March 27-April 9, 2005 Pattern Discussion

[donsutherland1]

Last week’s discussion raised a number of issues of what one might expect for the March 20-April 2, 2005 period.

• Although one will likely see the cold ease in the Mid-Atlantic and Northeast starting late next week, readings through the rest of the month and into the first two days of April will probably average near or somewhat below normal for the period as a whole… In the longer range, moderation will likely occur in the closing days of March.

Through March 25, temperatures remained generally somewhat below normal in the Mid-Atlantic and Northeast. Moderation was forecast on the computer guidance, especially for the March 28-April 2 period.

• Parts of the northern Mid-Atlantic and southern New England, including Boston, will likely see some snow changing to rain Saturday night into perhaps early Monday. A modest accumulation is possible in Boston. Interior sections could see an appreciable snowfall.

During the March 24-25 period, an additional storm could move off the East Coast bringing rain to Washington, DC to Philadelphia and possibly rain or snow changing to rain to New York City and Boston. Behind the storm, a colder air mass should return for the weekend of March 26-27.

The March 20-21 period saw no accumulating snow in Boston. Interior sections picked up a little snow. A storm on March 23-24 brought snow that changed to rain in some places and ended as snow. Small accumulations occurred in New York City and Boston. Some inland areas picked up appreciable and even significant accumulations. In the wake of the storm, cooler air arrived.


• After a cool end to the weekend, temperatures should moderate across the Ohio Valley, Midwest, and Great Lakes region. Rain could affect this area during the March 23-24 period. The weekend should be somewhat colder before milder air returns.

The forecast for this area was generally poor with temperatures averaging mainly below normal. 3/23 saw 0.3” snow in Chicago and 1.7” in Detroit.

• The week of March 20-26 should see generally warmer than normal conditions across the Central Plains states. However, the March 19-20 period could see the risk of severe weather in parts of Texas and the Deep South. The March 22-23 timeframe could see a storm bring rain to such cities as Kansas City and St. Louis. The weekend looks to be somewhat cooler but readings could remain near or somewhat above normal.

The March 20-25 period saw temperatures average somewhat below normal in this region. Severe weather impacted parts of Texas and the Deep South during the March 19-20 timeframe. March 21-22 saw 0.31” rain in Omaha and 0.49” in Kansas City.

• At present, the March 19-21 period could see at least a moderate rainfall in the Seattle area. In the wake of this storm, temperatures should remain close to normal.

Seattle received 0.51” rain during the March 19-21 period. Following the storm, the March 22-25 timeframe experienced normal temperatures.

• Los Angeles will likely see additional rainfall next week during the March 22-24 timeframe. Readings should generally remain close to normal, though March 24 has the potential to be unseasonably cool. March should end on a dry and mild note.

Los Angeles picked up 1.08” rain on March 22. Readings averaged somewhat below normal as a cool shot brought unseasonably cool readings during the March 23-25 period. March 24 was the coolest day, averaging 7° below normal.

The March 27-April 9 Ideas:

The major story is that the GFS ensembles are pointing to the evolution of the NAO toward what increasingly appears likely to be a positive regime sometime during the first 10 days of April.

Things to keep in mind with regard to the NAO/PNA in April:

Positive NAO/Moderately Positive PNA: generally widespread warmth across the northern half of the United States. The Pacific Northwest and Northeastern U.S. are often wetter than normal.

Positive NAO/Moderately Negative PNA: generally cool across the Northeast; Warm in the Mid-Atlantic and Southeast. The western third of the United States is often warmer to much warmer than normal. In terms of precipitation, these periods typically see dry conditions in California, the Northern Plains, and the East. Texas is often quite wet.

• Overall, the next 10-14 days will likely see a transition toward springlike weather in the East. Precipitation will likely run above to much above normal given that the NAO and PNA should both be trending toward modestly positive levels. March 27-28 should see a widespread, heavy rainfall in excess of 1”. April 2-3 could see additional rain along with the passage of a cold front. April 5-7 could see another storm and this storm could bring some snow to parts of the Northeast with even Boston having some chance of picking up a modest accumulation. A longer-shot is New York City. There, if there is any snow, it would likely amount to less than an inch and probably little more than a trace. Afterward, cooler air will likely give way toward moderation which might mark the arrival of a springlike pattern.

The March 30-April 1 period will likely see warmer than normal to much warmer than normal readings in the Mid-Atlantic and Northeast. The temperature will likely exceed 60° in New York City and perhaps even Boston on at least one day during this stretch.

