Jump to content
  • Member Statistics

    17,588
    Total Members
    7,904
    Most Online
    LopezElliana
    Newest Member
    LopezElliana
    Joined

February 4-5th Winter Storm Part 2


Chicago Storm

Recommended Posts

  • Replies 962
  • Created
  • Last Reply

I doubt it. the wave still has some to slow and that will take care of that. model performance at this range is looking pretty poor compared to what it "wants" to show.

 

True. But short of the southern stream wave trending stronger (still plausible with better sampling, though the window is closing), the flow's just too progressive.

 

gfs_namer_051_200_wnd_ht_s.gif

Link to comment
Share on other sites

LOT

 

TUESDAY-WEDNESDAY NIGHT...

CLOSED UPPER LOW ALONG THE CALIFORNIA COAST THIS (SUNDAY) AFTERNOON
IS PROGGED TO CURVE ACROSS THE DESERT SOUTHWEST THROUGH
MONDAY/MONDAY NIGHT...WITH A STRONG MID-LEVEL SHORT WAVE PROPAGATING
THROUGH THE BASE OF THE TROUGH AND BECOMING SOMEWHAT NEGATIVELY
TILTED WHILE EJECTING NORTHEASTWARD ACROSS THE SOUTHERN PLAINS ON
TUESDAY. MODEL AGREEMENT IS REASONABLE WITH THIS FEATURE AT THIS
DISTANCE...THOUGH AS WPC NOTES THE WRF-NAM/SREF SOLUTIONS APPEAR TO
BE TOO DEEP WITH THE UPPER TROUGH AND REMAINS A QUICKER OUTLIER
ALOFT. COMPARING THE VARIOUS OTHER GLOBAL GUIDANCE...HAVE GENERALLY
USED A BLEND OF GFS/ECMWF/UKMET/GEM FOR SFC LOW TRACK/TIMING AND QPF
WITH THIS SYSTEM. CONSENSUS OF THESE SOLUTIONS INITIALLY DEVELOPS AN
ELONGATED SURFACE LOW ACROSS THE LOWER MISSISSIPPI VALLEY TUESDAY
AFTERNOON IN RESPONSE TO THE VIGOROUS MID/UPPER LEVEL WAVE...WHICH
THEN DEEPENS AS IT TRACKS NORTHEAST THROUGH THE MID/UPPER OHIO
VALLEY TOWARD SOUTHWEST PENNSYLVANIA BY WEDNESDAY MORNING.

