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Feb 24th threat. Signal has been there for a while now


Typhoon Tip

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So typical for the GFS to do this ... it just has a propensity to drop southern stream impulses in middle ranges - it's like it has a gene for it, just so much as one can have blue eyes, this is it's brown eye.   

 

In this run, there is a slight more northern stream dynamics dumped into the impulse near 84 hours out of the Dakotas, but the southern stream is weakened to the point where it's ineffectual by 100 or so hours.   My hunch is the other model types won't be so stingy with that.  

gfs is still pretty close to a decent event anyway. 

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As we head into blocky regime ... expect the GFS to perform less adequately. It's native speed bias is in conflict with blocking, such that it either shreds reality, or produces delusions with higher frequency resulting in poorer overall performance.  

 

 

This is why it performed seemingly so well in the several weeks prior to the blizzard - the flow was actually verifying faster than normal, much of the time, which gave the GFS an advantage.  

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Heh, the NAM's last 3 cycles have had .49, .68, and .36 at BOS on the FRH grid.  Synoptically, there is a big fist of DPVA ripping up over the top of a fairly steep baroclinic axis as that quasi closed low in the N GL's carves east over night.   

 

Not sure which QPF will verify ... Course of least regret may just be to take the average, because the evolution in the charting shows that the difference between that .33" and .68" isn't really systemic, but is entirely based on nuanced differences in where the model locates the action.  The .68 happens to be over eastern zones and the coastal plain; the latter .33 is because the max region is about 1.23 miles off the coast.  

 

BL is "springy" today, but it is going to stay cold just off the deck.  When that DPVA rips overhead there is likely to be a UVM spike, regardless, and the column should burst snow for a while tonight.   If the .68 were closer to reality, you may be be talking 3 or 4" for a few folks.  

 

I just looked at the GFS and synoptically it's evolution isn't appreciably different - slightly less QPF, but that could simply be a matter of not having the same dynamical resolution.  The 00z GGEM also smokes a .25 to .4" liq equiv from CT through SE NH during a dynamical thickness collapse...   

 

You know, I think there is enough evidence for a 2-4" snow fall that we may be glossing over an interesting, albeit low impactor, in lieu of bigger ticket potentials in the middle range, and beyond.  The con is mainly the warmish boundary layer, but we have to remember that from mid Feb to the end of March, warm days in an improved solar insolation can be eradicated with extreme rapidity...   hm

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Is there any meteorological mechanism that can bring this thing north a little bit?  I'm in the Southern NH / Norther Merrimack Valley snow hole and hoping for some relief.


Also, I'd like to at least see the smaller mountains around Southern NH get involved in this one.

 

Please give me a mechanism, phenomena, or excape route to root for!

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Juicy and cold?

 

 

Not too cold from what I'm seeing. Could be a little wet for us.

 

 

Show; don't tell.

 

Marginal for South Coast areas but it looks cold enough once you move inland.  Verbatim, it also looks like SW areas may have issues until the mid-levels develop as the storm exits the coast.  E MA, CC look like they are ~1.00"

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Let's just say the 12z GFS Ensm are juicy.

Haven't seen the individuals but I would bet the wet ones are warm and the cold ones are dry, resulting in a mean SLP position and QPF distribution that looks deceptively like a snowstorm.

 

But of course at this range it doesn't really matter what the specifics show.  I'm just glad the GFS and ens are showing a moderately strong coastal storm, basically in line with other guidance.

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...WET AND ACTIVE WEATHER PATTERN TO CONTINUE ACROSS THE US...

OVERVIEW...

MANUAL SURFACE GRAPHICS CONTINUE WITH THE PROGRESSION OF SYSTEMS

ACROSS THE MIDWEST AND EAST COAST. THE 19/00Z ENSEMBLE GUIDANCE

WAS BEST REPRESENTED BY THE ECMWF THROUGH DAY 5...WHICH REMAINS ON

THE SLIGHTLY SLOWER SIDE OF THE SPREAD VS THE CANADIAN/GEFS AND

NAEFS. SPREAD ENLARGES ACROSS THE EAST PACIFIC AND DOWNWIND INTO

THE CENTRAL PLAINS/GREAT LAKES FOR DAYS 6-7...AND MUCH OF IT...IS

TIED TO TIMING INDIVIDUAL SHORTWAVE STRENGTH EJECTING OUT OF THE

CENTRAL ROCKIES.

SYSTEM RELEVANCE...

THE DAY 3 SYSTEM TRACKING ACROSS THE CENTRAL STATES REMAINED ON

TRACK WITH LITTLE VARIATION FROM CONTINUITY.

DOWNSTREAM...CONDITIONS REMAINED FAVORABLE FOR SECONDARY

CYCLOGENESIS ALONG THE CAROLINA COAST/PIEDMONT REGION AND BROAD

ISENTROPIC LIFT/ UPGLIDE OF GULF MOISTURE INTO THE MID- TO

UPPER-LEVEL CIRCULATION POSITIONED INVOF THE GREAT LAKES.

THE DAY 4-5 SYSTEM EMERGING OFF THE CAROLINA COAST REMAINS IN A

FAVORABLE POSITION FOR INTENSIFICATION BETWEEN SATURDAY NIGHT AND

SUNDAY MORNING AS IT TRACK NORTHEASTWARD ALONG THE EASTERN

SEABOARD. TO FULLY RESPECT THE 19/00Z GEFS/GFS SOLUTION WOULD BE

TO SWIFTLY EJECT THE SYSTEM AWAY FROM THE NORTHEAST. AT THIS

POINT...THE UPSTREAM PATTERN IS DRIVING THIS SOLUTION AND RECENT

TRENDS IN THE GFS/ECMWF AND CANADIAN SUGGEST THERE WILL BE A

SLOWER PROGRESSION OF THE PATTERN THAN WHAT THE 19/00Z GFS

PACKAGES SUGGEST.

THE DAY 4-5 SYSTEM INTENSIFYING OUT WEST IN THE GREAT

BASIN...APPEARS TO EJECT SEVERAL SHORTWAVES NORTHEASTWARD INTO THE

CENTRAL PLAINS...AND THE DETERMINISTIC THICKNESS/TEMPERATURE

FIELDS DO NOT SUPPORT A `LONE` OR SINGLE (VERTICALLY-STACKED)

CYCLONE. RATHER A COMPLEX `TROWAL`...AND TRIPLE POINT LOW

STRUCTURE. ONE THAT EJECTS AND INTENSIFIES AN ADDITIONAL SHORTWAVE

AND SURFACE WAVE ACROSS THE SOUTHEAST AND INTO THE CAROLINAS

BETWEEN DAYS 6-7. THE `TROWAL` STRUCTURE IS DEPICTED ON THE

SURFACE GRAPHICS AS A COMPLEX OCCLUSION...WITH THE PRIMARY WAVE

EMERGING ACROSS THE PIEDMONT REPRESENTING SOMETHING THAT PATTERNS

ITSELF MORE LIKE A NEGATIVELY-TILTED TROUGH.

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Haven't seen the individuals but I would bet the wet ones are warm and the cold ones are dry, resulting in a mean SLP position and QPF distribution that looks deceptively like a snowstorm.

 

But of course at this range it doesn't really matter what the specifics show.  I'm just glad the GFS and ens are showing a moderately strong coastal storm, basically in line with other guidance.

nope.

 

the gfs and its ensembles are just taking the energy through the lakes further N and E than the euro owing to much less ridging extending up into James Bay...consequently the primary is further north and east, the secondary forms later is is generally weaker and there's greater mid-level warming out ahead of them. and the gfs tends to run mild anyway. 

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