Sea Fog

Sea fog rolled into the area this morning and hung around for much of the day for the beaches.
From Sarasota County northward to western Pasco County, the damp cool air and clouds that make up sea fog made for a cloudy Wednesday.

The sun did eventually break out for Tampa and areas east and as a result air temperatures jumped to the upper 70's and lower 80's. However, along the beaches of Pasco, Pinellas, Manatee and Sarasota counties, the fog kept temperatures down in the low 70's with just a little sunshine breaking out late in the day. Many areas are still socked in with the fog as I write this.

I have included a visible satellite image from this afternoon that depicts the fog along the coast. Most of the white shaded area (fog/clouds) along the coast is the sea fog. This is typically only visible on "visible" satellite imagery during the day. We use visible imagery to best locate fog, as infrared imagery does not show it very well. Visible imagery uses reflected sunlight (like a camera) while infrared imagery uses temperature differences to sort between the surface and the clouds above. Because the clouds are on the surface when fog forms, the temperature difference is very little and as a result infrared imagery cannot differentiate between the the two.

Sea fog typically forms when the water surface temperatures are very close to the dew point of the airmass located over the water. The local winds then blow toward land, bringing that saturated airmass onshore as sea fog. This time of year, the water temperatures are in the 60's for the most part and when an air mass moves in with dew points in that range, the air mass becomes saturated. This causes the fog to form. Today's winds were light out of the south, bringing in moist air right off the Gulf of Mexico. The main mechanisms that can alleviate the fog, are surface heating, dry air and stronger winds.

This fog should appear again tomorrow morning as we see winds out of the SW, but those winds will increase late in the day allowing the fog to scour out. A cold front moving in later tomorrow will switch the winds around to the NW then N bringing in drier air (lower dewpoints). That will eliminate the threat for the sea fog on Friday.