2013 Fall Medium Range Discussion

[donsutherland1]

Don,

 

When the Climate Prediction Center issued its forecast for March on February 28, I noted that, in their reasoning, they gave little credence to using the AO (among others) as a predictive tool:

 

 

But you've plainly shown over the past two weeks and again over the past few winters that substantially negative AO values are useful as a leading predictor for temperatures in the eastern U.S.  Any thoughts on why they'd dismiss something that seems to useful?

I believe CPC was actually suggesting that it is difficult to predict the PNA, AO, and NAO over an extended timeframe. Toward two weeks, the dynamical models have a weaker performance. In cases, statistical data can add insight.

[ApacheTrout]

I believe CPC was actually suggesting that it is difficult to predict the PNA, AO, and NAO over an extended timeframe. Toward two weeks, the dynamical models have a weaker performance. In cases, statistical data can add insight.

Yes, I see now how it could be interpreted that way.

[donsutherland1]

Yes, I see now how it could be interpreted that way.

The reason I interpreted it as such is because CPC wrote, "...AND THE PACIFIC NORTH AMERICAN (PNA) PATTERNS - WHICH AFFECT THE TEMPERATURE ANOMALY PATTERN ESPECIALLY DURING BOREAL WINTER..."

 

It should be noted that the correlations decline during the spring, as wave lengths shorten. Nevertheless, strong blocking can still have an impact in April. However, statistically the odds favor a somewhat positive AO for April as a whole, even if early month blocking develops or redevelops.

[donsutherland1]

March Pattern Evolution On Track for Possible Plains Snowstorm...

 

Back on 2/26 (#652) when Kansas City was in the midst of a snowstorm that would wind up that city's 13th biggest on record with 11.0" snow, I noted with respect to March:

 

Later in the month, perhaps in a fashion not dissimilar from how the pattern evolved in March 2009, I suspect that the Plains States could again be at risk of a significant snowfall.

 

With 20.5" snow in February, Kansas City had its second snowiest February on record. The record is 20.7", which was set in 1960. To date, Kansas City has seen only a trace of snow in March despite the month's running a temperature anomaly of 4.3°F below normal. One of the non-accumulating snowfalls occurred on March 16, just a day after the temperature topped out at a toasty 83°.

 

The March snow drought appears poised to end. There is growing model consensus that a storm that will bring snow across the Plains States could bring a moderate to significant snowfall to some of the affected areas. Some of the guidance is currently suggesting that Kansas City could pick up 3"-6"/4"-8" snow on Saturday-Sunday (3/23-24). Such a storm would further highlight what has become a snowy winter compressed into two months (something to which those living in such cities as Boston and Worcester can relate).

 

Currently, Kansas City's snowfall to date of 25.2" is above the norm of 18.8" for seasonal snowfall. That ranks 37th highest. A figure at or above 30" for winter 2012-13 is a realistic possibility.

[GaWx]

AO Falls Below -5.000...

 

The Arctic Oscillation stood at -5.632 today. That's, by far, the lowest reading ever after March 15. It's also the lowest reading after March 6 (when the AO was -6.114 in 1970).

 

This is lowest AO since the -5.821 of 12/21/2009. Prior lower AO's were 1/18-19/1985, 1/12-17/1977, 3/4-6/1970, and 11/18/1959.

[mrgolf]

This msg is for don sutherland, but anyone can chime in if they want. I will agree, it has been colder since the beg-middle of feb for east of rocky mtns. I live around memphis tn and unfortunately we didnt see much of any snow or ice. Not sure why that happened. Did the pacific have some influence to allow the fast zonal or progressive type pattern we have been in for a while now and not allow any systems to form in gulf where we usually see our winter storms? When the mjo got in its more favorable phases, which are 8 and 1 for cold and snow and ice chances, it seemed to me like the timing was incredibly off. I just wanted to know why the south perhaps didnt see much winter weather, despite a more favorable pattern with occasional ridges off west coast and a AO and NAO that was predominately negative most of the winter, especially as of late. Thanks kevin

[donsutherland1]

This msg is for don sutherland, but anyone can chime in if they want. I will agree, it has been colder since the beg-middle of feb for east of rocky mtns. I live around memphis tn and unfortunately we didnt see much of any snow or ice. Not sure why that happened. Did the pacific have some influence to allow the fast zonal or progressive type pattern we have been in for a while now and not allow any systems to form in gulf where we usually see our winter storms? When the mjo got in its more favorable phases, which are 8 and 1 for cold and snow and ice chances, it seemed to me like the timing was incredibly off. I just wanted to know why the south perhaps didnt see much winter weather, despite a more favorable pattern with occasional ridges off west coast and a AO and NAO that was predominately negative most of the winter, especially as of late. Thanks kevin

