8/11 – Brittany’s “One Last Supermoon” Thursday Evening Forecast
The broad upper level analysis shows a ridge centered over the Rockies which expands over at least 2/3 of the country and trough digging across the northeast CONUS. That leaves the southeastern US under an area of weakness. When considering the atmospheric column, this morning`s upper air flight showed copious moisture with PW at 2.3″. That falls between the 90th percentile and average max for this time of year. A value that high definitely opens up the potential for localized heavy rainfall and high rainfall rates as well as high coverage. As with previous days, coverage along coastal areas will dwindle with time this afternoon while more inland areas see increase in coverage. The other important portion of the sounding is the wind field which supports slow movement and back building potential today. Thus, all signs point towards flash flooding potential. Instability is a bit less than recent soundings which will probably the biggest hindrance today with regards to average storm intensity. That may lead to fewer `hot spots` of higher rainfall totals and possibly just a few isolated ones.
Progressing into Friday and Saturday, what we`ll see is the eastern nose of the ridge NW of the region begin to extend southeastward towards the northern Gulf Coast. At the same time, the trough over the northeast will be shifting east. Drier air will then begin filtering from the north. This will start the trend of lowering POPs, but only for far northern portions of the CWA on Saturday. Lower rain chances probably not seen until beyond this forecast period.