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Tulip Trouncer Threat - End of March/ Early April


Baroclinic Zone

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Sup gang?!

Thought I get the ball rolling for the threat centered around the 30-31st.

Just taking a look at the latest overnight models and the threat looks plausible.

Nice closed s/w traveling across the US through AZ/NM looks to phase with a northern stream s/w diving out of Manitoba forming a sizable coastal storm around the VA coast traveling NE. Nice spike in the PNA/NAO suggest this as well. With the NAO progged to move towards the positive we should be worried about a warmer solution bu that's a detail to be determined as the threat comes closer.

Stayed tuned.

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Check this out: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.nao_index_ensm.html

That is time sensitive to about 4 days given to intra-weekly variability with the NAO. Having said that ... it is verify nicely as of last night... 2 days worth of modality has seen the scalar value drop more the 1SD already. Moreover, this has been flagged for days.

Next weeks event is scheduled near the bottom of this new -NAO nadir. Meanwhile, there is a hefty PNA spike to nearly +2SD - and we may not yet be seeing the full extent of western ridge amplitude associated with that in the deterministic solutions.

Here is the PNA from both CPC and CDC (...again, time sensitivity to variable lengths)

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.pna_index_ensm.html

http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.pn.png

It is noted the the NAO is rising more discerned at CDC than CPC during the time frames in question; it is not uncommon for these two source to diverge timing-wise. They calculate their respective values differently, so this is understandable. The CPC specifically uses geoptential depth anomalies, whereas the CDC uses specifically low-level wind flux. It is also important to note that these are based on the GFS ensemble cluster - and there is really 21 members (not just 12) for both agencies. It would be interesting to see the ECMWF's ensemble derivitives because the 2 cycle trend from 12z to 00z was right up Kevin's pa-tooty.

The sum total of the GFS teleconnectors argument is toward more amplitude. Independently these two want to drill heights down from the OV/MA and NE regions; together they produce a convergent signal for such a negative anomally in the vicinity.

The purpose of using the teleconnectors is to paint the probability canvas - so to speak. I started a thread a while ago called "Don't give up hope on an encore", or something like that - to which I sardonically changed the title to "give up hope"... Anyway, the start for that thread really was a reconnoiter to where we sit now looking on toward next week. The probability for greater amplitude is still there ... and in fact, has gained additional favor. Deterministic runs should be on the lover's side going forward.

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Euro ensembles also have the HA signal with a weakening west based -NAO and a 50/50 low. It's not big on the +PNA ridge but it does have a + tilted ridge spilling into the Rockies, and a sw US trough. It's a signal on all three major ensembles, with the Canadian ensembles the warmest.

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Sup gang?!

Thought I get the ball rolling for the threat centered around the 30-31st.

Just taking a look at the latest overnight models and the threat looks plausible.

Nice closed s/w traveling across the US through AZ/NM looks to phase with a northern stream s/w diving out of Manitoba forming a sizable coastal storm around the VA coast traveling NE. Nice spike in the PNA/NAO suggest this as well. With the NAO progged to move towards the positive we should be worried about a warmer solution bu that's a detail to be determined as the threat comes closer.

Stayed tuned.

During the winter, but not necessarily at this time of year; it's all about the track and depth of the closed low.

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During the winter, but not necessarily at this time of year; it's all about the track and depth of the closed low.

Normally I'd agree, but this system looks like a more traditional phase job than a closed off bowling ball rolling across the county and scooting out S of us. This looks to have some northern stream interaction and depending upon how much phasing and strength of the NAO will have a say in the overall track imo.

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Normally I'd agree, but this system looks like a more traditional phase job than a closed off bowling ball rolling across the county and scooting out S of us. This looks to have some northern stream interaction and depending upon how much phasing and strength of the NAO will have a say in the overall track imo.

What I said is still applicable because there exists more of a disconnect amongst large scale teleconnectors, regardless....the NAO domain is less relevant because the atmosphere's envelope of influence on individual SWs is smaller @ this time of year.

Is there still a correlation with respect to the NAO, I guess, but it's fairly trivial after about March 15.

That being said, it is possible that we are more dependant upon the intricacies of a phase job, than usual @ this time of year....haven't examined it.

This is why cut offs are much more prevalent this time of year......with shorter wavelengths, there is more margin for error as opposed to January, when a lack of ridging over an eskimo's hut in Nanavut can keep things progressive.

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Doesn't seem NCEP is too keen on these models today...

DAY 7 WED AND DAY 8 THURSDAY BECOMES MORE UNCERTAIN IN TIMING WITH ABOVE MENTIONED DIFFERENCES. REGARDLESS IT SHOULD BE A STRONG SYSTEM WITH VARIETY OF WEATHER IMPACTS BOTH SPRING AND WINTER LIKE OVER THE ERN THIRD OF CONUS.

ROTH/ROSENSTEIN

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BOX thinking Sping is Engaging soon

00Z MODEL GUIDANCE SUGGEST THE HIGH LATITUDE BLOCKING PATTERN MAY

RELAX MID TO LATE NEXT WEEK WITH POLAR VORTEX OVER SOUTHEAST CANADA

WEAKENING AND EXITING INTO THE NORTH ATLANTIC. APPEARS THIS WILL BE

REPLACED BY SPLIT FLOW ACROSS THE CONUS WITH AN ENERGETIC SOUTHERN

STREAM. THIS WOULD FAVOR TEMPERATURES MODERATING TO SEASONABLE

LEVELS /~50F/ MID TO LATE NEXT WEEK ALONG WITH POTENTIAL WET

SOUTHERN STREAM SYSTEM MARCHING ACROSS THE GULF STATES.

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That's still in the general time frame so it's a plausible solution.

I think this system will be the pattern changer into Spring.

Stil about 6 days out, so I still think this threat has legs. I think we could see it stay suppressed in the models for another 36 hours, and then start to see a trend back toward a stronger s/w tracking into the central Plains along with stronger downstream ridging.

I agree to some extent that this storm looks like a sort of pattern changer into Spring. We'll have to wait for hints of ridging out west to break down before real warmth can invade the east. But following this storm, the next ones in line will have a better shot at cutting to our west.

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A month ago people would have been slitting there wrist over the roller coaster ride on the models for this next potential, I know i could go either way with it as not much use for snow this time of year here but it would extend activities further north......

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