 

The timing was certainly off. The general lack of GOM systems hurt the TN Valley, as well as most of the Mid-Atlantic and Southeast. Redeveloping systems typically favor areas farther north. I suspect that the larger-scale drought might also have had some influence, though it's difficult to know how great that influence was. As the winter progressed, snowfall increased in such cities as Kansas City and Chicago. Unfortunately, areas to the south and east of that general area didn't enjoy the increase in snowfall.

 

Consequently, there is a sharp difference in seasonal snowfall totals. Two examples:

 

Nashville-Louisville-Dayton:

Nashville: 1.3" Much below normal

Louisville: 9.1" Below normal

Dayton: 27.5" Above normal

 

Philadelphia-New York City-Bridgeport:

Philadelphia: 7.2" Much below normal

New York City: 26.1" Above Normal

Bridgeport: 64.3" Much above normal

[GaWx]

This msg is for don sutherland, but anyone can chime in if they want. I will agree, it has been colder since the beg-middle of feb for east of rocky mtns. I live around memphis tn and unfortunately we didnt see much of any snow or ice. Not sure why that happened. Did the pacific have some influence to allow the fast zonal or progressive type pattern we have been in for a while now and not allow any systems to form in gulf where we usually see our winter storms? When the mjo got in its more favorable phases, which are 8 and 1 for cold and snow and ice chances, it seemed to me like the timing was incredibly off. I just wanted to know why the south perhaps didnt see much winter weather, despite a more favorable pattern with occasional ridges off west coast and a AO and NAO that was predominately negative most of the winter, especially as of late. Thanks kevin

 

mrgolf,

Being in the SE, I'll try to answer this:

 1) Just being in the south means that any given winter could easily be void of much wintry precip., regardless of the indices. Atlanta gets a major winter storm (S, IP, or ZR) only about once every two winters or so on average. Much of the cold in the SE is dry because the winds that bring in that cold are often pretty dry.

 

2) Not having El Nino reduces the chances for a Gulf low to form due I assume to a less prominent subtropical jet. I'm guessing that the -PDO, though not real strong, may reduce the chance for a Gulf low to form to some extent..

 

3) My own analyses have shown that the MJO's so-called favorable phases are pretty much irrelevant to the chance for a major winter storm in Atlanta and Raleigh. Granted, I didn't do that study for Memphis.

 

4) The NAO was actually mainly + in Jan./early Feb. However, it has since been mainly -.

[donsutherland1]

Cold start to April Appears Increasingly Likely for Plains States eastward...

 

Even as the record-breaking late-season block is forecast to fade by the start of April, it will likely take some time for the atmosphere to respond. Moreover, there remains a chance that a short-duration blocking episode could develop at a time when the PNA could be positive. Hence, odds likely favor a colder than normal start to April in the eastern half of the U.S. Over time, the cold anomalies could retreat to the Plains States, prior to a warmer pattern's taking hold.

 

At this time, among the top analogs based on ENSO and the teleconnections is 2009. That year featured cold anomalies for the first half of April. The second half saw widespread warm anomalies. It should be noted that there are larger than normal differences among the analogs in the pool. For example, one analog is generally warm (1969), but it ranks well below 2009 in my pool at this point in time.

 

Below is a chart that shows the composite anomalies for the first half of the month from my analog pool, the composite anomalies from the objective analogs centered on March 31, and then the 4/1-15 and 4/16-30 periods in 2009.

 

 

[andyhb]

2009 was a pretty quiet year for severe weather, that said, April of that year was above average due to a pretty impressive train of systems coming off the Pacific throughout the month, although there wasn't an extremely notable event other than the Good Friday Outbreak on 4/9-11 that spawned 21 significant tornadoes including 9 EF3s and an EF4 tornado in Murfreesboro, TN, among others.

 

That said, I'd be rather interested in another pattern setting up like that month.

[uncle W]

Cold start to April Appears Increasingly Likely for Plains States eastward...

