Thursday, February 08, 2007
Cold Lingers; Snow Chances Increase
Josh Larson @ 6:00 AM
Now at 9 degrees below average for the month, all indications are that colder than normal conditions will remain for at least the next week to ten days, and perhaps thereafter. In addition, an enhanced southerly jet will increase the chance of (at least one) moderate to significant snowfall for our area for the week of Feb 12-19.
Slightly milder. Not quite as frigid today, but still considerably colder than average, with high temperatures -- under mostly sunny skies -- likely surpassing the freezing mark and approaching 35 degrees. Clear and quite cold once again tonight, with lows from near 10 across the coolest suburbs to the mid to upper teens downtown.
More of the same. Expect abundant sunshine on Friday but temperatures will still be quite chilly; we'll see afternoon highs near 35 and overnight lows ranging from the mid to upper teens.
Sunny & cold. Similar conditions will persist for the weekend, with mostly sunny skies both days and afternoon highs expected to top out in the upper 30s to near 40. With high pressure overhead, we'll hold onto clear and cold overnight conditions, with lows from the upper teens to low 20s.
Snow Lover's Crystal Ball 
Next Chance of Accumulating Snow:
Tuesday, Feb 13 - Wednesday, Feb 14
Probability: 40%
Potential Impact:
Commentary: The vast majority of computer models continue to suggest the potential for a winter storm during the Tuesday-Wednesday timeframe. In fact, it is striking both how consistent the models have been in 'generating' this storm and also how much moisture they have associated with the system.
Look for the usual model-waffle-dance over the next few days, which may include the guidance, at different times, showing the storm: (1) suppressed south; (2) pushed west -- warmer; (3) gone completely. However, from this vantage point it appears that many of the ingredients may be coming together for what might be a moderate to significant snow storm for the eastern US during the first half of next week.
Pattern Overview
Though we're already several weeks into our pattern flip from 'warm' to 'cold,' it looks like we'll hang onto generally negative temperature anomalies for at least the next 7-10 days and perhaps through the remainder of the month. But I do think, here in Washington, DC, that we've probably already experienced our coldest weather of the winter (earlier this week).
Want more snow? We're likely to see a more energized and active southern jet stream that will lift somewhat north in response to the slightly easing Arctic air next week, which will enhance snowfall chances for our area for the middle of the month -- not just for the first half of next week, but possibly thereafter as well. Quite unusual for this winter: the CPC predicts both colder than normal temperatures and above normal precipitation for our region for both the next 6-10 and 8-14 days.
Above: note the enhanced southern jet stream (lower left half of image) as depicted by the GFS model by next week; courtesy Unisys.com
Next week's forecast
Forecast highs/lows: 37/25 (normal = 46/29)
Forecast precip: Above normal!
Expect partly sunny skies on Monday with somewhat milder highs perhaps into the low to mid 40s; mostly cloudy and cold overnight with lows in the mid 20s. For the Tuesday-Wednesday period, see above, but I'll call for a 50/50 chance of snow, with highs in the upper 20s to lower 30s and overnight lows in the low to mid 20s. Thursday and Friday look to feature at least partly sunny skies, with highs in the upper 30s and lows in the mid 20s. There are some very early indications that another snow storm may be lurking to our south or southwest by the beginning of next weekend.
Today
Slightly milder. Not quite as frigid today, but still considerably colder than average, with high temperatures -- under mostly sunny skies -- likely surpassing the freezing mark and approaching 35 degrees. Clear and quite cold once again tonight, with lows from near 10 across the coolest suburbs to the mid to upper teens downtown.Tomorrow
More of the same. Expect abundant sunshine on Friday but temperatures will still be quite chilly; we'll see afternoon highs near 35 and overnight lows ranging from the mid to upper teens.Sunny & cold. Similar conditions will persist for the weekend, with mostly sunny skies both days and afternoon highs expected to top out in the upper 30s to near 40. With high pressure overhead, we'll hold onto clear and cold overnight conditions, with lows from the upper teens to low 20s.Next Chance of Accumulating Snow:
Tuesday, Feb 13 - Wednesday, Feb 14
Probability: 40%
Potential Impact:
Commentary: The vast majority of computer models continue to suggest the potential for a winter storm during the Tuesday-Wednesday timeframe. In fact, it is striking both how consistent the models have been in 'generating' this storm and also how much moisture they have associated with the system.
Look for the usual model-waffle-dance over the next few days, which may include the guidance, at different times, showing the storm: (1) suppressed south; (2) pushed west -- warmer; (3) gone completely. However, from this vantage point it appears that many of the ingredients may be coming together for what might be a moderate to significant snow storm for the eastern US during the first half of next week.
LARSON'S LONG-RANGE
Pattern Overview
Though we're already several weeks into our pattern flip from 'warm' to 'cold,' it looks like we'll hang onto generally negative temperature anomalies for at least the next 7-10 days and perhaps through the remainder of the month. But I do think, here in Washington, DC, that we've probably already experienced our coldest weather of the winter (earlier this week). Want more snow? We're likely to see a more energized and active southern jet stream that will lift somewhat north in response to the slightly easing Arctic air next week, which will enhance snowfall chances for our area for the middle of the month -- not just for the first half of next week, but possibly thereafter as well. Quite unusual for this winter: the CPC predicts both colder than normal temperatures and above normal precipitation for our region for both the next 6-10 and 8-14 days.
Above: note the enhanced southern jet stream (lower left half of image) as depicted by the GFS model by next week; courtesy Unisys.com
Next week's forecast
Forecast highs/lows: 37/25 (normal = 46/29)
Forecast precip: Above normal!
Expect partly sunny skies on Monday with somewhat milder highs perhaps into the low to mid 40s; mostly cloudy and cold overnight with lows in the mid 20s. For the Tuesday-Wednesday period, see above, but I'll call for a 50/50 chance of snow, with highs in the upper 20s to lower 30s and overnight lows in the low to mid 20s. Thursday and Friday look to feature at least partly sunny skies, with highs in the upper 30s and lows in the mid 20s. There are some very early indications that another snow storm may be lurking to our south or southwest by the beginning of next weekend.
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