• Colder weather will likely give way to a shot of unseasonable warmth in the Great Lakes region and Midwest. On March 26, Chicago and Detroit could see a little wet snow. March 28-29 should mark the arrival of a brief period of unseasonably warm readings and it is possible that both Chicago and Detroit could see at least one 60° or warmer reading during the March 28-March 31 timeframe.

A cold front should bring cooler readings by April 1 along with some rain. April 4-5 should see additional precipitation and then the transition toward a more springlike pattern could commence by around April 8.

• Warmer than normal readings are likely in the Central Plains during the March 28-31 timeframe. Readings could surge into the 70s in both Omaha and Kansas City. A cold front should bring cooler readings on April 1. However, the cooler readings will likely be short-lived.

• A cool period appears to be on tap in Seattle. The shift toward a wetter pattern should continue. The March 26-27 period could see moderate or even heavy rain. Amounts will likely exceed 0.50”. Additional rain could occur during the April 1-2 timeframe. Readings will likely average cooler than normal through April 3. Some moderation is likely afterward.

• Even as the Pacific Northwest is cool, warmth is likely across California. Los Angeles could experience much above normal readings during the March 26-April 2 timeframe. Little or no rainfall is likely during that stretch.

Notable Late-Season Snowfalls of the 1850s:

• May 3, 1851:
Vermont: “The Vermont State Banner of the 10th inst., says: The mountains all around us are white with snow and have remained thus for a week past.” (Untitled, “The Brooklyn Daily Eagle, May 22, 1851.)

• July 3, 1854:
Vermont: “On the morning of July 3, the mountains east of Burlington, VT were covered with snow…” (“Phenomena of July, 1854, &c.,” The New York Daily Times, September 15, 1854.)

• May 7-8, 1855:
Avon, NY: “It commenced snowing here yesterday afternoon [May 7], and this morning the snow is three inches deep and still falling.” (“The Weather—Railroads and Incidents in Western New York,” The New York Daily Times, May 10, 1855.)

Buffalo: “The weather is very cold, and snow is now falling. The weather at Cleveland is the same [May 7].” (“Weather in Buffalo and Cleveland,” The New York Daily Times, May 8, 1855.)

• May 9, 1855:
Hazleton, PA: “Snow fell to the depth of four inches here this morning. It is now raining hard.” (“The Weather, Fruit Crops, etc.,” The New York Daily Times, May 10, 1855.)

• May 21, 1855:
Wells River, VT: “We are having here this morning, quite a severe snowstorm.” (“Snowstorm at Wells River, VT,” The New York Daily Times, May 22, 1855.)

• May 6, 1856:
Newburgh, NY: “There was quite a brisk flurry of snow at Newburgh at noon... The temperature was low during the whole day, with a sharp wind.” (“Fine May Weather,” The New York Daily Times, May 6, 1856.)

• May 30-31, 1856:
Northern New England: “At Bangor, Waterville and Danville, this morning [May 31], it was snowing, and the weather was very cold.” (“Snow at the Eastward,” The New York Daily Times, June 2, 1856.)

Pittsburgh: “Quite a heavy snowstorm is now (1 o’clock, P.M.) prevailing in this locality [May 30].” (“Snow Storm at Pittsburgh,” The New York Daily Times, May 31, 1856.)

• May 10-11, 1857:
Ogdensburg, NY: “Three or four inches of snow fell last night [May 10 into May 11], out towards Ogdensburg.” (“The Weather,” The New York Daily Times, May 12, 1857.)

• July 24, 1858:
Mount Washington, NH: “[S]oon after midnight a violent storm set in. The hail roared on the cabin-roof like grape shot. On coming out this morning we found the rocks covered with snow! The thermometer stood at 30°, and ice was formed on all the standing water.” (“Snow on Mount Washington in July,” The New York Times, July 29, 1858.)

March Snowfall Update:

On February 25, I stated, “Given the pattern likely to predominate the first half of March, I believe it is reasonable to expect that Boston will likely see 8” or more in March, NYC should see 6” or more, and Washington, DC 3” or more.”

Totals through March 25 came to:

Boston: 14.5”
New York City: 6.9”
Washington, DC: 0.8”

NOTE: After April, this discussion will appear only in the U.S. Weather Watch Forum until next fall.

[W13]

Great discussion, as usual Don!

Thanks for the heads up about the move of the discussion, too.

[donsutherland1]

Thanks for the kind words, W13.