Thursday, June 28, 2007

Scattered Showers Still Somewhat Spotty

** Severe Thunderstorm Watch in Effect Until 11 PM **


Warm, humid, scattered thunderstorms. Ahead of a cold front moving slowly but steadily southeastward from the Great Lakes, showers and storms have been fairly widely scattered across the Washington metro area this afternoon. National had a light thunderstorm early this afternoon, but total rainfall was a pitiful 0.02". The brief shower at Dulles was good for only 0.01". One or two more lines of storms are likely to bring rain and thunder to at least some parts of the metro area through the evening and possibly into the morning hours; a few storms could be severe. Cooler temperatures will arrive tomorrow in time for a more pleasant weekend.

Tonight and Tomorrow

Evening storms likely, gradually cooler and less humid. Showers and thunderstorms will be scattered through the region (60% chance at any given location) through this evening and possibly into the overnight hours. Otherwise, warm and humid conditions will continue for the rest of tonight with lows 69-75°. Considerable clouds and showers tomorrow morning could linger into the afternoon, though some clearing is possible by late afternoon. Highs will be 80-84° with gradually decreasing humidity.

For the outlook through the weekend and beyond with Larson's Long-Range, scroll on down to Josh's post below.

Rainfall Review

In marked contrast to exactly a year ago, when torrential rains caused a state of emergency to be declared, yesterday's showers were extremely spotty through the metro region. Even the small area of dark blue in western MoCo on the NWS precipitation analysis map to the right represents 0.5" or less. As has frequently been the case recently, areas from northeast of Baltimore to above the Mason-Dixon line have received much more generous amounts. In the latest weekly drought report, the metro region is in the Moderate Drought range on the Long Term Palmer Index.

Tropical Topics

A tropical wave is producing showers across the Bahamas and portions of Florida. Any development is expected to be slow as the system moves northwestward, but locally heavy rains are likely.

Wednesday, June 27, 2007

DC: DisComfort


Partly sunny, warm, muggy, some storms. It's another muggy afternoon in the Washington metro area with some popup thunderstorms already appearing earlier. After reaching at least 93° by 1pm, National's temperature retreated to 82° the following hour in a very light thunderstorm, but Dulles surged ahead to 95° by mid afternoon. To the south, traditionally warm Fredericksburg combined a dewpoint of 75° with a temperature of 99° to get a sweat-soaked heat index of 111.

At post time, the only warnings in effect were marine warnings for Chesapeake Bay and severe thunderstorm warnings in south-central and southwestern Virginia. No watches were posted. Here at Update Central in west-central MoCo, a slight rumble of thunder has just begun. After another day of discomfort, more pleasant conditions are in prospect for the upcoming weekend.

Tonight and Tomorrow

Chance of evening storms, continued muggy. Showers and thunderstorms will be scattered across the region (30% chance at any given location) through this evening. For the rest of tonight, warm and humid conditions will continue with lows in the mid 70s downtown and the low 70s in the 'burbs. Tomorrow will be hot and humid with highs generally 90-94° and thunderstorms likely, some possibly severe, in the afternoon and evening.

For the outlook through the rest of the week and the weekend, scroll on down to Dan's post below.

Climate Corner

If you're confused (or just curious) about some of the claims that have been made regarding the atmospheric thermodynamic effects of increasing CO2, check out the latest post at by Spencer Weaert, called "A Saturated Gassy Argument".

The Weather Channel's Forecast Earth blog had a post yesterday by our own Andrew Freedman on the Emily Yoffe WaPo op-ed cited earlier by Dan.

Drought Watch

A June 22 article in The Week magazine, "Desperate for Water", surveys the effects of long-term drought in the western U.S.

Monday, June 25, 2007

Some Say "Sultry," Many Mutter "Muggy"


Mostly sunny, warm, muggy. Whether you call it "sultry," "muggy," or "yucky," classic DC heat and humidity are back in the Washington metro area: temperatures mainly in the upper 80s, dewpoints pushing into the 70s. Late this afternoon, Culpeper's readings of 90° (temperature) and 72° (dewpoint) produced a heat index of 97, while a southerly river breeze kept the National Airport official temperature and dewpoint to 87° and 69°, respectively, for a more bearable heat index of 91.

After several days of discomfort, more pleasant conditions are predicted for next weekend.

Tonight and Tomorrow

Chance of evening storms, continued muggy. There is a 30% chance of scattered thunderstorms through this evening, mainly to the south and west of the immediate metro area. Warm and muggy conditions will prevail overnight with lows from the low 70s downtown to some upper 60s in the 'burbs. Tomorrow will be hazy, warm, and humid with a 25% chance of afternoon or evening thundershowers and highs 89-93°, heat indices reaching the mid or upper 90s.

For the outlook through the rest of the week, scroll on down to Jason's post below.

Tropical Topics

The UK Met Office last week issued a hurricane season forecast which is considerably tamer than those issued earlier by NOAA and Colorado State. The UK forecast, which is being issued publicly for the first time, uses a dynamical (physical) model of the ocean/atmosphere system, called GloSea, as opposed to the mainly statistical techniques used in other forecasts. The prediction calls for 10 named storms in the July-November period, slightly less than the recent historical average of 12.4.

Climate Corner

In an exclusive report, The Onion last week detailed the Bush Administration's latest climate change program, the NACI (National Air Conditioner Initiative). Bush is quoted as saying,
"Global warming threatens us all, whether we're mowing our lawns, rafting down a river in a national park, or driving to the end of the driveway to get our mail. The task that lies ahead is undeniably hard. But if we do not succeed, we will be profoundly inconvenienced. And I promise you: America will not let that happen."
Graphic courtesy The Onion.

Seasonal Outlook

Latest seasonal forecast: Click here.

Latest 3-month temperature outlook from Climate Prediction Center/NWS/NOAA.