Waning Winter Wednesday

The spring catalogues coming through the mail slot have been accompanied by spring-like temperatures in the Washington DC area this afternoon. At 10¾ hours of daylight, our sunshine 5 weeks before the equinox is as strong as it was the week before Halloween. South-facing roofs and some sections of grass are now bare in this outside-the-Beltway neighborhood. Temperatures around the metro area are in the upper 50s with some 60s in the southern fringes of the region.

A low pressure area moving northeastward from Oklahoma toward the Great Lakes on this afternoon's weather map will keep us in the warm temperatures for a couple more days until the colder air behind it brings some of the chilliest (no, not "silliest", Spell-Check!) readings of the season for the weekend. After that, some type of storm activity is likely to develop along the front to the south, but nothing major is showing up yet. We'll be keeping an eye on it as usual in the days ahead. (Even though the PM Update will be taking a "non-snow" day tomorrow, we'll still be watching while we catch up on some other projects.)

Surface weather map at 1pm today from HPC/NWS/NOAA

Tonight and Tomorrow

For tonight, lows will be near 40 in the city to the mid 30s in the 'burbs under scattered to broken clouds. Tomorrow's highs will be near 60 with some scattered clouds.

Budget Blues

Yesterday's WaPo Federal Diary reports that budget cuts are prompting the National Weather Service to offer early retirement to about 1000 employees. Based on past experience, only 50 are likely to volunteer, but naturally such a program impacts the areas with the most experience. The St. Petersburg Times points out that 13 out of 42, or 30%, of the staff members at the National Hurricane Center are eligible. This has prompted Florida Senator Bill Nelson to say,

"That's the most ridiculous budgetary policy decision I've ever heard, when you're dealing with a matter of life and death, of inbound hurricanes."

Calling Inspector Morse

There hasn't been much of a thaw today except in the sunnier spots. Temperatures are maxing out mainly in the high 30s, but melting will be accelerating into this week. The model statistical outputs are all suggesting at least an approach to the 60 degree level by midweek.

Tonight and Tomorrow

For tonight, lows under partly cloudy skies will range from the upper 20s in the city to low 20s in the 'burbs. The warmup begins tomorrow with highs around 47 and partly cloudy skies.

Snow Intensity and Depth

The development of the storm which brought our snow over the weekend and record-breaking amounts to New York City and central New England will certainly provide a lot of material for future investigations. Detailed data on snowfall rates are hard to obtain, because snowfall measurement is very subjective and therefore not easily automated. I took a stab at analyzing the intensity of the storm over time with the chart on the right. It's based on the "hourlies" (METAR data, or aviation reports), from Washington National for the 36-hr period from early Saturday morning through early Sunday afternoon.

Time is shown on the horizontal scale. Bear in mind that distance along the axis is not directly proportional to time, because the observations are not evenly distributed in time. They are made every hour on the hour, and then whenever a change in conditions requires an update. Although Microsoft® Excel is the Swiss Army Knife® of data analysis, it is notoriously inept at handling unevenly distributed data points.

The vertical scale represents the type and intensity of precipitation. Positive values are snow reports, and negative values are rain reports. A magnitude of 1 is "light", 2 is "moderate", and 3 is "heavy". You can see that most of the morning had intermittent light rain, then light snow mixing in the afternoon. This became all snow by late afternoon, occasionally moderate through the evening. The real fun began after midnight, when there were 8 reports of heavy snow. By 9am, the steady snow was over, and there was a snow flurry in early afternoon (and possibly 1 or 2 more after the cutoff time in the chart).

I think an important factor in the higher snow depths which were recorded was not just the usual temperature-dependent frozen-to-liquid ratio, but also the very high rate of fall, which prevented the kind of settling which would happen over a longer period. Depths have visibly decreased a lot today, but I would suggest that this is more an effect of settling, rather than melting, given the temperatures we've had.

Chart © CapitalWeather.com, photo © Kevin Ambrose

Taking Snow for an Answer

After 6 weeks of non-winter, conditions are shaping up for a classic Gulf of Mexico to Cape Hatteras to Cape Cod snowstorm track, and the Washington DC area is included in the festivities (or not, depending on your view of snow). If you're just joining us and want the background, check out Camden's excellent review below. Otherwise, here's the bottom line based on the latest model runs from this afternoon's data:

Timing: Light snow will overspread the area from the southwest during the morning tomorrow, increasing in intensity toward evening. The heaviest snow will fall overnight Saturday, tapering off Sunday morning.

Amount: The most likely accumulations in the immediate DC area are in the range of 5-8", although some areas of more than 8" are possible.

