brooklynwx99

So, there has been a lot of speculation as to why the pattern for the beginning of March has taken such a turn since just last week. I was pretty much in agreement with much of the meteorological community that the beginning of March would be quite warm as the pattern would be breaking down. It appeared that the tropical forcing would move into unfavorable areas of the Pacific for E US winter weather, like towards the Maritime Continent. However, that tropical forcing has become less and less of a factor in the pattern, as the amplitude of the wave looks quite low: So, instead, there must be another pattern driver that's led to such a dramatic change in the NH waveguide. It looks like the culprit is an extratropical cyclone over the W Pacific near Japan. It will develop by the beginning of next week, and it looks to become a highly anomalous cyclone, reaching over 4 sigma below normal SLP: This cyclone will induce an extension of the Pacific jet and anticyclonic wave breaking, which leads to the anomalous ridging over the EPO domain: I don't think that this is a head fake, and there is the potential for a significant high-latitude blocking event. It hinges on the strength of the cyclone in the Pacific, but there is tremendous agreement between models and their ensembles, so I do think that it's a legitimate pattern driver. Something similar to this also happened with Nuri at the end of October 2014, which was also a highly anomalous N Pacific cyclone. Nuri had a tremendous impact on the pattern in November 2014 with regards to N Pacific blocking: Therefore, I do believe that the first couple (or perhaps few?) weeks of March hold elevated potential for a significant late-winter event. Time will tell, but things should start to ramp up once heading into the start of the month.

So, there has been a lot of speculation as to why the pattern for the beginning of March has taken such a turn since just last week. I was pretty much in agreement with much of the meteorological community that the start of March would be quite warm as the pattern would be breaking down. It appeared that the tropical forcing would move into unfavorable areas of the Pacific for E US winter weather, like towards the Maritime Continent. However, that tropical forcing has become less and less of a factor in the pattern, as the amplitude of the wave looks quite low: So, instead, there must be another pattern driver that's led to such a dramatic change in the NH waveguide. It looks like the culprit is an extratropical cyclone over the W Pacific near Japan. It will develop by the beginning of next week, and it looks to become a highly anomalous cyclone, reaching over 4 sigma below normal SLP: This cyclone will induce an extension of the Pacific jet and anticyclonic wave breaking, which leads to the anomalous ridging over the EPO domain: I don't think that this is a head fake, and there is the potential for a significant high-latitude blocking event. It hinges on the strength of the cyclone in the Pacific, but there is tremendous agreement between models and their ensembles, so I do think that it's a legitimate pattern driver. Something similar to this also happened with Nuri at the end of October 2014, which was also a highly anomalous N Pacific cyclone. Nuri had a tremendous impact on the pattern in November 2014 with regards to N Pacific blocking: Therefore, I do believe that the first couple (or perhaps few?) weeks of March hold elevated potential for a significant late-winter event. Time will tell, but things should start to ramp up once heading into the start of the month.

yeah, the NAO is so positive that the TPV kinda acts as a pseudo-50/50 and helps provide confluent flow in SE Canada. it's weird, but that same kind of pattern was able to produce Marches 2014/15, which were snowy for the entire E US. lots of cold overrunning snows in those months

this is some serious split flow with an active STJ, which ups the risk for phasing scenarios as well. it's a great pattern as advertised

this is a really nice look. cold and active as the -EPO forces the boundary S split flow evident too with the STJ in the picture

this pattern would provide lots of chances for us heading into March development of a stout -EPO lets cold air bleed S... would probably be overrunning primarily but coastals could be more favored as the pattern matures. good stuff

yeah, this pattern is a nice look for the E US N of DC development of a stout -EPO lets cold air bleed S... would probably be overrunning primarily but coastals could be more favored as the pattern matures. good stuff

GEFS is juicy in the LR… this is a big time overrunning setup as modeled with split flow

this is gorgeous. big March 2015 vibes with a cold overrunning pattern -EPO with split flow

gorgeous

yeah, it's March '15-esque. would be an active overrunning look if it were to verify

the pattern showing up in the LR is actually a bit deceiving... this does look like a "torch" at first glance, but there's actually a ton of cold air in SE Canada, and the TPV S of Greenland provides confluence. so, even though there's a SE ridge, there would more than likely be a pretty stout cold press with lots of HP over the top March 2015 is a pretty similar analog to this type of gradient pattern. NOT saying that we're getting a month this anomalous, but the NAO was extremely positive and there was considerable SE ridging. however, we all remember how the TPV parked S of Greenland provided significant confluence and kept areas N of DC colder than average thanks to the Pacific help. so, just because you see a SE ridge and +NAO doesn't mean you torch if the TPV is in a favorable location for providing confluence so, if this pattern was to verify (I have no reason to believe it's outlandish), then we would see an active overrunning pattern with lots of chances to open the month. let's hope the guidance holds on this March '15-esque look

GEFS does just that... this is March 2015-esque NOT saying that this March will be anything that extreme, but the advertised pattern could certainly deliver with overrunning events riding the boundary

this is a significant amplification trend on the NAM... the entire trough has been tilting more favorably for an entire model cycle. something to watch for coastal peeps as that's really close to an interesting outcome

this is a significant amplification trend on the NAM... the entire trough has been tilting more favorably for an entire model cycle. something to watch for coastal peeps as that's really close to an interesting outcome

would be some surprises in store if the 250mb jet verifies that strong... models often underdo the blossoming of precip with UL forcing

a jet streak like that would mean business... could be some surprises in store if one of that strength verifies. would like to see this from other hi-res guidance

I mean... the NAM and HRRR make meteorological sense in their depictions of the precip shield the NAM only beefed up because of a more potent 250mb jet, which checks out. models often underdo blossoming precip in those scenarios, so we'll have to see if other mesos catch on to the stronger jet streak

there is a slight risk for the trailing wave on PD weekend to get its act together... definitely not impossible and there would be SS origin if it were to occur. worth keeping an eye on since there really isn't much else to look at

GFS looks better… way different with the NS, should be in a good way S vort is definitely more consolidated

EPS follows suit. more consolidated trough, similar to the OP

certainly better at 500. NS is digging more and the trough is a bit held back

ECMWF looks better. NS is digging more and the trough is more held back

agree. digging farther W and the trough is more held back

GFS is much improved aloft