Advected Layer Precipitable Water product for Hurricane Harvey

The CIRA advected layer precipitable water (ALPW) product for Hurricane Harvey is quite interesting:

The loop spans from 12Z 23 August to 12Z 29 August.  During that time period, we see the development of Hurricane Harvey in the western Gulf of Mexico.  There are clear indications of moisture convergence in the vertical during the early stages which would add confidence to a forecast of a strengthening tropical cyclone.  In the later periods of the loop, the system slows down along the coast of Texas.  It is clear that abundant moisture exists over a deep layer in the vertical in the vicinity of the slow-moving circulation.  High precipitation efficiency can be inferred from this imagery.  Abundant moisture over a deep layer in the vertical, very slow movement and high precipitation efficiency came together and contributed to the significant flooding in the vicinity of the circulation over coastal Texas.

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Hurricane Harvey

Just a few days after Hurricane Harvey made landfall in southeast Texas, Harvey has downgraded to a Tropical Storm, however it is still bringing torrential rainfall and massive flooding to southeast Texas and Louisiana. To recap, Hurricane Harvey made late-night landfall on 25 August 2017 as a Category 4 Hurricane.

Some of the latest precipitation totals are as high as 40+ inches as of late Monday evening, 28 August 2017. Flooding is widespread and power outages have affected many cities along the Gulf Coast, especially in Houston, Texas.  Below is an example of the number of river gauges observing major flooding along the Gulf Coast via the National Weather Service – Advanced Hydrologic Prediction Service website. The red and purple dots represent river gauges that are experiencing moderate to major flooding in and around the Houston, TX area.

If we look a little bit closer, at one of the purple gauges that represent major flooding, below is an image of the West Fork San Jacinto River Gauge near Conroe, TX, where the gauge is experiencing record flooding so far, peaking at a flood stage of 127.3 feet!

More precipitation and flooding are expected throughout the week, where recovery efforts will last for the next few months. Below is an image of the Imagery Band 5 (11.45um), an infrared band on the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on-board the Suomi-National Polar Orbiting Partnership satellite, showing the relative location of the storm along the Gulf Coast at 0816Z, 28 August 2017. The brightness temperature values are expressed from a range of colors; 180K (cooler colors representing temperatures of cold clouds/convective cloud tops) to 320K (warmer colors, land and ocean temperatures). The spatial resolution of the imaging band is at 375 meters.

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Interesting features along the west coast on 15 August 2017

The GOES-16 data posted on this page are preliminary, non-operational data and are undergoing testing.  Users bear all responsibility for inspecting the data prior to use and for the manner in which the data are utilized.

The following loop is the GOES-16 visible (0.64 micron) band centered along the California / Oregon border on the morning of 15 August 2017:

Low clouds exist along the coastline.  Offshore, vortex generation is occuring as the vortices move southward.  Inland, point sources of smoke with plumes drifting west are observed.  Mount Shasta can be seen in the southeast corner of the image with snow at higher elevations.  The shadow associated with the rising sun is readily seen on the western slope of the mountain.

Further south along the coast:

We observe a general decrease in the coverage of low clouds as the sun is rising.  Numerous vortices are observed associated with island effects.  The relative motion of low clouds can provide information on regions that experience gap flow.  Identify regions over the land where gap flow appears to exist.  Consider how useful this imagery could be towards visibility and ceiling monitoring and short-term forecasting.

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Fires in Pacific Northwest

The Pacific Northwest (PNW), that is, the states of Washington, Oregon, Idaho and Western Montana are experiencing a significant heat wave right now. Air temperatures are scorching hot, with temperatures in the high 90’s and low 100’s. An amplified upper-level ridge has been quite persistent over the PNW, bringing the high temperatures and dry air to the area.

Due to the abnormally dry conditions, fires have been initiated and are scattered within the PNW. Fires can be seen below via two polar products: the Day/Night Band (DNB, 0.7um) and the Imagery Band 4 (I-4, 3.74um). The two products work in complement with one another. The DNB assists in utilizing a sun/moon reflectance model that illuminates atmospheric features, senses emitted lights, and assists with cloud monitoring during the nighttime, while the I-4 band senses the ‘fire hotspots’, areas that exude high brightness temperatures in comparison to the nearby environment. The I-4 band also assists the DNB in differentiating between what emitted lights are city lights, and what lights are the emitted lights from the fires.

It is important to note that the DNB and I-4 band are at two different spatial resolutions; DNB at 750 meters an the I-4 band at 375 meters. The static images can be seen below at 0924Z (0224 local time), 3 August 2017.



I-4 Band


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