CapitalWeather.com chart above, photo © Kevin Ambrose

Winter Storm Forecast: Saturday midday, Feb. 11 -- Sunday A.M., Feb. 12
	TIMELINE 10am SAT to 2pm: Light snow overspreads the area from SW to NE. Best guess for first flake inside the beltway is around 11am. 2pm to 5pm: Snow increases in coverage and intensity. 1-2" possible. 5pm to 3am SUN: Snow, heavy at times. 3-4" possible in metro area. 3am to 11am: Snow gradually diminishes SW to NE - up to 2" additional accumulation, more N & E. Becoming windy, cold.
Storm Impact: Travelcast:Schoolcast (Mon.):

Commentary

Don't be fooled by the widespread sunshine and seasonable temperatures (low 40s) this afternoon. There is plenty of cold air available for this system, so the main risk to the forecast is that the storm will track further east and give less precipitation, rather than mixing with rain in the DC area. There is plenty of moisture available along the Gulf Coast; latest radar shows moderate to heavy rain as far east as western Alabama. Barometric pressure falls along the Louisiana and Alabama coast over the last several hours have been at rates as high as nearly 2 mb/hr, which indicates strong storm development.

The CapitalWeather.com team will be monitoring the storm's progress through the evening, including the model runs from data just now being collected, and posting an update around midnight.

Round Rodent vs. Regression

Happy Groundhog Day! Even the most diehard snow fan must admit that temperatures pushing toward 60°, and even above on the southern fringes of the region, can't be all bad on the 2nd day of February. Meanwhile, unless you've been totally isolated from all media, you know by now that our Phurry Phriend Phil has done his duty for another year by seeing his shadow and predicting 6 more weeks of winter.

Regional radar is mainly clear as clouds gradually increase from a developing low pressure area moving northeastward from the Gulf states. Some widely scattered showers have reached into West Virginia and southwestern Pennsylvania. This low will bring some rain to the area overnight. Current indications are that the next system may end as some wet snow or flurries on Sunday, with little or no accumulation in the immediate area. The models are becoming more consistent on this, but there is still some difference in timing.

Tonight and Tomorrow

Clouds will increase this evening, with showers beginning around 1am and lows in the mid 40s. Showers will end in the morning tomorrow, with some sun in the afternoon and highs in the upper 50s.

Snow Statistics

A couple of weeks ago, we noted that, statistically at least, January snowfall gives virtually no clue to February's amount. Today's chart shows that there is one element which does provide some insight, and that is February temperature. Colder temperatures do correlate to some extent with more snow. As some site visitors have pointed out in earlier comments, however, this is far from a lock. There is a lot of scatter in the data, and some quite cold Februaries have had little or no snow, even a few which averaged below 30° (13° colder than this January).

The dashed regression line shows that for each degree the monthly average temperature is below about 44.1°, the expected monthly snow total increases by about ¾". The value of R² indicates that about 25% of the variance in snow amounts is accounted for by the average temperature.

CapitalWeather.com chart from NWS data

DC Comics

Tom Toles' cartoon in today's WaPo commenting on political science:

"But With a Different Feeling"

Here's the statistic Bob Ryan was probably referring to last night: In 54 years of history, Washington National has averaged 0.2 thunderstorms in January out of the 30.6 total per year. This is now the third time thunder has been reported this month. Thunder was last observed in January before this year on New Year's Day, 2003.

CapitalWeather.com chart from NWS data

Following the fast-moving cold front which passed through last night, it's a blustery January day in the Washington DC metro area, but temperatures are close to seasonal levels, in the low 40s. Winds gusting as high as 45 mph in some places are making it feel a lot colder. With a low of 35 last night, whether today becomes only the second day this month of below-average temperatures depends on how cold it gets before midnight.

A few snow flurries are widely scattered around the area, but most of the activity is west of the Shenandoah Valley. Hagerstown was reporting 1¾ mile visibility in light snow around 3:30.

Tonight and Tomorrow

Lows tonight should be in the upper 20s with partly cloudy skies and diminishing winds. Tomorrow will be sunny with highs in the low 40s.

Broadcast News

Set the TiVo! From the WaPo TV listings comes the news that Doug Hill has escaped the 2½ minute straightjacket to host a 30 minute special about the WeatherBug network tonight. The show is on at 8:00, Channel 7. Way to go, Doug!

DC Comics

Tom Toles has a cartoon in today's WaPo on the subject of the Katrina reports we mentioned yesterday.

