Subtropical moisture associated with weakening Hurricane John began to spread northward into the desert southwest, which was well depicted on AWIPS imagery of the GOES sounder total precipitable water (PW) derived product (below, left). This surge of moisture (QuickTime animation) prompted the Storm Prediction Center (SPC) to issue a Mesoscale Convective Discussion concerning heavy rainfall over the lower deserts of southern California and Arizona (below, right). GOES sounder and MODIS PW values compared favorably well, and at one point (08 UTC) the GOES sounder PW derived product indicated an isolated value of 61 mm (2.4 inches) over Arizona. Surface dew point temperatures reached the 60s and 70s F at some sites in the lower deserts, and rainfall from thunderstorms that subseqently developed was responsible for some flash flooding in parts of California and Arizona.

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Slow-moving Tropical Storm Ernesto produced winds of up to 76 mph and rainfall totals of 10-11 inches (map of rainfall totals) in the Norfolk/Virginia Beach VA area during the past 1-2 days (below, right), and caused widespread flooding problems across much of the Mid-Atlantic and Northeast regions of the US. Terra MODIS true color imagery (below, left) shows large amounts of sediment flowing offshore along the Virginia and North Carolina coasts today, as rain-swollen rivers and bays begin to drain into the Atlantic Ocean.

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Aqua and Terra MODIS true color imagery shows two areas of significant smoke today: across parts of the Pacific Northwest region of the US, and also across parts of Quebec and Labrador in eastern Canada (northeast of the cloud shield that is the remnants of Tropical Storm Ernesto spreading over the northeastern US and the eastern Great Lakes). The smoke in the northwestern US is due to ongoing wildfire activity that has persisted there for the last few weeks; the smoke in eastern Canada is likely from wildfires earlier in the week over Ontario, which was subsequently transported eastward. These smoke features were also evident as regions of elevated MODIS aerosol optical depth (AOD) on the IDEA products — IDEA trajectories initialized in eastern Washington state (where the maximum smoke thickness and associated AOD values were present) show that those aerosols will linger over WA during the next 1-2 days, while model wind fields suggest that the smoke in Quebec will continue to be transported slowly southeastward.

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Areas of radiation fog were forming during the overnight hours in the river valleys of southwestern Wisconsin, southeastern Minnesota, and northeastern Iowa. These narrow finger-like fog features were apparent on the MODIS 11-3.9 micrometer “fog/stratus product” (upper left panel) due the higher spatial resolution (1 km IR) and better spectral response of the MODIS IR channel data; on the 4 km resolution GOES-12 fog/stratus product (upper right panel), only a few isolated noise pixels showed up in that general region where river valley fog was forming. A closer view with surface observations plotted shows that a few sites were indeed reporting fog at that particular time (especially in the Wisconsin River valley).

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