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• Per analogs and model guidance, look for generally seasonal temperatures to arrive in the February 1-3 period [in the East. This does not mean that it cannot snow, especially from Philadelphia northward through the first 10 days of February. However, one should not expect severe cold during this timeframe.
Overall, February 1-10 should average near normal. However, a cooling trend could be getting underway near or just after February 10. The February 3-7 period should probably see above normal readings with highs in the 40s in Boston and New York City. Through February 5, I don’t believe either city will see significant snowfall.
So far, the idea of a temperate period appears to be working out quite well. No severe cold appears likely through February 10. In addition, no significant snow has occurred in the I-95 Corridor from Philadelphia to Boston through February 4 and none is likely through the February 5 date mentioned in the last pattern discussion. Washington, DC, parts of Virginia, Maryland and North Carolina saw a minor accumulation of snow on February 3. At the same time, the idea of milder readings also looked good. On February 3, the temperature reached 41° in NYC. 40s appeared likely from the weekend through at least the middle of next week before the colder pattern set in.
• Across the Deep South, readings should remain generally below normal to near normal through February 3. Afterward, just as the milder air begins to approach its high tide in the Northeast and Mid-Atlantic, also look for warmer readings across the Deep South.
Parts of northern and central Georgia into the Carolinas experienced an ice storm during the January 28-30 period. The January 30-February 3 period saw temperatures average below to much below normal across this region. However, milder readings appeared likely heading into the weekend.
• The Central Plains will see temperatures running near or somewhat above normal through February 2. However, a cooling trend could occur afterward and such cities as Omaha could pick up accumulations of snow before next week is out. The highest risk of snow is probably in the February 3-5 period.
Temperatures were running above normal, and in a few places, much above normal as January ended and February began. Per latest model guidance, it appears that the idea of a return to colder weather and then the threat of snow was predicted a few days early. It appears that the colder weather should return in the February 5-6 period with snow possible later in that period.
• For the January 23-31 period, Seattle might see its coldest reading in the 27°-32°.
The lowest reading proved higher than I had anticipated. It came to 37° on January 25.
• The current cooler weather in the Pacific Northwest will likely last until around February 1. Afterward, as a new ridge begins to build, readings will be on the rise and Seattle could again see highs in the middle 50s by February 3.
Through February 1, temperatures averaged between 3°-6° above normal in Seattle. Although this had been a cooler period, it was relatively mild. By January 31, maximum temperatures were pushing toward the middle 50s. The temperature surged to 59° on February 2, so the timing for the height of the warmth was off by a day.
The February 6-19 Ideas:
In spite of some recent uncertainty in the computer guidance, namely its recent retreat from a return to winter scenario, I believe the pattern change for around February 10 remains well on course. Putting aside arguments that were made in past pattern discussions, another factor that argues for the possible return of a negative NAO is the MJO. Currently the MJO is in Stage 6. Within 8-12 days, it should be at Stage 8. Stage 8 has often had a tendency for a negative NAO and a trough in the eastern half of the United States:
Another argument for the return of cold is the recent 500 mb height anomalies. For five consecutive days (January 30-February 3), above normal height anomalies were linked across North America out toward Western Europe. Such a linkage when sustained for several days has, in the past, sometimes preceded major Arctic outbreaks. Finally, the objective analogs put out by CPC also point to a possible change toward a return of wintry weather during the period centered around February 15.
Given the changes taking place, I believe the next two weeks will likely see:
• From Washington, DC to Boston, temperatures will run near to somewhat above normal to around February 10-11 (with the 11th being a day later than identified in last week’s pattern discussion). Afterward, temperatures will run somewhat below normal until around mid-month. Then, the potential exists for temperatures to shift to much below normal after mid-month.
After February 10, the threat of accumulating snow will increase. I expect that there will be accumulations in both New York City and Boston before mid-month. And, the threat of a possible major storm from the Mid-Atlantic to New England might be on the increase after February 14. Given the return of cold air, a more active southern jet, and some hints among the ensembles, this is a matter that will bear watching.