 

Even as the record-breaking late-season block is forecast to fade by the start of April, it will likely take some time for the atmosphere to respond. Moreover, there remains a chance that a short-duration blocking episode could develop at a time when the PNA could be positive. Hence, odds likely favor a colder than normal start to April in the eastern half of the U.S. Over time, the cold anomalies could retreat to the Plains States, prior to a warmer pattern's taking hold.

 

At this time, among the top analogs based on ENSO and the teleconnections is 2009. That year featured cold anomalies for the first half of April. The second half saw widespread warm anomalies. It should be noted that there are larger than normal differences among the analogs in the pool. For example, one analog is generally warm (1969), but it ranks well below 2009 in my pool at this point in time.

 

Below is a chart that shows the composite anomalies for the first half of the month from my analog pool, the composite anomalies from the objective analogs centered on March 31, and then the 4/1-15 and 4/16-30 periods in 2009.

 

2009 had some hot weather the end of April...NYC had it's hottest temp of the year inlate  April...The Summer was quite cool until August...

[donsutherland1]

2009 had some hot weather the end of April...NYC had it's hottest temp of the year inlate  April...The Summer was quite cool until August...

I believe 2009 shows the kind of scenario of a sharp turnaround that could occur. Other analogs are more restrained, but most seem to indicate warmer anomalies for the second half of April. I'm not sure whether 2009 will be a good summer analog.

[uncle W]

I believe 2009 shows the kind of scenario of a sharp turnaround that could occur. Other analogs are more restrained, but most seem to indicate warmer anomalies for the second half of April. I'm not sure whether 2009 will be a good summer analog.

some analogs i'm looking at had a warm May...1965 included but after a cool April...

[donsutherland1]

Morning thoughts...

 

In the midst of a record-setting blocking late-season blocking regime, the AO was -5.298 this morning, marking the 3rd consecutive day on which the AO was at or below -5.000. The AO reached bottom on March 20 with a reading of -5.632. The ensemble guidance is in strong agreement that the blocking will relax and the block will retrograde in coming days. However, consistent with some of the analog guidance that suggested the possibility of a short-duration blocking regime for April, a growing number of ensemble members are indicating early April blocking. A few members keep the AO negative through the forecast period.

 

At this time, it appears that my thoughts for April (#731) may be on track. Specifically, the first half of April could see cold anomalies from the Plains States eastward. With the cold, there might be some additional opportunities for late-season snowfall. Cities such as Albany, Boston, Burlington, Chicago (still recovering from a historic snow drought), Cleveland, Concord, Detroit, Montreal, Ottawa, Portland (ME), Toronto, and Worcester probably have the highest risk of seeing some accumulations of snow in April. Other cities to the south, including Allentown, Harrisburg, New York City, and Philadelphia have some possibility, as well. Furthermore, the objective analogs, teleconnection analogs behind my April thoughts, and some recent runs of the GFS hint that New York City might see its first April freeze since 2007. The last time the temperature dropped to 32° in NYC in April was April 9, 2007 when the mercury fell to 32°. During that cold spell, the temperature fell to or below freezing on April 6-9, with the lowest reading being 30° on April 8. Such an outcome is not assured, but the odds are probably around 1-in-3.

 

More immediately, the guidance continues to indicate that a moderate to significant snowstorm will affect the Plains States this weekend. That's the system that will eventually spawn secondary development along the East Coast likely providing some portion of the Middle Atlantic region and possibly southern New England with at least some accumulating snow.

 

Kansas City, which picked up 0.2" snow yesterday bringing its seasonal total to 25.4" (36th highest), appears to be in line for a 3"-6"/4"-8"-type snowfall late Saturday through much of Sunday. Some locally higher amounts might be possible. A seasonal figure at or above 30" still looks very realistic. A 4" snowfall would rank 2012-13 as the 20th biggest season.

 

St. Louis, which has somewhat below normal snowfall to date at 15.1" appears to be in line for a 3"-6" accumulation. That would bring the city above normal for the winter.

 

In terms of the March ideas, so far things are working out in many areas in terms of snowfall. The Middle Atlantic region and southern Ontario are notable exceptions so far and those exceptions vividly illustrate the limits to trying to forecast in the extended range.

 

From Message #631 (2/19):

 

FWIW, the current mix of analog cases suggests the potential for a snowy March in parts of the Mid-Atlantic region and New England. The Ohio Valley, southern Ontario and southern Quebec would likely seek their most snowfall in March since 2011. 