FAIRLY UNIFORM GUIDANCE SUPPORT FOR A WEST-EAST BAND OF SNOW WILL
DEVELOP TUESDAY AFTERNOON FROM WEST-CENTRAL IL EASTWARD ACROSS
MAINLY THE SOUTHERN HALF OF OUR CWA...WITH INCREASING LARGE SCALE
ASCENT AND HEIGHT FALLS DEVELOPING AHEAD OF THE APPROACHING SHORT
WAVE...AS WELL AS INCREASING MID-LEVEL FRONTOGENESIS AND A FAVORABLE
LOCATION FOR STRONG UPPER DIVERGENCE BENEATH THE RIGHT-ENTRANCE
REGION OF THE UPPER JET MAX (ACTUALLY SOME INDICATION OF A BRIEF
COUPLED JET STRUCTURE BETWEEN LEFT EXIT OF APPROACHING JET STREAK
AND RIGHT ENTRANCE OF STRENGTHENING OVER PRE-EXISTING JET MAXIMA
OVER THE GREAT LAKES REGION). STRONG MID/UPPER LEVEL MOIST ADVECTION
DEVELOPS AHEAD OF THE ADVANCING UPPER TROUGH WITH PRECIPITABLE WATER
VALUES PUSHING 0.50 INCHES INT CENTRAL IL BY 00Z WEDNESDAY...WITH
SOME INDICATION OF MESOSCALE BANDING PRODUCING 0.25 QPF AMOUNTS IN
THAT NARROW AFOREMENTIONED CORRIDOR. BEST JET DYNAMICS AND VORTICITY
ADVECTION SLOWLY MOVE TO THE EAST TUESDAY NIGHT...THOUGH AREA
REMAINS WITHIN DEFORMATION PRECIPITATION SHIELD WHICH EVENTUALLY
PULLS OFF TO THE EAST-NORTHEAST OF THE FORECAST AREA DURING
WEDNESDAY MORNING ALLOWING SNOW TO TAPER OFF. BLENDED QPF AS NOTED
COMBINED WITH 12:1 TO 14:1 SNOW/LIQUID RATIOS THROUGH THE EVENT
YIELDS A DETERMINISTIC SNOWFALL FORECAST RANGING FROM 3-3.5" AROUND
ROCKFORD...TO A STRIPE OF 6-7 INCHES ACROSS THE SOUTHERN TWO TIERS
OF COUNTIES OR SO. THIS MATCHES UP NICELY WITH THE WPC WINTER
WEATHER WEATHER DESK AMOUNTS...THOUGH ULTIMATELY MAY VERY WELL SEE A
TIGHTER GRADIENT ALONG THE NORTHERN EDGE OF THE SNOW. WITH
NORTH-NORTHEAST WINDS OFF THE LAKE WE COULD SEE SOME MINOR
LAKE-ENHANCEMENT INTO NORTHEAST IL...THOUGH NOT A PARTICULARLY
FAVORABLE SET-UP AS IN ADDITION TO H8 TEMPS ONLY AROUND -10/-12C THE
LAKE DOES HAVE CONSIDERABLE ICE COVER OVER THE WESTERN SHORE AREAS
AND CLIMATOLOGICAL COLD WATER TEMPS. WINDS DO LOOK TO GUST ABOVE
20 KT AT TIMES TUESDAY NIGHT-WEDNESDAY MORNING WITH SOME
BLOWING/DRIFTING SNOW LIKELY. SNOWFALL THEN TAPERS OFF AND ENDS BY
LATE WEDNESDAY MORNING...WITH POTENTIAL FOR SOME WEAK LINGERING LAKE
EFFECT SNOW SHOWERS INTO NORTHWEST INDIANA AND THE IL/IN STATE LINE
AREA INTO THE AFTERNOON BUT WITH ONLY MINOR ADDITIONAL ACCUMULATION
EXPECTED DURING THAT TIME. CONTEMPLATED WATCH ISSUANCE FOR SOUTHERN
COUNTIES...THOUGH WITH START OF EVENT STILL LATE 4TH/5TH PERIODS AND
IN AGREEMENT WITH SURROUNDING WFOS TO THE SOUTH/EAST HAVE DECIDED
NOT TO HOIST HEADLINE AT THIS TIME.

Link to comment
Share on other sites

important part from IND

 

...

ADDITIONALLY...DIGGING A LITTLE DEEPER GIVES PAUSE TO THE WEAKER  MODEL PRESENTATION OF THE SYSTEM. Q VECTOR CONVERGENCE REMAINS  FAIRLY STRONG...INDICATING A HEALTHY SYNOPTIC CONTRIBUTION TO  OVERALL SYSTEM FORCING...AND LOW/MID LEVEL MODEL FRONTOGENESIS  FORCING IS QUITE STRONG...ESPECIALLY LATE TUESDAY AND EARLY  TUESDAY EVENING. THIS CONTINUES TO INDICATE THE THREAT OF BANDING  AND THUS LOCALLY HIGHER SNOWFALL AMOUNTS.  
Link to comment
Share on other sites

DVN says around 5" for the I-80 corridor.  I think more like 3-4".  Best snows of 4-7" should line up from far southeast Iowa to Peoria, and through about the northern 1/3 of Indiana.

