{"id":9306,"date":"2016-03-19T16:00:18","date_gmt":"2016-03-19T20:00:18","guid":{"rendered":"http:\/\/ezweather.com\/myblog\/?p=9306"},"modified":"2016-03-20T16:12:24","modified_gmt":"2016-03-20T20:12:24","slug":"donald-sutherland-winter-weather-column-december-updates-3","status":"publish","type":"post","link":"https:\/\/www.ezweather.com\/myblog\/2016\/03\/19\/donald-sutherland-winter-weather-column-december-updates-3\/","title":{"rendered":"Donald Sutherland – Winter Weather Column (March Updates)"},"content":{"rendered":"

Hi Everyone,
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Its that time of year again and I’m looking forward to starting this blog again. \u00a0Donald Sutherland, who posts over at American Weather Forums does a great job in providing some insight toward future winter weather patterns. \u00a0\u00a0I’ll continue to update this periodically the next several months.<\/span><\/p>\n

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Posted 19\u00a0March 2016 – 6:19 PM<\/abbr><\/span><\/strong><\/p>\n

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Some of the computer guidance, including the 3\/19\/2016 12z GGEM, RGEM and UKMET; 3\/19\/2016 12z EPS; and, 3\/19\/2016 18z GFS and RGEM indicate that a storm will bring a swath of potentially 4\u201d or more snow from portions of the northern Middle Atlantic region into New England.<\/span><\/p>\n

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Since 1950, there have been 20 such storms. Two of those storms brought 4\u201d or more snow to Boston and New York City while one of those storms brought 4\u201d or more to New York City and Philadelphia.<\/span><\/p>\n

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Posted 4\u00a0March 2016 – 1:39 PM<\/abbr><\/span><\/strong><\/p>\n

Last night into today, a storm moving off the lower Mid-Atlantic coast deposited a swath of snow across the Middle Atlantic region. For the most part, snowfall amounts were fairly light (2″ or less). However, a few locations saw greater amounts including Cape May, NJ: 6.5″; Milton, DE: 5.8″; and, Princess Anne, MD: 6.7″.<\/span><\/p>\n

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Big changes lie ahead on account of the expected development of an extreme trough centered near Mexico’s Pacific Coastline (more than 5 standard deviations below normal) and a ridge with positive height anomalies of 1-2 standard deviations above normal in the East during the 3\/8-10 period. The result should be the warmest readings so far this year in parts of the Great Lakes Region to the Middle Atlantic and New England areas.<\/span><\/p>\n

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Posted 29\u00a0February 2016 – 10:19 AM<\/abbr><\/span><\/strong><\/p>\n

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Today’s AO figure was -0.378. Based on the final December and January values and preliminary February values, the AO was neutral to slightly positive for Winter 2015-16. The preliminary average is +0.007.<\/span><\/p>\n

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The distribution of values is below:<\/span><\/p>\n

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With the wave lengths continuing to shorten courtesy of the seasonal evolution, one needs stronger blocking, all other variables being equal, to produce the cold anomalies similar to those in February. For example, for New York City, the March 1-10 temperature anomalies for an AO of -2.999 to -0.001 is similar to those for an AO > 0. An AO of -3.000 or below is decidedly cooler (nearly 6\u00b0 cooler).<\/span><\/p>\n

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\"AO02262016.jpg\"<\/p>\n

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One variable that could offset a positive AO is the EPO. Last March, the EPO was negative to strongly negative for much of the first 20 days of the month. This March, it is forecast to be positive through at least the first 10 days of the month. At the same time, the AO is forecast to bottom near -2.000 before rising toward possible positive values by March 10.<\/span><\/p>\n

