Monday, February 21, 2005

Mid-day update: Do not break arm patting self on back :)

How about that classic DC President's Day snow storm? What snow, you ask. Well, there were at least 10 or 12 lonely flakes drifting down mid-afternoon yesterday. If you blinked, you probably missed them, but our hawk-eyed observers kept you up to date. After some light rain during the night, the sun broke through the overcast about 9-10 am this morning, and temperatures are headed well up into the 50's in the metro area, depending on the amount of sun we get. Despite a nominal mostly high overcast, at 1pm temperatures in the immediate area ranged from a low of 50 at Quantico to 59 at Stafford and Culpeper. Fredericksburg VA had already reached 61 by noon and 63 at 1pm. There is still the chance of some showers as a complex low pressure area moves through the Northeast and a cold front approaches from the west. There is currently a strong squall line moving through Tennessee, but that will not be reaching our area.

As Jason has already noted, the CapitalWeather team did an excellent job handling the latest storm system. As I indicated in my Friday pm update, there were already signs that snow, if any, would change to rain, and we updated the outlook through comments and postings through the weekend. My reasoning for being skeptical of snow was the following:

When I was but a wee lad in the shire long, long ago and far, far away I learned an important lesson in the kitchen of Momma Nature's Down East Weather Grill (besides "Don't mess with Momma!"). That was that the secret sauce absolutely required to cook up a nice batch of fluffy snow is . . . Are you ready for this? COLD AIR! It's all very nice to have a shot of cold air come in during the week, and there's the mountain factor contributing to cold air damming, which the models still can't get a good handle on, but there also needs to be some support from the upper-air flow for this to happen. I just didn't see that without any kind of trough along the east coast, and none was predicted by the models, either. The official minimum temperature for DC turned out to be 35 last night. Another clue was Kevin's comment which noted the breakout of precip in IL and KY Saturday way ahead of the development of the surface low back a few states. This was an indication that the juicy tropical moisture previously pumped in by the low off California was racing ahead of the necessary vertical motion, which, of course, is another crucial ingredient in cooking up precip, whether frozen or not. Note that DCA eventually received a whopping 0.06" of precipitation in the 24 hours ending at 7am today. Even if all of that had been frozen, the depth would have been way less than an inch.

So, hopefully without sounding more like a geezer than I already am, let me say that we have already seen several times this winter that the models are great as far as they can go, but there is still a role for good old-fashioned synoptic analysis: Look at the actual data and interpret what is going on in terms of hard-earned experience. I expect I will have more to say on this subject as time goes on.

News items
The Washington Post reports this morning on a memo expressing concern over the effects of National Weather Service budget cuts.

The American Association for the Advancement of Science reported at its annual meeting in Washington on Thursday that "ocean temperatures are rising because of human activity, and the global impact could be severe".
There was also a report that aging in the brain can be slowed; perhaps there is hope for the geezer weather guy after all!

Seasonal Outlook

Latest seasonal forecast: Click here.

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