March snowfall for select cities based on the analog cases (weighted for frequency of cases): 

 

Boston: 9.7" (snowiest since 2009)

Cleveland: 10.8" (snowiest since 2011)

Montreal: 26.0 cm/10.2" (snowiest since 2011)

New York City: 7.2"  (snowiest since 2009)

Toronto: 21.7 cm/8.5" (snowiest since 2011)

Washington, DC: 6.8" (snowiest since 1999); excluding 1960: 2.2" (snowiest since 2009)

 

Monthly snowfall for those cities through March 21 is as follows:

 

Boston: 20.6"

Cleveland: 6.6"

Montreal: 50.0 cm (19.7")

New York City: 7.3"

Toronto: 8.2 cm (3.2")

Washington, DC: 0.2"

 

From #700 (3/15):

 

My opinion of prospects for at least some accumulation of snow for the 3/15-3/25 timeframe for select cities is as follows:

 

Boston: Very Likely

Burlington: Very Likely (at least one accumulation of 4” or 10 cm or more is possible)

Chicago: Likely

Cleveland: Likely

Harrisburg: Likely

Hartford: Very Likely

Kansas City: Possible

Montreal: Very Likely (at least one accumulation of 4” or 10 cm or more is possible)

New York City: Possible

Ottawa: Very Likely

Philadelphia: Possible

Toronto: Likely

Washington, DC: Possible

Worcester: Very likely (at least one accumulation of 4” or 10 cm or more is possible)

 

Outcomes to Date (3/15-21):

 

Boston: 7.5"

Burlington: 10.2" (9.6" on 3/19-20)

Chicago: 0.1"

Cleveland: 3.5"

Harrisburg: 2.3"

Hartford: 5.3"

Kansas City: 0.2"

Montreal: 35.6 cm/14.0" (34.3 cm/13.5" on 3/19-20)

New York City: 3.0"

Ottawa: 26.3 cm/10.4"

Philadelphia: Trace

Toronto: 5.0 cm/2.0"

Washington, DC: Trace

Worcester: 7.9" (7.9" on 3/18-19)

 

The single biggest takeaway is that analogs coupled with the dynamical guidance can provide insight, but there are limitations. Obviously, I'm unhappy about the disparity between my thoughts and outcomes to date in some areas. Philadelphia, Toronto, and Washington, DC have not done as well as I had expected so far. There's still time and much will likely depend on the 3/24-26 event for Philadelphia and Washington's monthly snowfall or lack thereof.

[GaWx]

Folks,
Well, an amazing thing happened at 6:40 AM this morning: Savannah, GA, on the 3rd day of spring, received light sleet that was mixing in with light rain according to reports I just read! At the Hunter military base in Savannah, it was 44/22 at 6 AM, just before it started. Together with the great Waycross snow flurry earlier this month, this makes an incredible two March wintry precip. events in SE GA this month!

I'm aware of only three official spring wintry precip. events in Savannah, all being IP:

 

- The March 28 of 1955 trace of IP. Like for this one, the AO had a strong negative peak a little before that date: -3.758 on 3/21. (Also, they got their first measurable snow in 14 years on 2/12/2010, which was 6 days after the very low -5.205 AO of 2/6/10. Very freaky and special things sometimes happen in the SE US very far south near or just after extremely -AO events. This time, one happened in my hometown two days after a record low AO for late March!)

 

- The March 23 of 1968 trace of IP. This was actually during a +AO.

 

- The March 24 of 1983 trace of IP. This was during a moderate -AO and was produced by the same storm that produced the big snow further inland in a decent portion of the SE US.

[donsutherland1]

Folks,

Well, an amazing thing happened at 6:40 AM this morning: Savannah, GA, on the 3rd day of spring, received light sleet that was mixing in with light rain according to reports I just read! At the Hunter military base in Savannah, it was 44/22 at 6 AM, just before it started. Together with the great Waycross snow flurry earlier this month, this makes an incredible two March wintry precip. events in SE GA this month!

I'm aware of only one official spring wintry precip. event in Savannah: the March 28 of 1955 trace of IP. Like for this one, the AO had a strong negative peak a little before that date: -3.758 on 3/21. Also, they got their first measurable snow in 14 years on 2/12/2010, which was 6 days after the very low -5.205 AO of 2/6/10. Very freaky and special things sometimes happen in the SE US very far south near or just after extremely -AO events. This time, one happened in my hometown two days after a record low AO for late March!

