After a July with rainfall that was significantly above normal (Link), Tampa experienced heavy rain on both August 1st and August 3rd, leading to flooding conditions. The animation of Total Precipitable Water, above, from 2-4 August, shows the moisture-rich environment in which the showers and thunderstorms developed. Tampa appears to be in a corridor of moisture transport between tropical easterlies over the Atlantic and more westerly motion in advance of a surface trough that had sagged into the northern Gulf of Mexico. As a result of the rains (3.89″ on 1 August and 4.39″ on 3 August), Flood Warnings and Flood Watches persist on 4 August, and River Gauges (Source: http://water.weather.gov/ahps/index.php) continue to show conditions above flood stage (below).

GOES-13 Imagery, below, captured the evolution of the heavy rains on 1 August (Loop available here as mp4). These rains fell mostly during the day, and satellite data suggests training convection (that is, repeated development of thunderstorms over one region) produced the rain.

Visible imagery (Click here for mp4) during the day on 1 August (above) confirm the training nature of the convection over Tampa.

In contrast, the heavy rains early on 3 August were associated with a strong mesoscale convective system (loop shown below, or available here as mp4) that developed over the northeast Gulf of Mexico and then sagged southward over Tampa.

The toggle below of 11.45 µm Brightness Temperature and Day Night band visible (0.70 µm) imagery from 0751 UTC on 3 August shows very cold overshooting tops with temperatures as cold as -88 C over the northwest Gulf. Transverse banding around the periphery of the system is also apparent. Such bands are a signal of turbulence (although no reports were issued at that time).

How much rain has fallen in the week ending 4 August 2015? The image below, from this site, shows totals exceeding 10″ just north of Tampa.

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Strong thunderstorms developed over the upper midwest ahead of a cold front in the afternoon of 2 August 2015. Large Hail (up to 4.25″ diameter in Ogemaw County Michigan) fell and strong winds were observed (up to 70 mph in Portage County Wisconsin) over parts of eastern Wisconsin and lower Michigan. (SPC Storm Report). The visible animation from GOES-13, top (available here as an mp4), shows the development of the storms.

The destabilization of the atmosphere was captured well with the GOES Sounder depiction of Lifted Index, shown above. Values exceeding -10º C were common in the moist air feeding into the developing thunderstorms. The GOES-R Legacy Atmospheric Profile (LAP) Algorithm for 2 August similarly shows the strong instability around Lake Michigan. Lifted Indices also exceeded -10º C.

The GOES-R LAP Algorithm (and the GOES-Sounder) can also compute Convective Available Potential Energy. Values for the GOES Sounder are shown above (they are routinely available here); those for the GOES-R LAP Algorithm are below. The GOES-13 Sounder showed values approaching 5000 J/kg. Values from the GOES-R LAP Algorithm show values around 3000 J/kg. Note how the spatial extent of the instability in both CAPE and LI fields matches well in the Sounder and LAP fields.

The storms occurred on a day shortly after the Full Moon, so they were well-illuminated for the Suomi NPP Day Night Band imagery, shown below for 0751 UTC. The parallel lines of clouds over eastern Ohio and western Pennsylvania marks a wind-shift line as shown in this plot that includes surface observations. Those parallel lines of clouds were persistent, as they were present in the 0603 UTC Day Night Band imagery as well (Click here for a toggle between 0613 and 0751 UTC.)

The 11.45 µm Imagery from Suomi NPP shows evidence of overshooting tops persisting at night.

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A strong tornado (rated a high-end EF-2) touched down near Pierson, Manitoba at around 0130 UTC on 28 July or 8:30 pm local time on 27 July (Press Report) and persisted until about 0355 UTC or 10:55 pm local time (near Virden Manitoba). The animation above shows GOES-15 (left) and GOES-13 (right) Infrared imagery from 0000 UTC through 0430 UTC. The strong storm lifting northward over southwestern Manitoba is apparent, with an enhanced-V signature especially noticeable in the GOES-13 imagery.

A closer view of the tornadic supercell is shown below, with overlays of surface reports (metric units). The pulsing nature of the overshooting tops is evident in the fluctuation of the coldest cloud-top IR brightness temperatures (the coldest of which was -69º C, darker black color enhancement, on the 0300 UTC GOES-15 and 0315 UTC GOES-13 images). There are different apparent positions of the storms based on the satellite that views them because of parallax shifts. Such shifts are especially pronounced at higher latitudes with very tall storms.

A 1-km resolution Terra MODIS 11.0 µm Infrared image at 0331 UTC is shown below; the minimum cloud-top IR brightness temperature was -73º C.

Visible imagery from GOES-13 (above) and GOES-15 (below) showed the overshooting tops associated with the tornadic thunderstorm, as well as the rapidly expanding cirrus shield.

A closer view of the tornadic supercell from GOES-15 vs GOES-13 is shown below, with overlays of surface reports (metric units). The overshooting tops are again apparent on the images, along with an above-anvil plume (which is easier seen on the GOES-13 images, due to a more favorable forward-scattering viewing geometry). The robust convective development was first seen on the 2030 UTC images, in the vicinity of the Saskatchewan/Manitoba/North Dakota border region.

As an area of low pressure was deepening over eastern Montana, warm and humid air was surging northward into far southern Saskatchewan and Manitoba (surface analyses). GOES sounder derived product images (available from this site) of Convective Available Potential Energy (CAPE), Lifted Index, and Total Precipitable Water (below) showed that the environment across southern Manitoba was becoming increasingly unstable and moist leading up to the time of convective initiation.

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Wildfires continued to burn across parts of the interior of Alaska during the 22-25 July 2015 period, as is shown in GOES-15 (GOES-West) 0.63 µm visible channel and 3.9 µm shortwave IR images (above; click to play animation; also available as an MP4 movie file). Also of interest is: (1) the diurnal change of intensity and areal coverage of the fire hot spots (darker black to red pixels on the shortwave IR images), with the fires dying down at night, and (2) the change in direction of smoke transport, from westward on 22 July to eastward on 24 July. The switch in smoke transport direction was the result of changing winds associated with a broad area of low pressure moving across Alaska during that period (surface analyses).

A more detailed view of the fire hot spots was provided by 375-meter resolution (mapped onto a 1-km AWIPS grid) Suomi NPP VIIRS 3.74 µm shortwave IR images (below; click to play animation).

Many of the fires were burning in the general vicinity of the Utopia Creek, Indian Mountain airport (station identifier PAIM); a time series of surface observation from that site (below) showed that visibility was 1 mile or less due to smoke at times on 25 July.

Daily composites of Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images viewed using the SSEC RealEarth web map server are shown below.

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