Pattern Change Appears Imminent

[donsutherland1]

Early progress report, thoughts on the clipper...

November 1-15 Temperature Anomalies/Precipitation

Baltimore: +6.4°; 0.02”
Boston: +3.0°; 0.91”
New York City: +5.8°; 0.39”
Newark: +5.3°; 0.43”
Norfolk: +4.9°; 0.26”
Philadelphia: +5.7°; 0.35”
Providence: +3.8°; 1.01”
Richmond: +8.1°; 0.10”
Washington, DC: +5.6°; 0.06”

A week later, here's how things stand (November 1-22):

Baltimore: +3.7°; 1.46”
Boston: +2.0°; 3.04”
New York City: +3.5°; 2.65”
Newark: +3.1°; 2.48”
Norfolk: +2.7°; 3.43”
Philadelphia: +3.3°; 2.16”
Providence: +2.8°; 3.74”
Richmond: +5.1°; 2.94”
Washington, DC: +2.7°; 1.35”

Progress has been made. Warm anomalies have been sliced significantly over the past week. Even that "great fortress of warmth", Richmond, has seen its towering anomalies reduced.

That progress should continue. Toward the end of the month/first days of December, there should be moderation. However, it should be temporary and probably not extreme.

Already, the 11/23 12z GFS has backed off from that model's earlier attempts at a full-fledged beach party all the way to the shores of Boston's Charles River. The model now appears more reasonable given the ideas of the NCEP ensembles. Beyond 240 hours, I don't have high confidence in its solution, especially if blocking begins to grow more meaningful at some point afterward.

Finally, with regard to the upcoming 11/24 clipper, my ideas remain unchanged with regard to snowfall amounts but will note that odds favor the lower amounts for the big cities (Boston, NYC, Newark, and Providence):

Albany: 1”-2”
Boston: Coating to 1”
Hartford: 0.5” to 2”
New York City: Trace to perhaps a coating
Newark: Trace to perhaps a coating
Providence: Coating to 1”

[Jim Hughes]

Patterns like this are supposed to happen when you previously have extremes on the other side. The amplitude of the jet stream will end up swinging back 90 % of the time.

Only twice since 1879 has Reagan National Airport in Washington DC had a + 5.6 temperature anomaly in November. So when you see this type of anomaly at the halfway mark you can take it to the bank that it's going to flip flop just like it did last month....last December and last January.

Last month. First 20 days ... only two negative daily anomalies (-1.0, -1.0) ... four days > = + 10 degrees..... Eight out of next eleven below average.

October average +1.6 degrees.



Jim

[donsutherland1]

Final ideas on the November 23-24, 2005 clipper/possible windex event.

• Things seem to be proceeding a little faster than I had envisioned
• Readings are likely to be a few degrees cooler at the onset before the warmer air sweeps in
• The area of wintry precipitation is more expansive

Albany: 1”-3”
Baltimore: Trace to 0.5"
Boston: Coating to 1”
Hartford: 1” to 2”
New York City: Trace to 0.5"
Newark: Trace to 0.5"
Philadelphia: Trace to 1"
Providence: Coating to 1”
Washington, DC: Trace to 0.5"

As a result, it now appears that all of the major cities from Washington, DC to Boston will have seen some accumulation of snow (at least a trace) for November.

[donsutherland1]

Clipper Verification:

Forecasts:

From November 21, 2005 11 pm:
Albany: 1”-2”; Actual: 0.5"; Error: 0.5"-1.5"
Boston: Coating to 1”; Actual: Trace; Error: 0.1"-0.9"
Hartford: 0.5” to 2”; Actual: 3.3"; Error: 1.3"-2.8"
New York City: Trace to perhaps a coating; Actual: Trace; Within range
Newark: Trace to perhaps a coating; Actual: Trace; Within range
Providence: Coating to 1”; Actual: 2.0"; Error: 1.0"-1.9"

4 outside range; 2 within range

From November 23, 2005 8 pm:
Albany: 1”-3”; Actual: 0.5"; Error: 0.5"-2.5"
Baltimore: Trace to 0.5"; Actual: 0.5"; Within range
Boston: Coating to 1”; Actual: Trace; Error: 0.1"-0.9"
Hartford: 1” to 2”; Actual: 3.3"; Error: 1.3"-2.8"
New York City: Trace to 0.5"; Actual: Trace; Within range
Newark: Trace to 0.5"; Actual: Trace; Within range
Philadelphia: Trace to 1"; Actual: Trace; Within range
Providence: Coating to 1”; Actual: 2.0"; Error: 1.0"-1.9"
Washington, DC: Trace to 0.5"; Actual: Trace; Error: Within range

5 within range; 4 outside range

[donsutherland1]

Mini-verification...