Thanks for sharing this information. Do you have any information on the last time there were two frozen precipitation events in southeast Georgia in March. I'm sure it's probably a long time ago, if such records are available.

[DaculaWeather]

Thanks for sharing this information. Do you have any information on the last time there were two frozen precipitation events in southeast Georgia in March. I'm sure it's probably a long time ago, if such records are available.

LOL! Don... if they are available, Larry has them!   

[GaWx]

Thanks for sharing this information. Do you have any information on the last time there were two frozen precipitation events in southeast Georgia in March. I'm sure it's probably a long time ago, if such records are available.

 

Don,

1) You're welcome. I'm not aware of the last time that there were two different frozen precip. events in March in SE GA. Honestly, I don't have that specific info and have a lot of doubt that specific info exists. I did just check my Savannah records fwiw, which go back to March of 1949. There have not been two different frozen precip. events at Savannah in March going back at least to 1949. Of course, that's not to say that there wasn't a second one somewhere else in SE GA during any particular March. Keep in mind that the two events of march 2013 were in two different cities: Waycross had flurries earlier in the month and then Savannah had today's IP.

 

2) I had to modify my earlier post about past spring Savannah wintry precip. events. I had said that I was aware of only the one from 1955. I have since added the 3/23/1968 and 3/24/1983 trace IP events to the post.

[donsutherland1]

Don,

1) You're welcome. I'm not aware of the last time that there were two different frozen precip. events in March in SE GA. Honestly, I don't have that specific info and have a lot of doubt that specific info exists. I did just check my Savannah records fwiw, which go back to March of 1949. There have not been two different frozen precip. events at Savannah in March going back at least to 1949. Of course, that's not to say that there wasn't a second one somewhere else in SE GA during any particular March. Keep in mind that the two events of march 2013 were in two different cities: Waycross had flurries earlier in the month and then Savannah had today's IP.

 

2) I had to modify my earlier post about past spring Savannah wintry precip. events. I had said that I was aware of only the one from 1955. I have since added the 3/23/1968 and 3/24/1983 trace IP events to the post.

Thanks Larry. You're probably right that such information likely does not exist. Even as the events occurred in different locations in SE GA, it's still very impressive that SE GA had two such events this month.

[donsutherland1]

Some early morning thoughts...

 

1. The storm affecting the Plains States is behaving quite well so far. Already, Kansas City has reached 4.5" snow bringing its seasonal total to 30.3". That is the 18th highest figure on record and just below 30.4" for winter 1958-59.

 

2. The storm will very likely track into the Ohio Valley with secondary development occurring along the East Coast in response to the severe blocking. Given the confluence and blocking, the storm is unlikely to track as far to the north as some of the NAM runs had been suggesting. That means that snowfall amounts north of central New Jersey will likely fall off. NYC should still receive a light accumulation, making 2013 the first time there have been 3 accumulations after March 15 since 1965. Philadelphia probably has the best chance to receive a moderate accumulation of snow out of the major East Coast cities. There, the idea of a 2"-4"/3"-6" type accumulation continues to look good. Parts of western Virginia and western Maryland into interior portions of southern and central Pennsylvania have the highest chance of receiving 6" or more of wet snow.

 

3. The generally colder than normal pattern is likely to persist into April. There continue to be some hints of an outbreak of unseasonably cold air that could allow for some snow in such cities as Chicago, Cleveland, Albany, Worcester, and Boston, along with the chance that NYC could see its first April freeze since 2007.

[uncle W]

Some early morning thoughts...

 

1. The storm affecting the Plains States is behaving quite well so far. Already, Kansas City has reached 4.5" snow bringing its seasonal total to 30.3". That is the 18th highest figure on record and just below 30.4" for winter 1958-59.

 

2. The storm will very likely track into the Ohio Valley with secondary development occurring along the East Coast in response to the severe blocking. Given the confluence and blocking, the storm is unlikely to track as far to the north as some of the NAM runs had been suggesting. That means that snowfall amounts north of central New Jersey will likely fall off. NYC should still receive a light accumulation, making 2013 the first time there have been 3 accumulations after March 15 since 1965. Philadelphia probably has the best chance to receive a moderate accumulation of snow out of the major East Coast cities. There, the idea of a 2"-4"/3"-6" type accumulation continues to look good. Parts of western Virginia and western Maryland into interior portions of southern and central Pennsylvania have the highest chance of receiving 6" or more of wet snow.