• February 9-10 should see the return of accumulating snow in the Midwest and Ohio Valley. Chicago, Detroit, and Cleveland should all see accumulations. Some rain prior to the change to snow cannot be ruled out. At the same time, I would not be surprised if at least one of these cities, particularly Detroit or Cleveland has a chance at a significant snowfall of 6” or more. Early the following week (week of February 13) could see a renewed shot of cold air, perhaps colder than the shot that follows the aforementioned threat of snow.
• The Southeast will likely see a cooling trend commence around February 10, as well. However, the prospects for snow and ice probably won’t increase markedly until after mid-month when the pattern could become more suppressed. Such a development could occur after the aforementioned possible big storm in the East. Before then, midweek (around February 8-9) it is entirely possible that parts of the Southeast, including Atlanta, could see thunderstorms before colder air returns.
• The Plains states will be a battleground between milder air and much colder air. The first surge of cold air should arrive around February 8-9. Precipitation could end as snow in such cities as Kansas City and Omaha. Although temperatures could moderate near or during the weekend, another shot of cold air could arrive early the following week.
• A noticeably wetter pattern could develop across California beginning in the February 14-17 timeframe and that pattern could persist for at least a week. This wetter pattern should spread east to Texas during the February 16-19 timeframe and should also persist for at least a week.
• February 6-9 should see temperatures remain below normal across the Pacific Northwest. Seattle could see the temperature slip below freezing on one or more days during this timeframe. Some snow showers are possible on February 6. By midweek, a slow moderating trend should get underway as the trough heads eastward. After mid-month, temperatures likely will be running above normal in the Pacific Northwest.
Summer/Hurricane Season Peek:
From this vantage point, and much can still change, it appears that Summer 2005 will be much different from Summer 2004. If the data holds up, the eastern two-thirds of the United States will likely see a warmer than normal summer. The western third should be near normal but the Pacific Northwest might be on the cool side, though the Desert Southwest could be warmer than normal. Depending on which analogs rise to the forefront as summer nears, there is the chance that the eastern two-thirds of the nation could actually see a hot summer with some episodes of high heat. Right now, it is still too soon to make such a call on whether the summer could be hot. But it does look very different from last summer.
The 2005 hurricane season promises to be another active one. However, it might be somewhat less active than 2004. A higher than normal percentage of named storms should develop into hurricanes. Moreover, a larger than normal percentage of hurricanes should reach major status. At this point in time, early indications are that the season could have a classic profile for above normal major hurricane activity (average of 4.2 per season in those that met such criteria). 8 of 9 (89%) of seasons that met such criteria saw 3 or more major hurricanes.
The PDO could be a critical player. If the PDO averages positive during the 2005 hurricane season, the potential would then be in place for possible excessive major hurricane development (last season met this profile). If not, such development should be above normal. For now, I’m taking the more conservative route, especially as the PDO has had a negative tendency over the past few months. Whether any major hurricanes threaten U.S. landfall is another issue, but that will be examined more closely in a few months (probably early April). For those who desire to know right now, signals are mixed but there is a significant cluster of analogs where such hurricanes made U.S. landfall. Until it becomes clearer as to which analogs are proving strongest, it’s too soon for me to make such a call.
Finally, in another thread, Luis (Cycloneye) observed that the tropical Atlantic is unseasonably warm at this point in time. This could be another hint that reinforces the early analog idea of another active hurricane season.
The December 2004 Tropical North Atlantic Index (TNA) was the highest on record for December at +0.75. FWIW, there were four previous years when the TNA came to +0.40 or above in December and 7/8 (87.5%) had 10 or more named storms in the following hurricane season:
Named Storms:
1953: 14
1963: 9
1970: 10
1988: 12
1996: 13
1998: 14
2002: 12
2004: 15
Average: 12.4
Even more disturbing just as a cluster of emerging analogs pointed to the risk of a major hurricane making landfall, the same held true from the above-noted seasons.