From 11/21 11 pm:

In terms of temperatures, minimum temperatures could fall into the 20s as far south as Richmond. Teens in such cities as Albany and Burlington are possible.

Select lowest temperature for the 11/25-27 period are:

Boston: 22°
New York City: 26°
Philadelphia: 25°
Washington, DC: 25°

Actual lowest readings:

Albany: 17°
Boston: 21°
Burlington: 16°
New York City: 22°
Philadelphia: 22°
Raleigh: 25°
Richmond: 23°
Washington, DC: 22°

[wx247]

Conversation on the potential upcoming pattern change has "cooled off" some in the last few days. I heard one met talking last evening as if we were about to head into the deep freeze while one on another channel seemed to believe that the models had begun to shift their ideas. It is enough to make your head spin... that is for sure.

[Jim Hughes]

Conversation on the potential upcoming pattern change has "cooled off" some in the last few days. I heard one met talking last evening as if we were about to head into the deep freeze while one on another channel seemed to believe that the models had begun to shift their ideas. It is enough to make your head spin... that is for sure.

Are you referring to a pattern change that can last 3-5 days or 10-20 days ?



Jim

[wx247]

Conversation on the potential upcoming pattern change has "cooled off" some in the last few days. I heard one met talking last evening as if we were about to head into the deep freeze while one on another channel seemed to believe that the models had begun to shift their ideas. It is enough to make your head spin... that is for sure.

Are you referring to a pattern change that can last 3-5 days or 10-20 days ?



Jim

In the next 3-5. Our mets on air aren't committed enough to go beyond 7 days.

[breeze]

Neither are ours in the Nashville area, Garrett. The next
three months around here will be "a chance"..."probable"...
..."iffy"..."possibly"...

My Daddy always said that "even a turtle sticks his neck out,
sometimes..." Uh-uh...not mets around here...no way.

[donsutherland1]

On this date in 1921, New England was in the grips of an unforgiving ice storm. Today, milder breezes prevail and just to the south a distinct feel of early autumn is in the air.

Nonetheless, so far, the pattern discussion ideas continue to work out quite well. Some of the details, though, have not been as good as I would have liked.

On November 17, I noted, "Later, the final days of November might see temporary moderation, but the cold should return during the first week in December. As that week advances, I believe that the risk of an Arctic outbreak could be growing."

That's all right. The warmth has now overspread the Mid-Atlantic into southern New England. In parts of the Mid-Atlantic, it is quite impressive.

Some examples for high temperatures prior to 3 pm:

New York City: 62°
Newark: 63°
Philadelphia: 68°
Richmond: 73°
Washington, DC: 65°

On November 23, I added, "...a peak in the 50s is probably more reasonable [for Boston]. I still believe that the warmup will not turn into a prolonged, fiery (relative to normal) agony that stretches through much of the month with only small intrusions of modest chill."

Boston will likely reach the high 50s. 60° can't be altogether ruled out.

Overall, I believe that I downplayed the magnitude of the warmth. DT has done outstanding on pointing out the magnitude of the warmth now in place. In fact, he has done very well with such events on a regular basis, including the spectacular warmth of early January 2005. So, in coming days, I'll look back at some of his posts for better insight with regard to such outbreaks of warmth.

In any case, the cold should be returning later this week.

The idea of a stormy pattern still looks very good. Another soaking rain is likely later tomorrow into Wednesday for the Mid-Atlantic/Northeast. This rainfall should bring NYC to 50.00" or more precipitation for a record-tying 3rd consecutive year. The Ohio Valley could see some snow from this system. Even Pittsburgh might experience a little snow at the tail-end as it pulls eastward.

Afterward, there is decent model support for a system to bring precipitation later this weekend/early next week. There is the possibility that this system could bring snow or snow changing to rain to some of the coastal areas and mainly or wholly snow inland. With a progressive pattern, I'm not thinking that this will turn into a major coastal storm.

With NYC having received a trace of snow in November, if 10" or more were to fall in December, the pattern could well be signaling a 4th consecutive snowy winter. Since 1869-70, 17/19 (89%) winters that saw a trace of snow in November and 10" or more in December had 30" or more seasonal snowfall.

