. 1).

     Images from the Immokalee Fire Control District showed the scope of the fires and their associated large billowing smoke clouds (Fig.2 and Fig. 3). Overnight and during Friday morning, the smoke reached the Naples City limits, lowering visibility at the Naples Airport (KAPF) to 3 miles. Based on the trajectory of the plume this morning (WZVN-TV radar imagery and video), and the fact that the smoke plume is still showing up on the Miami National Weather Service radar late this afternoon, most of western Collier County (including the city of Naples) and parts of southern Lee County are going to be experiencing smoky conditions through tonight and into early Saturday morning.

Thus, smoke from the fire will be affecting many more people than the fire itself. Small airborne particles from the fire may lead to respiratory problems, even for healthy people. Check out Fig. 4, a wildfire poster from http://www.ready.gov, republished by Florida Health. It contains some useful tips for dealing with smoky air.

© 2017 H. Michael Mogil

Originally posted 4/21/17

* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.

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SWFL-GWCC South Florida’s Cowbell fire grows rapidly (H. Michael Mogil, CCM, CBM, NWA-DS*)

Discovered on Mar. 30, a relatively small brush fire in South Florida’s Big Cypress National Preserve (eastern Collier County) grew slowly during the following week. By Apr. 8, the Cow Bell fire (so named, because it is near the Cow Bell Strand within the Big Cypress National Park – Fig. 1) had consumed roughly 600 acres. On Sun., Apr. 9, thanks to an increase in easterly winds (and continued dry weather), the blaze exploded. By late Sunday, the blaze had consumed more than 8,000 acres. For comparison, this fire is slightly larger than the burned acreage from the Picayune Strand Fire (western Collier County) back in early- to mid-March. Fig. 2 shows the smoke plume from just north of the Cow Bell fire area.

During much of its lifetime, the fire has been moving westward across “Alligator Alley,” mostly parallel to Interstate Highway (I-75). Campgrounds in the Bear Island area, within the Preserve, are being evacuated. Due to the rapid spread of the fire, fire-fighting crews have had to reassess possible containment lines for stopping the fire’s westward movement.

Maximum smoke impacts were expected closest to the fire, with smoke also impacting I-75 between mile markers 55 through 80. On the evenings of Apr. 9 and 10, around sunset, smoke smell permeated the air in parts of North Naples (more than 50 miles from the fire). Smoke from the fire was also evident in the skies over North Naples. Fig. 3 shows the smoke plume as shown on the NWS Miami radar during mid-afternoon on Apr. 9.

Lacking any rainfall for the foreseeable future, and given the pineland and cypress habitat that is ablaze, the hundreds of fire-fighters engaged in battling the fire will have their hands full. Fortunately, there are only a few structures anywhere near the fire area, at this time.

Officials have urged all drivers on I-75 to use extreme caution and to check road conditions before starting travel across the “Alley.” The highest likelihood for experiencing roadway visibility restrictions due to smoke will be between 4:00 a.m. and 8:00 a.m. daily. This is the time window during which an inversion, a low-level temperature pattern with warmer air overlying cooler air, is most likely to trap smoke near the ground.

Big Cypress National Preserve officials have instituted the following closures:

  • Gator Head Campground
  • Bear Island Campground
  • Jeep Campground
  • The road leading into the Sanctuary except to residents
  • All trails between state road 29 and L-28 Canal including the Florida Trail
  • All public lands west of the L-28 Canal
  • All public lands east of state road 29
  • All public lands south of the Preserve boundary
  • All public lands north of Alligator Alley

In addition, a temporary flight restriction has been placed over the Cowbell Fire (ground level to 3,000 feet mean sea level) to provide a safe environment for fire-fighting aviation operations. In addition to 17 fire engines, at least seven helicopters and two water tanker aircraft are involved in firefighting efforts. The area will likely be expanded to accommodate increased fire growth.

© 2017 H. Michael Mogil

Originally posted 4/11/17

* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.

