Jump to content
  • Member Statistics

    17,607
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

3/17-3/18 Storm Threat Discussion


Zelocita Weather

Recommended Posts

  • Replies 2.2k
  • Created
  • Last Reply

HPC Discussion from earlier this morning:

 

...MIDDLE MS-OH VALLEYS/CENTRAL APPALACHIANS/MID-ATLANTIC...

A NARROW BUT POTENTIALLY SIGNIFICANT SWATH OF SNOW POSSIBLY MIXED
WITH SLEET AND ICE IS EXPECTED TO DEVELOP FROM SOUTHERN MISSOURI
INTO THE OHIO VALLEY ON SUNDAY BEFORE EXPANDING INTO THE CENTRAL
APPALACHIANS AND MID-ATLANTIC REGION SUNDAY NIGHT AND EARLY
MONDAY.  THE NAM WAS RULED OUT DUE TO ITS FAST SOLUTION RELATIVE
TO THE SOLUTION ENVELOPE WHILE ASPECTS OF THE GFS WERE ALSO RULED
OUT PARTICULARLY THE PRECIPITATION ASSOCIATED WITH THE LEAD
SURFACE LOW APPROACHING THE APPALACHIANS THAT APPEARS TO BE
AUGMENTED THROUGH CONVECTIVE GRID-SCALE FEEDBACK.  OTHERWISE ITS
SOLUTION APPEARS USEFUL BUT IS LESS THAN IDEAL.  PRESENTLY PREFER
THE LOW TRACKS AND THEIR RESPECTIVE LIQUID EQUIVALENTS AND P-TYPES
OF THE 12-00Z ECMWF/00Z UKMET/12Z ECMWF ENSEMBLE MEAN THE
MOST...WITH THE 00Z GFS/00Z CANADIAN OFFERING SOME BENEFIT AS
WELL.  THE SNOW PROBABILITIES ACROSS MISSOURI INTO THE SOUTHERN
OHIO VALLEY ARE ASSOCIATED WITH MORE MARGINAL TEMPERATURES
PROFILES INITIALLY AND WILL BE COMPETING WITH DRIER AIR ENTRAINING
IN FROM THE NORTH AND UNCERTAINTIES WITH IF AND EXACTLY HOW
CONVECTION WILL AFFECT MOISTURE RETURN.  THUS...PROBABILITIES OF 4
INCHES OR MORE ARE ON THE LOW SIDE OF THE SPECTRUM DUE TO MULTIPLE
UNCERTAINTIES.  HOWEVER...IF ONE USES SOME OF THE DIRECT MODEL
OUTPUT FROM THE GFS/ECMWF...4 TO EVEN 8 INCHES OF SNOW COULD FALL
ACROSS SOUTHERN MISSOURI...BUT THESE AMOUNTS SEEM TO HAVE A LOW
CHANCE OF OCCURRING.  FARTHER EAST...MODELS APPEAR TO BE COMING
INTO BETTER AGREEMENT WITH HIGHER SNOW TOTALS DEVELOPING ACROSS
THE CENTRAL APPALACHIANS...WHERE SOME AREAS COULD RECEIVE 6 TO 12
INCHES.  THUS...HAVE HIGH/MODERATE/LOW PROBABILITIES OF 4/8/12
INCHES RESPECTIVELY IN THIS AREA.  CONDITIONS FOR HEAVY SNOW EAST
OF THE APPALACHIANS ARE LESS CLEAR DUE TO THE UNCERTAIN ROLE OF
THE NORTHERN STREAM/INITIALLY WARM TEMPERATURES/GROWING SOLUTIONS
SPREAD. THUS...PREFERRED TO ADJUST DOWNWARD THE DIRECT MODEL
OUTPUT OF SOME OF THE MORE AGGRESSIVE SOLUTIONS THAT SUGGEST
TOTALS IN EXCESS OF 6 OR EVEN 8 INCHES NEAR WASHINGTON DC...UNTIL
SOME OF THE FACTORS CONTRIBUTING TO THE UNCERTAINTY ARE BETTER
RESOLVED.  AGAIN...PREFERRED A SOLUTION SOMEWHERE BETWEEN THE
ECMWF/UKMET/ECMWF ENSEMBLE MEAN...WITH SOME DOWNWARD ADJUSTMENTS
THEN MADE.  THE FINAL RESULT SHOWS THE HIGHEST SNOW PROBABILITIES
ACROSS THE CENTRAL APPALACHIANS...WITH MODERATE PROBABILITIES OF 4
INCHES AND LOW PROBABILITIES OF 8 INCHES OVER WASHINGTON DC.  A
NARROW ZONE OF SLIGHT PROBABILITIES OF 0.25 INCHES OF FREEZING
RAIN ALSO ACCOMPANY SOUTHERN FRINGES OF THE SNOW OVER PARTS OF THE
OHIO VALLEY.

