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January 31-February 2 Historic Winter Storm part 6


Hoosier

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updated milwuakee

FOR TUE NT AND WED THE LATEST NAM HAS CONTINUED ITS NORTH AND

SOUTH OSCILLATION WITH THE TRACK OF THE LOW FROM MODEL RUN TO

MODEL RUN. IT NOW IS MORE SOUTH...RIGHT ALONG THE OHIO RIVER BUT

NOT CONCERNED WITH FCST. CURRENT QPF IS NEAR A BLEND OF THE 12Z

GFS AND 12Z ECMWF. SNOW RATIOS MAY NEED TO BE ADJUSTED DOWNWARD AS

UWM NEURAL NETWORK IS SHOWING HEAVIER RATIOS DUE TO STRONG WIND

SPEEDS. AVERAGE RATIOS FOR TUE NT-WED MAY BE CLOSER TO 13 TO 1 IN

FAR SE WI TO 15-18 TO 1 OVER SOUTH CENTRAL WI. THIS LOWERS OUR

SNOW TOTALS BY 4-5 INCHES IN SE WI. WILL LET MIDNIGHT SHIFT

ANALYZE 00Z MODELS AND DECIDE ON NEW QPF AND SNOW AMOUNTS USING

LOWER SNOW TO LIQUID RATIOS. LAKE ENHANCEMENT CONTRIBUTION WILL

HAVE TO BE DETERMINED AS WELL.

Does it make sense for the snow ratios to be this low? I know the winds will be strong, but they mentioned in their previous discussion that models were using a 20:1 or even up to a 25:1 ratio, and they took 15:1 to be conservative.

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I stepped outside about 30 minutes ago and was surprised at how gusty it had become. We are getting a good breeze out of the NE with gusts approaching 20.

I have noticed that both the NAM and GFS have now shifted the freezing rain zone further south and east - very close to Perryville, MO and Cape Girardeau, MO into southern Illinois. The runs have slowly been shifting south and east for the last 24 hours.

This could be a signal that the models are still not handling the low level cold bleed into these areas. Even though the storm track continues to shift slightly north and west the models are shifting the freezing rain zone further south and east.

Just something I have been paying attention to -

Models seem to have a difficult time with low - shallow cold air. One or two counties difference will mean the difference between significant ice vs just plain cold rain. Tough forecast.

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Does it make sense for the snow ratios to be this low? I know the winds will be strong, but they mentioned in their previous discussion that models were using a 20:1 or even up to a 25:1 ratio, and they took 15:1 to be conservative.

I think a 15-18:1 is very reasonable. Winds will be awfully strong, especially for them along the lake shore. And measurement isn't exactly going to be a perfect science either.

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Yes, looks unrealistic.

The NAM is back to that flat track. I am not buying that for a second. Needs to have that hook, especially with the type of cyclogenesis we're dealing with. Frustrating model...

On a more important note, the 21Z SREF members continue to converge on a solution. A good deal of the ETA members are now further NW and are close to agreeing with the RSM, ARW and NMM members. The mean is also sharper with the northern cutoff, which matches with the strong high to the north and northwest of the system.

Agreed. The NAM flat track looks very unrealistic.

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I have noticed that both the NAM and GFS have now shifted the freezing rain zone further south and east - very close to Perryville, MO and Cape Girardeau, MO into southern Illinois. The runs have slowly been shifting south and east for the last 24 hours.

This could be a signal that the models are still not handling the low level cold bleed into these areas. Even though the storm track continues to shift slightly north and west the models are shifting the freezing rain zone further south and east.

Just something I have been paying attention to -

Models seem to have a difficult time with low - shallow cold air. One or two counties difference will mean the difference between significant ice vs just plain cold rain. Tough forecast.

Thanks for the info. Very helpful for us in that neck of the woods.

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