Finally, late in the first week in December through December 10, it appears possible that an Arctic air mass could push into the United States and reach the East. With the Arctic Oscillation likely to tank per the ensembles (a cluster disagrees) and the NAO now progged to stay negative (its predominant state since November 15 (11/14 days have seen a negative NAO), I have growing confidence that there should be sufficient blocking to force colder air into the U.S. Such a situation should enable the first 10 days of the month to average at least below normal from Richmond to New England. The pattern could remain blocky through at least mid-December. Hence, my confidence in a month that ends up at least somewhat colder than normal has increased in recent days.

For now, though, autumn's warmer side is staging a counterattack. But even as temperatures spike in parts of the East, mainly south of New England, winter will not be vanquished.

[donsutherland1]

Verification:
Through November 30

A return to storminess in the East.
Storminess returned to the East. The second half of November saw the following precipitation amounts:

Baltimore: 2.10"
Boston: 2.80"
New York City: 4.08"
Newark: 3.31"
Norfolk: 3.53"
Philadelphia: 2.51"
Providence: 4.59"
Richmond: 3.71"
Washington, DC: 1.86"

First freeze, perhaps as far south as Washington, DC, in the November 20-30 timeframe. Boston and Providence might see at least one low below 30° before the end of the month.

Temperatures bottomed out in the lower 20s from Richmond to Boston. Lowest readings were:

Albany: 17°
Boston: 21°
Burlington: 16°
New York City: 22°
Philadelphia: 22°
Raleigh: 25°
Richmond: 23°
Washington, DC: 22°

Those readings were colder than anticipated at the beginning of this thread but were reasonably in line (mainly within 3°) with an 11/21 update

November 20-30 averages somewhat below normal from Philadelphia to Boston.

Temperatures were near normal, though a little warmer than anticipated. November 20-30 average anomalies were:

Boston: -0.5°
New York City: +0.3°
Philadelphia: -0.7°
Providence: +0.8°

4-City Average: -0.1°

At least one event prior to November 30 where rain ends as snow in coastal sections of the East, particularly from Philadelphia north and eastward.

Snowfall totals were:

Baltimore: 0.5"
Boston: Trace
New York City: Trace
Newark: Trace
Norfolk: 0.0"
Philadelphia: Trace
Providence: 2.0"
Richmond: 0.0"
Washington, DC: Trace

The following points will be verified after December 10:

∙ December 1-10 averages below normal to perhaps much below normal from Richmond to Boston.

∙ Possible major storm in the period beginning near Thanksgiving Day to around December 5. Per Heather Archambeault’s research, there may be an ensemble signal for such an event.

∙ Growing risk of a significant Arctic outbreak during the first week of December.

[donsutherland1]

Verification of Remaining Points:

∙ December 1-10 averages below normal to perhaps much below normal from Richmond to Boston.

December 1-10 Temperature Departures from Normal:
Baltimore: -7.3°
Boston: -5.9°
New York City: -7.2°
Newark: -7.3°
Philadelphia: -5.4°
Providence: -7.1°
Richmond: -5.9°
Washington, DC (DCA): -8.0°

∙ Possible major storm in the period beginning near Thanksgiving Day to around December 5. Per Heather Archambeault’s research, there may be an ensemble signal for such an event.

A snowstorm brushed the coast on December 5-6. Another storm intensified explosively off southern New England on December 9.

∙ Growing risk of a significant Arctic outbreak during the first week of December.

Many of the East Coast cities saw their coldest readings of the season so far just after the first week in December. Arctic cold covered the Midwest late in the first week of December. The December 5-8 period saw the mercury fall to single digits on each day in Chicago. The lowest was 0° on December 7. The December 6-8 period saw single-digit lows in Detroit on each day with a low of 6° on December 8.

Lowest temperatures in the East were:

Baltimore: 18°, December 7, 8
Boston: 19°, December 8
New York City: 22°, December 8
Newark: 21°, December 8
Philadelphia: 20°, December 8
Providence: 19°, December 8
Richmond: 22°, December 7
Washington, DC (DCA): 23°, December 8

[AnthonyC]

Hey Don!

You got any thoughts for the PNW? Latest models start retrogression bringing colder than normal temps to the PNW. What are your thoughts?

Anthony

[donsutherland1]

Anthony,

In the next day or so, I'll post an updated pattern discussion for the rest of the month and will touch on the Pac NW.