 

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Description of the four-panel GWCC home page display (H. Michael Mogil, CCM, CBM, NWA-DS*)

The GWCC home page contains a four-panel graphic containing satellite and radar observations and a severe weather outlook (all from NOAA). The following is a brief overview of these graphics (organized by column from left to right):

  • GOES Enhanced Infrared satellite image (upper left) – This image, obtained by a GOES (Geostationary Operational Environmental Satellite) measures the “heat” given off by clouds, large water bodies, land surfaces, and clouds. Using a special “enhancement” scale (see color bar at the bottom of the image, just below the NOAA logo), warmer colors appear as blues and greens and colder temperatures appear as yellows and reds. Note, that GOES satellite images on different web pages (or in different GWCC posts) may use different enhancement or “false color” image temperature scales. Colorized images, such as these, should always have their own color key.
  • GOES Water Vapor satellite image (lower left) – This geostationary satellite image also measures “heat,” but the satellite sensors used are more sensitive to the amount and distribution of atmospheric water vapor. When the atmosphere at the middle and high altitudes is dry, infrared energy from lower altitudes (where temperatures are normally warmer) is able to escape to space and be detected by the GOES (Geostationary Operational Environmental Satellite) sensors. This image has been false-colored using a special “enhancement” scale: dry (black and orange), mid- and high-level moisture (white), and cloud-laden at mid- and high-levels (blue and green through red and purple).
  • Storm Prediction Center (SPC) convective outlook (upper right) – SPC issues a wide array of severe weather and other thunderstorm-related guidance and outlook products. They also issue tornado and severe thunderstorm watches and fire weather outlooks. This image, which is often updated several times a day, shows expected thunderstorm and severe thunderstorm activity for “Day 1.” “Day 1” extends from the forecast time until the next 1200 GMT (Greenwich Mean Time or 8:00 a.m. E.D.T / 7:00 a.m. E.S.T. Favored areas for thunderstorm / severe thunderstorm activity are depicted as, “to the right of a line,” as shown by an arrow at the end of any line.
  • National radar composite image (lower right) – This image brings together radar reflectivity data from some 100 plus radar sites throughout the contiguous 48 states. Radars measure how much energy atmospheric solids and liquids (hydrometeors such as snow, hail, and rain, as well as particles such as dense smoke and volcanic ash) reflect back to a radar site. The greater the reflectivity value (shown in dBz units), the greater the concentration of so-called “hydrometeors,” solids and other objects (e.g., birds, bats), the radar beam may intercept. The color scale ranges from blues and greens (the lowest reflectivities) to reds and purples (the highest reflectivities).

© 2017 H. Michael Mogil

Originally posted 4/7/17

* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.

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Heavy rainfall gradients and rainfall rates (H. Michael Mogil, CCM, CBM, NWA-DS*)

Across Louisiana, Mississippi and parts of far East Texas, torrential rainfall occurred Sunday and Sunday night. Widespread one to four inch rainfall amounts were reported, with some locations noting amounts of six, eight and even ten inches (Fig. 1). Alexandria, LA, in the west-central part of the state, reported more than nine inches over a nearly 12-hour period, with nearly continuous thunderstorm activity for a roughly 8-hour period (Fig. 2).

By early Tuesday, the large-scale storm system responsible for the storminess has moved well to the northeast and the heaviest rainfall had moved well to the east of The Pelican State. In the wake of the Sunday rainfall activity, flood warnings remain in effect for many areas in Louisiana that received excessive rainfall or are downstream from these areas (Fig. 3).

Two things are striking in Fig. 2. First, there are numerous bands of heavy rainfall aligned southwest-to-northeast. These mark the locations in which thunderstorm lines became at least somewhat stationary. Then thunderstorms, moving along the line, dumped successive bursts of heavy rainfall. This scenario, in which numerous storms move across the same area, is known as “training.”

The second thing of note is the large precipitation gradients in areas near the heaviest rainfall. One only needed to have traveled a relatively short distance to go from eight to ten inches of rainfall to amounts of around an inch.

A similar, albeit greater, rainfall gradient occurred in my backyard, Collier County, in southwest Florida, on Sunday. A small convective weather system (without thunder and lightning), developed along the sea breeze front and moved slowly northwestward across parts of north-central Collier County. Heavy rainfall (between 1.47 and 1.78 inches according to two nearly co-located reporting stations) fell just two miles to the northeast of my rain gauge. According to a high school student interested in meteorology (and one

who attended a Naples weather camp last summer), most of the rainfall that he measured fell in just under 20 minutes (Fig. 4). That translates to an hourly rainfall rate of 4.5 inches to 5.5 inches. I measured a scant 0.07 inches of rainfall, although I did briefly experience gusty outflow winds from the convective weather system. Fig. 5 shows radar-based rainfall estimates for southwest Florida on Sunday.

While these situations were somewhat similar in their excessive rainfall and localized rainfall gradients, one was linked to a large-scale low-pressure system and the other to a small-scale sea breeze zone. This is testimony that different meteorological scenarios can yield similar meteorological outcomes.

© 2017 H. Michael Mogil

Originally posted 4/4/17

* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.