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Just looking at the state of those two indices and typical 500 mb patterns associated with them would argue for a warming trend to roll across the CONUS near March 7 +\/- a few days with the potential for a bout of much above normal readings. There remains a risk that the second half of the month could witness the development of sustained ridging covering parts of eastern North America including Ontario, Quebec, the Midwest, Mid-Atlantic, and New England areas. If so, the second half of the month could be very warm relative to normal. Such ridging developed in late March in 1998 as a super El Ni\u00f1o was winding down. For now, it’s a little soon to be sure about such an outcome this March, but the potential is there, especially if blocking dissipates and does not rebuild.<\/span><\/p>\n

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For now, my guess is that a large part of the Midwest and eastward will probably wind up experiencing a much warmer than normal month (anomalies of 3\u00b0 or more above normal). The PDO+ will likely continue to promote a PNA+ pattern, which would bring continued warmer than normal readings to the Pacific Northwest.<\/span><\/p>\n

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Posted 23\u00a0February 2016 – 11:18 AM<\/abbr><\/span><\/strong><\/p>\n

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During the November 19-22, 2015 period, a significant early season storm brought heavy snow across parts of the Midwest into the Great Lakes region. Chicago picked up 11.2\u201d and Detroit received 6.0\u201d. Howell, MI was buried under 15.5\u201d.<\/span><\/p>\n

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An even stronger storm will bring heavy snow to the south and east of the November storm\u2019s axis of heaviest snows. As a result, parts of northwestern Indiana into Michigan will likely see the biggest accumulations. The 12z run of the RGEM suggests the potential for 10\u201d or more snow exists in parts of that region.<\/span><\/p>\n

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At the same time, unseasonably warm air appears very likely to surge up the Eastern Seaboard. During the November storm, temperatures rose into the 50s as far north as southern New England with middle 50s reported in such cities as New York and Philadelphia. The push of warm air could be stronger this time around on account of the greater forecast intensity of the storm. As a result, it still appears likely that Baltimore, Richmond, and Washington could see temperatures reach or exceed 60\u00b0. Readings of 70\u00b0 or above are possible from parts of Virginia southward. Temperatures in the 50s could reach as far north as Portland, Maine. Moreover, parts of the Coastal Plain could pick up 1.50\u201d-3.00\u201d precipitation over the next 60 hours.<\/span><\/p>\n

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The 12z GFS MOS forecast highest temperatures for the 2\/24-25 period for select cities are:<\/span><\/p>\n

Baltimore: 60\u00b0<\/span><\/p>\n

Boston: 52\u00b0<\/span><\/p>\n

Bridgeport: 51\u00b0<\/span><\/p>\n

Charleston, SC: 77\u00b0<\/span><\/p>\n

New York City: 57\u00b0<\/span><\/p>\n

Newark: 56\u00b0<\/span><\/p>\n

Norfolk: 70\u00b0<\/span><\/p>\n

Philadelphia: 58\u00b0<\/span><\/p>\n

Portland: 51\u00b0<\/span><\/p>\n

Providence: 51\u00b0<\/span><\/p>\n

Raleigh: 72\u00b0<\/span><\/p>\n

Richmond: 71\u00b0<\/span><\/p>\n

Savannah: 78\u00b0<\/span><\/p>\n

Washington, DC: 62\u00b0<\/span><\/p>\n

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Posted 19\u00a0February 2016 – 10:19 AM<\/abbr><\/span><\/strong><\/p>\n

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The February 19 preliminary Arctic Oscillation figure was +1.609 bringing the winter-to-date AO average to +0.057. With today’s being the 46th AO+ day, winter 2015-16 is assured to have more than 50% of days with AO+ values. Even as the ensembles take the AO negative next week, somewhere close to 55% of days during winter 2015-16 will wind up with AO+ values. It remains likely that the winter AO average will also be somewhat positive unless the ensemble members showing the deeper blocking verify.<\/span><\/p>\n

At present the AO will likely be shifting negative around the 2\/24-25 timeframe. About half of ensemble members are negative at that time and around half are positive.<\/span><\/p>\n