 

3. The generally colder than normal pattern is likely to persist into April. There continue to be some hints of an outbreak of unseasonably cold air that could allow for some snow in such cities as Chicago, Cleveland, Albany, Worcester, and Boston, along with the chance that NYC could see its first April freeze since 2007.

today the NAO was at its lowest point of the season...the AO is still below -4...This April could make up for the warm ones we have been getting lately...

[donsutherland1]

today the NAO was at its lowest point of the season...the AO is still below -4...This April could make up for the warm ones we have been getting lately...

IMO, a lot will depend on just how cold the first half of the month turns out. It could turn milder afterward, but that's not cast in stone. It would be nice to see a little snow, too.

[donsutherland1]

Brief evening update:

 

1. Kansas City picked up a storm total of 5.4" snow bringing the seasonal figure to 31.2". That ranks 15th highest.

2. St. Louis has received 8.7" of snow so far. That brings the March figure to 10.2". That's the highest March snowfall there since March 1989 when 11.0" fell. It is possible that additional snowfall will bring the March 2013 figure above 11.0" to the highest figure for March since 1978 when 15.4" accumulated.

[Chicago WX]

St. Louis has received 11.7" of snow with this storm, as of 6:55pm. 12.1" is their largest March snowstorm on record, back on March 24, 1912.

 

0655 PM SNOW 1 SSW HAZELWOOD 38.76N 90.37W
03/24/2013 M11.7 INCH ST. LOUIS MO ASOS

[donsutherland1]

From the NWS:

 

000
SXUS73 KLSX 250224
RERSTL

RECORD EVENT REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
920 PM CST SUN MAR 24 2013

...RECORD DAILY MAXIMUM SNOWFALL SET AT ST LOUIS LAMBERT
INTERNATIONAL...

A RECORD SNOWFALL OF 12.2 INCHES WAS SET AT ST LOUIS LAMBERT
INTERNATIONAL AIRPORT TODAY. THIS BREAKS THE OLD RECORD OF 12.1
INCHES IN 1912.


A STORM TOTAL AND FINAL TALLY WILL BE SENT AT MIDNIGHT.

$$

 

[donsutherland1]

Final total for 3/24 in St. Louis: 12.4" (biggest March snowstorm on record).

[Chicago WX]

17.0" officially at Springfield IL (SPI) yesterday. That's the greatest 24 hour amount in their recorded history (since 1884).

 

17.0" on March 24, 2013

15.0" on February 28, 1900

13.3" on January 1-2, 1999

12.6" on January 30-31, 1914

11.3" on January 31-February 1, 2008

 

 

SNOWFALL (IN)YESTERDAY       17.0 R         MONTH TO DATE   18.1                       SINCE MAR 1     18.1                       SINCE JUL 1     31.6

[DaculaWeather]

Latest Winter Storm Summary: http://www.daculaweather.com/4_hpc_winter_storm_summary.php

[donsutherland1]

Morning thoughts...

 

1. The remarkable blocking pattern was a productive one, in general, though some areas did miss out. Accumulating snow was reported in such cities as Baltimore, Boston, Cleveland, Harrisburg, New York, Newark, Philadelphia, Richmond, and Washington, among others.

 

2. Missouri and Illinois experienced a major spring snowstorm. In parts of Missouri and Illinois, the snowfall was historic for this late in the season. St. Louis picked up 12.8" on 3/24-25, the biggest March snowfall on record there. Springfield, IL picked up 18.5" on 3/24-25, the biggest snowstorm on record in that city.

 

Looking ahead, it appears that the blocking responsible for the winter weather will fade, but might experience a brief resurgence in early April. The combination of the seasonal migration of the jet stream, longer-term demise of the blocking, and shortening of the wave lengths all suggest that after perhaps a cold start to April, the potential for a rapid transition into a warmer pattern could be on the table.

 

Before then, the potential still exists for an early April cold shot, perhaps resulting in the first April freeze in NYC since 2007 and possibly some additional accumulating snow across Upstate New York, southern Ontario, southern Quebec, and parts of New England.

 

As the possible transition from a winter to spring pattern takes place, there will be the potential for some increase in severe weather in what has been a quiet season so far.

[andyhb]

The 12z AO forecasts agree with you, with a secondary drop in the ~April 3rd timeframe. This, along with several other factors should act to suppress the closed low moving inland in the SW this weekend, if not shear it apart upon interaction with the northern stream dropping out of the Hudson's Bay region.