3/31 – Brittany’s “Gloomy” Friday Evening Forecast
An upper level trough dropping out of the Rockies will deepen as it tracks across the northern/central Plains today. It`ll continue east through the upper Mississippi Valley and across the southern periphery of the Great Lakes Saturday. This track, and lack of southward digging, means that the cold front associated with this system will struggle to even reach the CWA. Expecting this boundary to washout before or as it reaches the northern Gulf of Mexico. Strong southerly flow in the lower levels has substantially increased low level moisture. Dewpoints are now in the upper 60s to lower 70s and the 12Z LIX sounding shows PW has risen from below an inch to nearly 1.5″. Although model soundings do show ample instability aloft, no severe thunderstorms across the CWA today or tonight due to: lack of low level ascent due to poor low level lapse rates, weak low level shear, presence of 700mb warm nose, and generally poor low level lapses rates due to no cooling in this layer. However, as noted on current radar and CAMs, light showers will pass across the region through the rest of today and possibly through early afternoon Saturday. At the same time, upper ridge situated over the Bay of Campeche will aide in temp moderation on Saturday with highs 5 to 10 degrees above normal and right on the tip of records.
Temperatures should fall back a bit on Sunday as combo of residual post frontal airmass tries to push in from the N/NE and cloudiness persists. Those clouds and potential for scattered showers/storms comes from a weak shortwave expected to race across the lower Mississippi River Valley late Sunday. Current guidance suggests the majority of appreciable rain impacts looks to be across northern LA and MS. The actual track of the weak shortwave, commonly a tougher feature for medium range models to resolve with time, will determine if local precip coverage is more or less than current forecast.