JAMES

 

Link to comment
Share on other sites

Clearly two different camps developing with the SREF/CMC/NAM showing the more amplified and consolidated initial wave. We will have to see if the SREF back off a bit today. My gut says they will. But we still have to resolve how that initial wave is handled as the globals and CMC/shorter term models are up in arms in that regard. 

Link to comment
Share on other sites

Clearly two different camps developing with the SREF/CMC/NAM showing the more amplified and consolidated initial wave. We will have to see if the SREF back off a bit today. My gut says they will. But we still have to resolve how that initial wave is handled as the globals and CMC/shorter term models are up in arms in that regard. 

Is there any chance of the 2nd ,more significant SLP, to make it up the coast after the intial thump being forcast bhy th emore amplified models for Sun/Mon.?

Link to comment
Share on other sites

Clearly two different camps developing with the SREF/CMC/NAM showing the more amplified and consolidated initial wave. We will have to see if the SREF back off a bit today. My gut says they will. But we still have to resolve how that initial wave is handled as the globals and CMC/shorter term models are up in arms in that regard.

The GGEM has been pretty rock solid with its forecast so far and it did very well with the monday system last week leading the way on the strictly mid atlantic storm outcome. Educated guess is the GFS/EURO will step more towards a more consolidated LP and leave less energy behind compared to previous runs. The NAM is expected to be furthest north and wrapped of most if not all the models so that is no surprise to be honest john
Link to comment
Share on other sites

Some people are unnecessarily panicking over the sheered out models, trends were still great overnight and the SREF's delivered a top end MECS runs as well

I wouldn't start getting excited until tonight after 0z maybe, since the threat of too sheared out/PV suppression is still there. The 6z GFS started shearing out the energy again, and even if the PV is more conducive it will be hard to accumulate a lot of snow with 0.3-0.4" liquid over 12 hours. We need for it to come in heavy like the GGEM and NAM have. A sheared out solution like the Euro would likely be 1-3" tops.

Link to comment
Share on other sites

Is there any chance of the 2nd ,more significant SLP, to make it up the coast after the intial thump being forcast bhy th emore amplified models for Sun/Mon.?

IMO that comes up the coast it will literally put almost the entire are at above 95-95' snowfall levels. Think for that to happen we'd have to hope to delay the system crashing into the west coast and also that S/W coming through idaho to take it easy or my fear is it could deamplify the flow on the EC for second LP that would be the bigger part of the system

Link to comment
Share on other sites

I wouldn't start getting excited until tonight after 0z maybe, since the threat of too sheared out/PV suppression is still there. The 6z GFS started shearing out the energy again, and even if the PV is more conducive it will be hard to accumulate a lot of snow with 0.3-0.4" liquid over 12 hours. We need for it to come in heavy like the GGEM and NAM have. A sheared out solution like the Euro would likely be 1-3" tops.

Absolutely but IMO for this storm to be BIG we need that secondary LP to come up the coast as well. That thing comes up it will really bump up accumulations. Watching out west to see if those features dont deamplify the flow on the EC like we've seen this year with some of systems that couldve been big punted by what happened on the west coast
Link to comment
Share on other sites

 

 

 

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST NEW JERSEY...NEW

YORK CITY AND IMMEDIATE SUBURBS...AND LONG ISLAND.

.DAY ONE...TODAY AND TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

LOW PRESSURE PASSING TO THE SOUTH SUNDAY NIGHT INTO MONDAY EVENING

HAS SOME POTENTIAL TO PRODUCE A SIGNIFICANT SNOWFALL. IT IS STILL

TOO EARLY TO PREDICT THE EXACT LOW TRACK AND INTENSITY...OR THE

RESULTING INTENSITY AND DURATION OF SNOWFALL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

 
Link to comment
Share on other sites

Absolutely but IMO for this storm to be BIG we need that secondary LP to come up the coast as well. That thing comes up it will really bump up accumulations. Watching out west to see if those features dont deamplify the flow on the EC like we've seen this year with some of systems that couldve been big punted by what happened on the west coast

The kicker out west has to be watched-the more separation between them the better. You can see towards the end of the GFS run the kicker bearing down and forcing our storm to shear out and weaken as it goes east.