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\"AO02192016.jpg\"<\/p>\n

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As that is happening, the computer guidance is in good agreement about the development of a potentially significant storm. Assuming the AO forecast is reasonably accurate, the timing of the development of the blocking will probably be a little late to promote the kind of storm that could bring a significant snowfall from Washington, DC to Boston. Instead, interior sections with perhaps those somewhat to the south and east of the heaviest snowfall during the February 15-16 storm would more likely be favored. Some snow could not be ruled out for the coastal plain, but the focus of heavier snows would be inland.<\/span><\/p>\n

With March approaching, it makes sense to examine how the AO has evolved relative to past strong El Ni\u00f1o winters. The closest match for the 15-day period ending February 25 is 1998.<\/span><\/p>\n

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\"AO02192016_2.jpg\"<\/p>\n

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March 1998 featured a persistent trough in eastern North America that gradually shifted south and westward after mid-month. The closing portion of March saw the development of a ridge over the eastern CONUS and trough along the West Coast.<\/span><\/p>\n

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There was also a close match with respect to the PNA. February 1998 saw 26 of 28 days with a PNA+. So far, February 2016 has had 17\/19 days with PNA+ values and, if the ensemble forecasts are correct, would wind up with 27\/29 days of PNA+ values. Both winters featured a strong and persistent PDO+, which favors the PNA+. March 1998 featured predominantly PNA+ values, with 27 of 31 days having such values. The closing 10 days of March saw the only PNA- values.<\/span><\/p>\n

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Some differences should be noted, as well.<\/span><\/p>\n

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1. The current strong El Ni\u00f1o is basinwide and experiencing the strongest cooling in the eastern ENSO regions; 1997-98 was an East-based ENSO event. During that event, Regions 3.4 and 4 were cooling faster than Region 1+2.<\/span><\/p>\n

2. The current guidance forecasts somewhat earlier development of blocking than during late February 1998.<\/span><\/p>\n

3. The current guidance forecasts that the blocking will be stronger than that which occurred from the end of February into March of 1998.<\/span><\/p>\n

4. Much higher amplitude MJO during February<\/span><\/p>\n

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So, at this point in time, one can cautiously argue for the development of a trough in eastern North America and possibly a fairly deep one. This trough could persist through at least the first 10-15 days of March. Then, at some point, it could weaken and\/or migrate westward. Much will depend on the strength of the forecast blocking and its evolution.<\/span><\/p>\n

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For now, it’s still a little soon to be sure, but there would be a risk of a dramatic pattern change late in the month. Before then, the active subtropical jet should provide periodic opportunities for frozen precipitation from the Plains States eastward to the Middle Atlantic and New England regions.<\/span><\/p>\n

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It should be noted that the latest CFSv2 begins to develop ridging in the East during week 4. That could be premature, but something that would be plausible during Week 5 or 6 if the evolution of blocking is reasonably similar to what took place in 1998 while allowing for stronger and somewhat longer-lasting blocking. The biggest uncertainty concerns the MJO. During March 1998, the big change to ridging occurred when the MJO moved in Phases 1 and then 2. Phase 2 closed the month and it was the only high-amplitude MJO during March. Assuming the MJO remains at predominantly high amplitudes as has been the tendency this winter (average amplitude through 2\/17: 1.747 vs. DJF 1997-98 figure of 1.113), MJO forcing will play a larger role in shaping the outcomes.<\/span><\/p>\n

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Posted 16\u00a0February 2016 – 11:19 PM<\/abbr><\/span><\/strong><\/p>\n

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To illustrate the potential extremes of the upcoming warmth in parts of the Plains States, the 2\/17 0z GFS MOS forecasts a high temperature of 81\u00b0 for Rapid City on February 18. That would smash the existing record of 66\u00b0, which was set in 1983. It would also be the earliest 80\u00b0 reading on record by 3 weeks, if it verifies.<\/span><\/p>\n

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Posted 16\u00a0February 2016 – 9:43 AM<\/abbr><\/span><\/strong><\/p>\n

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Record Heat Likely in the Plains\u2026<\/span><\/p>\n

What has been a winter of extremes continues. So far highlights include:<\/span><\/p>\n