Sunday Night/Monday

The Numerical Guidance has centered on a late Sunday Night/Monday Morning rain event. Accumulations across the Delta will be around 0.5 inches. A quick look at some Radar and Visible Satellite Imagery Monday morning will tell us more about where convection is taking place, and where higher rainfall amounts can be expected. At this range it is impossible to forecast the exact location of Thunderstorms at the Micro-scale (County Level).  There is a small body of research that suggests convections occurs along thermal boundaries created by soil, vegetation, hydrologic features, etc... I'll discuss that later in detail and include a few links to interesting papers.

This time of year mechanical forcing in the atmosphere (Dynamics) is still the main source of rainfall, not convection (Thunderstorms), so it is beneficial to follow the movement of the atmosphere and track where it will act to balance itself; after all, weather is nothing more than the air around you trying to reach equilibrium.

Below is a forecast graphic from the Canadian Ensemble Prediction System. The red numbers represent "members" of the ensemble. Clustering of members increases forecast confidence. Notice the cluster to the west of the delta valid for 12 hours before we expect any rain. The model places us inside the 5 Millimeter (0.2 Inches) line during the Sunday Night/Monday morning time period.

Though the rains right now are most likely frustrating to you, it is important to keep in mind the drought conditions. Things won't take long to dry up since temperatures will be in the mid 70's next week. 

Climatologists are expecting ENSO to go neutral as we move into May and June, which means we will be in neither La Nina or El Nino conditions.