 

 

DEFORMATION ZONE SETS UP TUESDAY NIGHT INTO WEDNESDAY MORNING. WILL
NEED TO KEEP AN EYE ON THE TIGHTENING GRADIENT AS THE SNOW CONTINUES
TO FALL AND WIND GUSTS INCREASE TO AT LEAST 30 MPH. THIS MAY CAUSE
CONSIDERABLE BLOWING AND DRIFTING SNOW. THE SNOW WILL TAPER OFF
WEDNESDAY MORNING AND I WILL BE GOING DRY IN THE AFTERNOON. SNOW
AMOUNTS SHOULD RANGE FROM AROUND 3 INCHES ALONG HIGHWAY 20 TO AROUND
5 INCHES ALONG THE INTERSTATE 80 CORRIDOR AND 6 TO 7 INCHES IN OUR
SOUTHERN COUNTIES...WHERE THE BETTER MOISTURE WILL EXIST. HOWEVER...
THESE NUMBERS ARE CERTAINLY NOT SET IN CONCRETE JUST YET.
SNOW/LIQUID RATIOS SHOULD RANGE FROM 13:1 TO 15:1 DURING THIS EVENT.

Link to comment
Share on other sites

SREFs came in juicy/snowy here. Only one member below 4" with a mean of 9"

the regular 12z NAM came in with 14-15" for Toledo. So I suppose the bullseye may be up there with more than 9". GFS goes with a broadbrush 5-8" across Ohio. I suppose GFS is seeing reduced possibility of freezing rain/sleet. I think freezing rain and sleet will be a real concern for some of the Ohio Valley. Probably not the north tier.

Link to comment
Share on other sites

sure, as LOT mentioned, northern gradient will likely be tighter than modeled. SE should do ok but far NW could be looking at a DAB situation.

 

Hopefully that high to the north doesn't put too much of a squeeze on the northern end.  So far I'm not seeing too much indicating there's going to be a quick drop off on the north side, but unfortunately it's something to keep an eye on in subsequent runs.

Link to comment
Share on other sites

Well for one nobody on here can see them if you haven't noticed and the guy in charge of WxBell changed something so you couldn't link it.

 

Well if I have something to show then I'll screen capture the image and save it. Thanks for the info.

Link to comment
Share on other sites

Hopefully that high to the north doesn't put too much of a squeeze on the northern end.  So far I'm not seeing too much indicating there's going to be a quick drop off on the north side, but unfortunately it's something to keep an eye on in subsequent runs.

 

totally, it's not showing up on the models but quite a few offices have mentioned as much in their AFDs and if we aren't talking about something more wrapped up (even if south) it makes intuitive sense...especially further east as the vort shears out.

Link to comment
Share on other sites

totally, it's not showing up on the models but quite a few offices have mentioned as much in their AFDs and if we aren't talking about something more wrapped up (even if south) it makes intuitive sense...especially further east as the vort shears out.

 

Might have to issue a pissy-post watch for areas along and north of I-80, with 30% probs north of highway 30. 

Link to comment
Share on other sites

SREF plumes at YYZ are excellent. There's one lone member at 1.3" and then the next lowest one is 4.3". Mean = 7.6". A couple of nut jobs over 12".

 

I haven't had much time for the SREFs in the past but this year, at least locally, they've been excellent.

Euro ENS mean also looking much better compared to the 0z run. Has 0.3-0.4" of QPF for YYZ. Ratio's look to be solidly above 10:1 as well.

Link to comment
Share on other sites

looks like convective feedback issues is causing the problems with wave handlement. You can see this by the models putting the low around the convection to its southeast causing distortions. Thus everything needs to be tighter and further northwest to match the flow.

 

I suspect their will be adjustments once its fully sampled. Models are closing off the Southern stream and thus the northern stream is weak and killed off. 

 

Pattern isnt as progressive as before, so this storm has room to develop more thoroughly. 

Link to comment
Share on other sites

Archived

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

Guest
This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...