El Nino Update

El Nino ended in May across the Equatorial Pacific with ENSO-neutral conditions now. Not only have sea surface temperatures fallen into the neutral range, they continue to fall and will likely be within La Nina conditions this Summer. Many of the computer model forecasts are beginning to agree that La Nina will settle in this Summer and continue the rest of the year. The NCEP CFS forecast is the heavy blue line:

It is not always the case, but there has been some research to indicate that the Atlantic Hurricane Season is enhanced during La Nina events. Last year's hurricane season confirmed the opposite, that during an El Nino year Atlantic hurricane activity is suppressed. We are already calling for an above-average hurricane season as a result of warmer-than-average sea surface temperatures in the Atlantic, and with the additional support of low wind shear from La Nina we should be on track for an active season.

Right now, tropical activity is low in the Gulf, Caribbean, and Atlantic Basin, but we will be monitoring for any developments!

(Visible satellite image 6/10/10 at 8:15 AM EDT)

Thunderstorms Possible Wednesday

After scattered showers moved through the state this morning, we're getting some breaks in the clouds which should allow the atmosphere to become more unstable this afternoon. Scattered showers and thunderstorms will be possible from this afternoon into tonight as a cold front moves into Central Virginia. This front won't bring in a cooler airmass, but will serve as a forcing mechanism for storm development. Some of the storms that form today could become severe with damaging wind gusts and large hail, but there is also the slim chance for an isolated brief tornado closer to the surface low tracking just north of Virginia. That low pressure system will head out to sea away from the Mid-Atlantic tomorrow morning.

Break From Heat & Humidity

We are finally getting a break from the much warmer-than-average heat and humidity that was prevalent since May 30th. The average high temperature in Richmond for early June is about 80-82 degrees. Here are the high temperatures since then:

May 30: 91
May 31: 90
June 1: 88
June 2: 88
June 3: 90
June 4: 92
June 5: 95 (2 degrees shy of the record high of 97 from 1943)
June 6: 96 (TIED the record high for this date from 1952)

So far this month our average temperature is about 10 degrees above normal for early June. But we aren't the only ones getting an unusual late Spring taste of high Summer heat:

With a strong ridge expected to develop over much of the East Coast at the end of this week, high temperatures will again rise 8-10 degrees above average by this weekend.

Rain Totals Sunday

Once again, storms were hit-and-miss today. On the map below, three isolated thunderstorms created narrow strips of moderate rainfall across our area. Highest totals were near Tappahannock and farther to the northeast.

Tornado Watch Until 8 PM Sunday

The northern half of Virginia is under a Tornado Watch until 8 PM. Severe weather will be possible this afternoon and evening across the entire state - including areas that are not in the watch.

Cold Front Coming!

A strong cold front will sweep through the Commonwealth this evening, likely triggering a line of strong to severe thunderstorms along and ahead of it late this afternoon and evening. Threats include damaging wind gusts 65 mph or stronger and hail the size of quarters.

Because the front will not clear the area until late this evening, this afternoon will still be hot and humid in Central Virginia with heat indices ranging 95-102 degrees, just like on Saturday. The high temperature Saturday in Richmond was 95 degrees, just two degrees shy of the record high for that date. But high temperatures are expected to be more typical of early June most of this week in the low-80's. High pressure will build back into the region at the end of the week, though, leading to another warm-up in the upper-80's and low-90's.