Western Heat Wave

Intense heat is beginning to develop across the Desert Southwest and will spread northward through the Great Basin and Central Valley of California; before it's over, the Pacific Northwest will also be enveloped in the swath of hot air.

The culprit is an atmospheric ridge, a northward bowing of the jet stream along the outer rim of a high pressure dome.  Within the ridge (beneath the dome), sinking air heats up and dries out and cloud formation is impaired; Santa Ana winds may also develop in Southern California.  Triple-digit heat is forecast for much of the region, with upper 90s (F) expected in Oregon and Washington.  Meteorologists warn that the high pressure ridge will remain in place through the upcoming weekend.

As one might expect, the Western heat wave is tied (meteorologically) to the Texas floods.  East of the ridge, the jet stream dips southward and this trough has spawned an upper level low over central Texas.  Counterclockwise winds around the low are combining with clockwise winds around a high pressure dome over the Southeast, pulling copious Gulf moisture across East Texas, Louisiana and the lower Mississippi Valley.  Once this atmospheric pattern shifts eastward, the flooding rains in Texas will cease and the Western heat will abate.

Brazos River Flooding

The Brazos River forms on the Llano Estacado at the junction of its Salt and Double Mountain Forks, northwest of Rule, Texas; it then flows northeastward to Seymour before angling southeast toward the Gulf of Mexico.  En route to the Gulf, the river passes through three major reservoirs: Possum Kingdom Lake, Lake Granbury and Lake Whitney; it also flows through Waco, passes west of College Station and flows west of Houston before emptying into the Gulf of Mexico at Freeport, Texas.

While the Brazos itself is 840 miles long, its watershed stretches back to eastern New Mexico; from its most distant tributary to its mouth, the River's watershed is 1280 miles in length, making it the 11th longest stream in the United States.  Over the past few weeks, heavy rainfall across the Brazos watershed has led to severe flooding, especially below the above mentioned reservoirs.  Not designed for flood control, these lakes must be partly drained as they fill in order to prevent catastrophic dam collapse.

As of this morning, the Brazos crested at 54.6 feet in Richmond, Texas (southwest of Houston), shattering a Century-old record by almost 4.5 feet; unfortunately, more rain is forecast across the watershed in the coming days.  To date, at least 6 individuals have been killed by the flooding and 31 Texas Counties have been declared disaster areas.  See also Texas: Land of Drought & Flood.