Thursday, January 18, 2007
We've Got the Cold...What About Snow?
Josh Larson @ 2:30 PM
First off, despite what the NWS or other forecast outlets may be saying, chances for precipitation -- frozen or otherwise -- are quite low for later today into tomorrow. The most we might see are a few wet snow flakes or sleet pellets mixed in with sprinkles. Snow-lovers, however, take heart, as we keep plenty of cold air around over the upcoming week to ten days and there are at least two storm threats during that period.
Nothing to see here! Look for a chilly start this morning with mostly cloudy skies, which with thicken as the day wears on. By late afternoon, a couple sprinkles (perhaps mixed with a wet snow flake) are possible - especially in areas south and east of the city. Expect afternoon highs near 37. For the evening, expect a slight chance of a sprinkle or flurry; overnight lows will be near freezing. Needless to say: no accumulation.
A bit milder. A few morning clouds are possible Friday, but skies will quickly give way to sunny conditions. Look for slightly milder highs near our average of 42 degrees. Clear and cool overnight, with lows from the low 20s across the 'burbs to the upper 20s downtown.
Saturday: Frigid. A re-enforcing shot of cold air will bring very cold temperatures to the area on Saturday with highs struggling to make above it 30 despite abundant sunshine. Clear and quite cold Saturday night with lows ranging from the mid teens to the lower 20s.
Sunday: All eyes to our southwest. Not nearly as bitter on Sunday, but still below average, with increasing clouds during the day giving way to afternoon highs in the upper 30s. We'll be carefully watching an area of low pressure to the southwest which has a slight chance of bringing precipitation to the area Sunday night into Monday.
Snow Lover's Crystal Ball 
Next Chance of Accumulating Snow:
Sunday, Jan 21 - Tuesday, Jan 23
Probability: 30%
Potential Impact:
Commentary: Several computer models are suggesting the potential for an area of low pressure and associated wintry weather to approach from the south and west on Sunday, which, depending on timing, may bring precipitation to the area during the Sun-Tue period. Computer models are in 3 different camps: (1) Modest storm with mostly or all snow; (2) Suppressed scenario with storm staying to the south; (3) Warmer scenario with mostly rain. In my belief, the most likely scenarios are in that order.
Note, too, that several models also hint at a mid- to late-week storm, which is likely to be stronger than the aforementioned Sun-Mon system but cold just as easily be rain as snow from this far vantage point.
Pattern Overview
Make no mistake about it, we are now into a pattern that will likely bring near to below-normal temperatures for the remainder of the month. A deep ridge southeast of Alaska will keep a strong trough of over the eastern two-thirds of the nation, allowing for cross-polar flow from Canada to drain polar air into our area. A caveat, however: with this general setup, my thinking is that while there is certainly potential for snow over the upcoming period, it is almost as likely that the storm track will be suppressed to the south of us, leaving DC high and dry. I also believe that over the next week our temperatures are much more likely to bust "cold" or lower than model guidance than the opposite, so I've gone lower than most other outlets.
Pictured above: the GFS' representation of a deep trough over the eastern US much if not all of next week; courtesy Unisys.com.
Next week's forecast
Forecast highs/lows: 37/24 (normal = 42/27)
Forecast precip: Below normal??
Expect mostly cloudy skies on Monday with a chance of lingering snow showers; highs will be in the mid 30s with overnight lows in the mid 20s. More clouds than sun on Tuesday with a slight chance of flurries and highs in the upper 30s with lows in the low to mid 20s. Wednesday is likely to feature times of clouds and sun with highs from 35-40 and lows in the 20s. Thursday and Friday will feature mostly cloudy skies with a chance of rain or snow with highs from the low 30s to near 40 with overnight lows remaining in the 20s.
Today
Nothing to see here! Look for a chilly start this morning with mostly cloudy skies, which with thicken as the day wears on. By late afternoon, a couple sprinkles (perhaps mixed with a wet snow flake) are possible - especially in areas south and east of the city. Expect afternoon highs near 37. For the evening, expect a slight chance of a sprinkle or flurry; overnight lows will be near freezing. Needless to say: no accumulation.Tomorrow
A bit milder. A few morning clouds are possible Friday, but skies will quickly give way to sunny conditions. Look for slightly milder highs near our average of 42 degrees. Clear and cool overnight, with lows from the low 20s across the 'burbs to the upper 20s downtown. Saturday: Frigid. A re-enforcing shot of cold air will bring very cold temperatures to the area on Saturday with highs struggling to make above it 30 despite abundant sunshine. Clear and quite cold Saturday night with lows ranging from the mid teens to the lower 20s. Sunday: All eyes to our southwest. Not nearly as bitter on Sunday, but still below average, with increasing clouds during the day giving way to afternoon highs in the upper 30s. We'll be carefully watching an area of low pressure to the southwest which has a slight chance of bringing precipitation to the area Sunday night into Monday.Next Chance of Accumulating Snow:
Sunday, Jan 21 - Tuesday, Jan 23
Probability: 30%
Potential Impact:
Commentary: Several computer models are suggesting the potential for an area of low pressure and associated wintry weather to approach from the south and west on Sunday, which, depending on timing, may bring precipitation to the area during the Sun-Tue period. Computer models are in 3 different camps: (1) Modest storm with mostly or all snow; (2) Suppressed scenario with storm staying to the south; (3) Warmer scenario with mostly rain. In my belief, the most likely scenarios are in that order.
Note, too, that several models also hint at a mid- to late-week storm, which is likely to be stronger than the aforementioned Sun-Mon system but cold just as easily be rain as snow from this far vantage point.
LARSON'S LONG-RANGE
Pattern Overview
Make no mistake about it, we are now into a pattern that will likely bring near to below-normal temperatures for the remainder of the month. A deep ridge southeast of Alaska will keep a strong trough of over the eastern two-thirds of the nation, allowing for cross-polar flow from Canada to drain polar air into our area. A caveat, however: with this general setup, my thinking is that while there is certainly potential for snow over the upcoming period, it is almost as likely that the storm track will be suppressed to the south of us, leaving DC high and dry. I also believe that over the next week our temperatures are much more likely to bust "cold" or lower than model guidance than the opposite, so I've gone lower than most other outlets.Pictured above: the GFS' representation of a deep trough over the eastern US much if not all of next week; courtesy Unisys.com.
Next week's forecast
Forecast highs/lows: 37/24 (normal = 42/27)
Forecast precip: Below normal??
Expect mostly cloudy skies on Monday with a chance of lingering snow showers; highs will be in the mid 30s with overnight lows in the mid 20s. More clouds than sun on Tuesday with a slight chance of flurries and highs in the upper 30s with lows in the low to mid 20s. Wednesday is likely to feature times of clouds and sun with highs from 35-40 and lows in the 20s. Thursday and Friday will feature mostly cloudy skies with a chance of rain or snow with highs from the low 30s to near 40 with overnight lows remaining in the 20s.
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