Jump to content
  • Member Statistics

    17,606
    Total Members
    7,904
    Most Online
    ArlyDude
    Newest Member
    ArlyDude
    Joined

Dec 11-13 MW/Lakes/OV Snow Event? Part III


Chicago Storm

Recommended Posts

more energy hanging back

may not mean a damn thing...

also that lobe coming around the vortex in canada looks a little more juiced

I think you should be real careful at looking at upper level vorticity fields alone and coming to a conclusion regarding intensity of a system/upper level baroclinic wave as a lot is happening dynamically to produce those vorticity fields. In this case, prolly better looking at surface pressure maps with strong cyclogenesis such as this. Also, we are in the time frame (36+ hours) where differences are more likely the result of initial conditions...for the NAM...this is about as similar as it gets from one run to the next.

Link to comment
Share on other sites

  • Replies 994
  • Created
  • Last Reply

IWX AFD:

LONG TERM

SATURDAY THROUGH THURSDAY.

STORM SYSTEM TO AFFECT MUCH OF THE EASTERN US FOR THE UPCOMING

WEEKEND REMAINS THE MAIN FOCUS...AND CAUSE FOR MANY HEADACHES AS

MODELS REMAIN SEPARATED IN THEIR SOLUTIONS FOR THE DEVELOPMENT AND

INTENSIFICATION OF THE SYSTEM. PRIOR TO 18Z SAT...MODELS AGREE ON

INITIAL UPPER SYSTEM AND SFC LOW DEVELOPMENT BEING NW OF THE

FORECAST AREA SOMEWHERE BETWEEN NORTHERN ILLINOIS AND NE IOWA.

MAJORITY OF MODELS ALSO INDICATE A WEAKER SFC TROUGH FURTHER SOUTH

AT THE SAME TIME. WHERE THE CONCERNS LIE WHETHER ANY PHASING

OCCURS OF THE ENERGY...WHERE AND WHEN.

FOR SATURDAY...INCREASING SOUTHERLY FLOW SHOULD ALLOW 850 MB TEMPS

TO CLIMB ABOVE 0 C. PRECIP SHOULD BEGIN TO OVERSPREAD WESTERN AREAS

DURING THE AFTERNOON WITH A MIX OF RAIN OR SNOW. CONCERNS EXIST

REGARDING BOUNDARY LAYER TEMPS WITH RECENT COLD WEATHER AND SNOW

PACK WHICH COULD KEEP TEMPS COLDER THAN FORECAST. THESE CONCERNS

CONTINUE INTO SATURDAY NIGHT. CONSIDERING SNOW PACK IS NOT OVERLY

DENSE IN MOST AREAS...WARMER HIGHS SHOULD OCCUR. NO CHANGES MADE TO

SATURDAY GRIDS FOR THE MOMENT.

SATURDAY NIGHT INTO SUNDAY STILL APPEARS TO BE THE MAIN TIME FRAME

FOR PRECIP ACROSS THE AREA WITH SAT NGT MORE WAA PRECIP AHEAD OF THE

LOW AND THEN POTENTIAL FOR DEFORMATION/LAKE ENHANCEMENT BEHIND THE

LOW ON SUNDAY. NAM12 WAS MORE AGGRESSIVE ON THE DEFORMATION/LAKE

ENHANCEMENT IN PAST RUNS BUT 12Z RUN HAS PLACED EMPHASIS ON WAA VS

DEFORMATION. THE ECMWF TRACKS THE LOW ACROSS THE AREA ALONG WITH 700

MB LOW WHICH WOULD BE FAVORABLE FOR HEAVIER SNOW...ASSUMING A MORE

SOUTHERLY TRACK. WHAT REMAINS CONCERNING IS EVOLUTION OF THE MAIN

SYSTEM AND THAT AFTER THE INITIAL SURGE OF WAA PRECIP WE END UP

GETTING SPLIT WITH LIMITED DEFORMATION AND LAKE EFFECT BEHIND THE

SYSTEM. THIS CONCERN IS ECHOED SOMEWHAT BY MODEL DISCUSSION FROM

HPC. ONE WOULD HOPE THE MODELS WOULD HAVE BEEN LINED UP WITH THIS

BUT SINCE THEY ARE NOT HAVE NO CHOICE BUT TO RETAIN PREVIOUS GRIDS.

