The National Weather Service in Norman has issued a flood watch for our coverage area due to the expectation of a major rainfall event Friday and Saturday.
The primary forecast issue continues to be a significant rainfall event expected Friday into Saturday. A Flood Watch has been issued for this period.
For today, another hot and humid afternoon is expected. High temperatures will once again be low 90Fs (+5-8 deg F above average) with dew points in the mid-60Fs to low 70Fs. This will result in heat index values in the 90Fs.
For tonight, showers and thunderstorms are expected to develop along a cold front in southwest Kansas and ahead of a trough across the Texas panhandle. This convection will spread eastward into western Oklahoma/western north Texas tonight into Friday
By Friday morning through early Saturday afternoon, widespread, occasionally heavy rainfall is forecast across much of the area. Several meteorological factors will be favorable for significant rainfall totals:
1) A cold front is forecast to slowly move southward. The heaviest rainfall will likely occur along and just north of the surface front. Significant isentropic ascent and frontogenesis is forecast at ~850-700 mb (just north of of surface front). This ascent is expected to progress west to east through the period.
2) An elongated, shortwave trough will slowly move across the Southern Plains. This wave and attendant local vorticity maxima will provide an additional source of ascent.
3) Precipitable water values are forecast to be 1.8 to 2.25"+. Moisture from both the remnants of Tropical Depression 19 in the Pacific and from the western Gulf of Mexico will advect into the
area, which will result in a anomalously high (potentially record-breaking) precipitable water values. As result of this moist environment, warm cloud depths are forecast to be >12,000 ft AGL.
This will result in efficient, warm-rain processes.
Based on the aforementioned analysis, a Flood Watch has been issued from 12Z Friday to 18Z Saturday for the northern two-thirds of Oklahoma and western north Texas. Current expectations are 3
to 7" of rainfall in the Flood Watch area.
For Sunday, there is some uncertainty on how quickly the the system will exit. The ECMWF lingers the system a little longer than the GFS. For now, will maintain a low to moderate chance of showers with a slight chance of thunder.
For Monday, warmer temperatures are expected with a return to southerly winds and more insolation. There is only be a low chance of showers/storms, primarily across the eastern half of Oklahoma.
By Tuesday, a longwave trough is still forecast to amplify across the Plains. The 20/00Z ECMWF has a normalized height anomaly associated with trough of at least 1.5 standard deviations below average in Minnesota. As the trough amplifies, it will drive a
cold front south into the Southern Plains. The front is forecast to pass on Tuesday with a chance of showers/storms. Cooler, below-average temperatures are expected in its wake for Wednesday.