Party Like It's 1950

Even the snow-lovers would have to admit that a nice day is better than an ice day. Except for the notoriously unrepresentative locations near cold bodies of water, temperatures were in the 60s by early afternoon today in the Washington DC metro area. To the south, Stafford claimed a reading of 68 by 3pm. That certainly qualifies as a nice day in January, on average the coldest month. The best part is that the warmth is not accompanied by rain (yet), and you don't have to wait until The Midnight Hour. It's not warm enough to set a record in the century-plus history of the city locations, but for Dulles today easily surpasses the old record of 57 in 1991. (That leaves only 2 January dates, tomorrow and the 10th, which have never exceeded 60 there.)

A low pressure area working its way northeastward toward the Great Lakes will bring the threat of showers to our region tomorrow, but for now, the radar is clear for hundreds of miles.

Tonight and Tomorrow

For tonight, lows in the low to mid 40s will be accompanied by increasing cloudiness. Tomorrow's highs will be in the low 60s under mostly cloudy skies and a 50% chance of showers in the afternoon or evening.

How Warm Is It?

This year's warm start has many people asking how unusual it is for January. The monthly average temperature of 42.7 through yesterday has moved up the charts to 9th place on the 135-year official Washington hit parade.

One record which is not in jeopardy of being broken any time soon, however, is the amazing 48 degree average in January 1950. That month's 13-degree excess over the January average for the entire period of record makes it the warmest month of all time in Washington history, relative to average. It's enough to be warm for March (3.2 degrees above the period-of-record average) and equal to or warmer than the 2 coldest Aprils. The chart of the daily temperatures from the NOAA National Climatic Data Center shows that the month started off warm, with highs in the 70s on 3 consecutive days in the first week and reaching 70 again on the 10th. The coldest day was the 20th, with a high of 35 and a low of 22, but after that the temperature rose steadily for 6 straight days, reaching over 70 on 3 of them, including the all-time January record of 79 on the 26th. Five of those daily records still stand over half a century later.

CapitalWeather.com chart from NWS monthly records

It Could Happen the Day After Tomorrow (Or Not)

• Last week's IMHO distinctly underwhelming Category 3 Hurricane Destroys New York will be followed by F5 Tornado Does Dallas on TWC's "It Could Happen Tomorrow", Sunday at 9:30pm.
  
• WeatherTalk radio has inexplicably invited conspiracy nut Scott Stevens, tinfoil hat and all, back for a second week, Sunday at 3pm, WCBM 680. As the CarTalk guys say, "You've wasted another perfectly good hour . . ."
  
• A site visitor has pointed us to the dcrtv news that the, shall we say, "flamboyant" Joe Bastardi has been pulled from national broadcast duty by AccuWeather. I have personally noted his absence from CNBC since late summer or early fall. (Currently at the top of dcrtv is an interesting item about Rush and Daryn, but that's a subject for another blog.)

Winter Marches On

Some clouds associated with a weak warm front have moved out, and temperatures throughout the Washington DC metro area have reached or exceeded 50 degrees by mid afternoon today. Some mixed precipitation earlier on radar from the West Virginia panhandle northeastward to Pennsylvania was apparently not reaching the ground, and it has now disappeared. Tomorrow looks like a fine day to sneak out early for your favorite outdoor activity (as long as it doesn't involve snow), so get your excuses ready.

Tonight and Tomorrow

Lows tonight under a few clouds should be around 37 in the city, lower 30s in the colder 'burbs. Mostly sunny and low 60s are on tap for tomorrow.

Betting on Snow

Whether you believe in the gambler's fallacy (a coin is more likely to come up heads after 9 consecutive tails) or persistence (a coin is more likely to come up tails after 9 consecutive tails), you don't have much support in Washington snow statistics. Last month, we looked at whether December snowfall amounts can give any clue for January and found that they were almost completely uncorrelated. If it's possible, February snowfall in DC is even less correlated with January. The chart shows an almost completely flat regression line, with a correlation coefficient nearly equal to 0. Stay tuned as we try to figure out what Momma Nature's cooking up for the February menu.

Six out of Seven EPA Administrators Recommend

It's stuck under an equal-sized White House Iraq photo-op on page A4 (dead last in the online A section), but today's WaPo has an article about a meeting in which 6 former EPA administrators, 5 of whom are Republicans, recommended mandatory limits on CO2 and other greenhouse gas emissions. The immediately previous administrator, Mike Leavitt, who is now secretary of HHS, could not attend because of "schedule conflicts". Russell Train, who held the position from 1973 to 1977 under Nixon and Ford, said,

"This is not a sort of short-term cycle problem. This is a major disaster for the world. To say we'll deal with it later and try to push it away is dishonest to the people, and self-destructive."

Come on, Mr. Train, stop being so partisan!