WHILE WE APPEAR TO BE THE OUTLIER IN TERMS OF FREEZING RAIN

POTENTIAL...DO FEEL THAT THE CONCERN IS THERE...AS NOTED

ABOVE...REGARDING BOUNDARY LAYER TEMPS AND WEDGE OF WARMER AIR PRIOR

TO ARRIVAL OF COLD AIR LATE SATURDAY NIGHT AND SUNDAY. FEEL THAT

BEST POTENTIAL FOR PRECIP REMAINS SAT NGT WITH WAA PRECIP SO WILL

INCREASE TO 70 POPS WITH SUNDAY POPS LEFT ALONE FOR NOW.

MODELS DO AT LEAST AGREE ON ONE PART OF THE EXTENDED...THE SURGE OF

COLD AIR BEHIND THE SYSTEM SUNDAY/SUNDAY NIGHT INTO TUESDAY AND

POSSIBLY BEYOND. BY 06Z MONDAY...MODELS HINT AT 850 MB TEMPS FROM

-14 TO -16 C. THIS WILL RESULT IN A RATHER COLD PERIOD WITH HIGHS

ONLY IN THE UPPER TEENS TO LOWER 20S AND OVERNIGHT LOWS POSSIBLY

FLIRT WITH ZERO. REGARDLESS OF WHICH SOLUTION COMES TRUE IN THE

MODELS (NORTHERN LOW VS EAST COAST STORM) NORTH TO NORTHWEST FLOW

WILL SETUP ACROSS THE GREAT LAKES ONCE AGAIN. THIS WILL RESULT IN AN

INCREASED THREAT FOR LAKE EFFECT SNOWS FOR A PROLONGED PERIOD. WHILE

LITTLE CONFIDENCE CAN BE GAINED FROM COARSER MED RANGE

MODELS...HINTS OF ANOTHER LAKE SUPERIOR CONNECTION DO EXIST WHICH

COULD RESULT IN POTENTIAL HEADLINES FOR THE LAKE EFFECT. OF CONCERN

IN THIS SITUATION IS A FARTHER EAST SOLUTION OF THE LOW

INTENSIFICATION COULD ALLOW FOR ENTRAINMENT OF DRIER AIR ACROSS THE

LAKES WHICH MAY REDUCE POTENTIAL. PREVIOUS GRIDS DEFINITELY

REASONABLE AT THIS POINT WITH AT LEAST SOME SNOW SHOWERS EXPECTED IN

THE WAKE OF THE SYSTEM. CHANGES WILL BE NEEDED AS WE EDGE CLOSER TO

THE EVENT. SHOULD BE RATHER WINDY ON SUNDAY POSSIBLY INTO SUNDAY

NIGHT WHICH WOULD BLOW AROUND ANY SNOWFALL. HAVE ADDED MENTION OF

AREAS OF BLOWING SNOW SUNDAY TO COVER THIS.

RIDGING BEGINS TO MOVE IN BY TUES NGT/WEDS WHICH SHOULD CUT OFF THE

BULK OF ANY LAKE EFFECT AND ALLOW SOME MODERATION IN TEMPS. THIS

MODERATION MAY BE HAMPERED BY REFRESHED SNOW BACK AND COLD BOUNDARY

LAYER. AS A RESULT..HAVE UNDERCUT HPC GUIDANCE FOR OVERNIGHT LOWS

WEDS NGT BY SEVERAL DEGREES AND SLIGHT CUT IN HIGHS THURSDAY.

Link to comment
Share on other sites

She's warming up.

Maybe for you. For WI and MN this is going to rock.

Lesson for this storm is that models suck when it comes to phasing solutions. Sometimes they get it right (GFS nailed the October bomb way before EURO), but sometimes they are dead wrong. Small discrepancies in timing and features have a huge impact on phasing solutions.

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...