Link to comment
Share on other sites

The kicker out west has to be watched-the more separation between them the better. You can see towards the end of the GFS run the kicker bearing down and forcing our storm to shear out and weaken as it goes east.

And thats hurt many of our potentially big storms that couldve occured this year. Good part why we didnt see that BIG ONE because the kicker spacing was never too sufficient for prefectly timed phasing and negative tilt on the EC at the right time

Link to comment
Share on other sites

And thats hurt many of our potentially big storms that couldve occured this year. Good part why we didnt see that BIG ONE because the kicker spacing was never too sufficient for prefectly timed phasing and negative tilt on the EC at the right time

Seemingly EVERY time we r looking at a big dog huntin there is a kicker right behind that SLP. Thats why a pattern like this, with no  consistent blocking & too pogressive, will produce  moderate hits far more frequantly than major hits and obviously nothing historic thus far. It will be tough to bring about a SERF or Nam scenario obviously because you need the PV in a nearly perfect position ( moving more north but not so far that we torch with a strengthening SLP.

Link to comment
Share on other sites

And thats hurt many of our potentially big storms that couldve occured this year. Good part why we didnt see that BIG ONE because the kicker spacing was never too sufficient for prefectly timed phasing and negative tilt on the EC at the right time

Precisely point I just made :D

Link to comment
Share on other sites

Very rarely are you going to have an intense low in the TN Valley and not have precipitation issues on the immediate coast. It's just a fact of life. Out here we should get buried.

 

"cues all the people wishcasting for a weaker solution so they can have their imaginary 3-6""

The NAM at 6z has almost all sleet anywhere near the city, going later to freezing rain and mostly sleet well N and W. I don't think there is a very large window for a lot of snow especially near the city and coast. A stronger low introduces a wicked mid level warm layer-just look at what happened in NY/NH/VT just 2 days ago with how far north sleet made it. A weaker low makes for lighter precip that might have a hard time accumulating if it's daylight.

 

Hopefully your "out here we should get buried" comment was a stir the pot attempt.

Link to comment
Share on other sites

Clearly two different camps developing with the SREF/CMC/NAM showing the more amplified and consolidated initial wave. We will have to see if the SREF back off a bit today. My gut says they will. But we still have to resolve how that initial wave is handled as the globals and CMC/shorter term models are up in arms in that regard. 

Why do you feel that the sref's will back off today?

Link to comment
Share on other sites

The NAM at 6z has almost all sleet anywhere near the city, going later to freezing rain and mostly sleet well N and W. I don't think there is a very large window for a lot of snow especially near the city and coast. A stronger low introduces a wicked mid level warm layer-just look at what happened in NY/NH/VT just 2 days ago with how far north sleet made it. A weaker low makes for lighter precip that might have a hard time accumulating if it's daylight.

 

Hopefully your "out here we should get buried" comment was a stir the pot attempt.

I'd rather take my chances with a strong low, heavy front end snow and if I end as sleet that's fine by me.

Link to comment
Share on other sites

The 00z ECMWF Ens indies are really hit or miss. There really is no medium here at all. Either you eject all the energy and wind up with a big storm (monster in some cases), or you hold it back and a weak wave of snow spreads over the MA. 

 

I can't say I've ever seen energy being held back the way the OP GFS and the ECMWF have been holding it back though. 

Link to comment
Share on other sites

SREF are northwest still. Very wet.. 1+" QPF for everybody. A lot of members seem to be leaning northwest with the MSLP track and I would assume some are pretty warm.

But the mean looks like it would produce a really snowy scenario here.

http://mag.ncep.noaa.gov/data/sref/09/sref_namer_084_mslp.gif

There definitely has to be a bunch of rainers with a spread nw like that.

Link to comment
Share on other sites

SREF are northwest still. Very wet.. 1+" QPF for everybody. A lot of members seem to be leaning northwest with the MSLP track and I would assume some are pretty warm. 

 

But the mean looks like it would produce a really snowy scenario here. 

 

http://mag.ncep.noaa.gov/data/sref/09/sref_namer_084_mslp.gif

20 miles or so NW of the city the surface freezing line hangs tough while 850's go to 5C+. Sounds like ZR.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...