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December 25-29th Storm Disco


Chicago Storm

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If the east trend continues... wooh mama.

 

 

 

You okay right now?

Yea im good where I'm at

 

 

 

MESOSCALE PRECIPITATION DISCUSSION 0707

NWS WEATHER PREDICTION CENTER COLLEGE PARK MD

947 PM EST SAT DEC 26 2015

AREAS AFFECTED...SOUTHERN/CENTRAL MO...SOUTHERN IL...SOUTHWEST IN

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 270245Z - 270845Z

SUMMARY...SIGNIFICANT FLASH FLOODING WILL BE POSSIBLE OVERNIGHT AS

VERY HEAVY RAINS CONTINUE TO REPEAT OVER THE SAME AREA.

DISCUSSION...AN EXTENSIVE AXIS OF HEAVY SHOWERS AND THUNDERSTORMS

CONTINUES TO FOCUS ALONG A STATIONARY FRONT OVER THE MID MS VALLEY

AND INTO THE LOWER OH VALLEY OUT AHEAD OF AN AMPLIFYING

TROUGH/CLOSED UPPER LOW OVER THE SOUTHERN HIGH PLAINS.

VERY MOIST AND STRONG DEEP LAYER SOUTH/SOUTHWESTERLY FLOW

CONTINUES TO SURGE ACROSS THE ENTIRE LOWER/MID MS VALLEY REGION

AND INTO THE OH VALLEY FROM THE GULF OF MEXICO AND INTO THE

FRONTAL ZONE. THE SLOWLY APPROACHING UPPER TROUGH/CLOSED LOW IS

CREATING A VERY DIVERGENT FLOW PATTERN ALOFT THROUGHOUT THE REGION

WHERE DEEP CONVECTION IS ONGOING...AND THERE ARE ROBUST H25

RIGHT-ENTRANCE REGION JET DYNAMICS THAT ARE WORKING IN TANDEM WITH

THE STRONG MOISTURE TRANSPORT AND AT LEAST A MODEST DEGREE OF

INSTABILITY.

AREA VWPS SHOW A 40 TO 50 KT LOW LEVEL JET SURGING NORTH INTO THE

FRONT...AND THE GLOBAL MODELS SUSTAIN THIS THROUGHOUT THE NIGHT.

PWATS ARE ALREADY CLOSE TO 1.5 INCHES AND THIS IS 3 TO 4 STD DEV

ABOVE NORMAL FOR THIS TIME OF THE YEAR. THEREFORE...THE

EXPECTATION IS FOR THE CONVECTION TO FOSTER INTENSE RAINFALL

RATES...WHICH WILL APPROACH 2 INCHES/HR LOCALLY.

VERY HEAVY RAINS OF 3 TO 5 INCHES HAVE ALREADY OCCURRED OVER PARTS

OF CENTRAL AND SOUTHWEST MO INTO SOUTH-CENTRAL IL...AND ADDITIONAL

HEAVY RAINS WILL OCCUR OVERNIGHT WITH A VERY GRADUAL EASTWARD

SHIFT IN THE CONVECTIVE AXIS THAT WILL ALSO INCLUDE SOUTHWEST IN.

THE LATEST HRRR SUGGESTS AN AXIS OF 2 TO 3 INCH RAINFALL AMOUNTS

THROUGH 08Z FROM SOUTHWEST MO NORTHEAST INTO SOUTHERN IN AND

GENERALLY RIGHT ALONG THE STATIONARY FRONT WHERE FORCING WILL BE

MAXIMIZED. LOCALLY HEAVIER AMOUNTS OF 4 TO 5 INCHES CANNOT BE

RULED OUT GIVEN SUCH ANOMALOUS MOISTURE TRANSPORT AND STRONG DEEP

LAYER ASCENT.

EXPECT LOCALLY SIGNIFICANT FLASH FLOODING OVERNIGHT GIVEN WET

ANTECEDENT CONDITIONS AND THE EXPECTATION OF CONVECTION TO TEND TO

TRAIN OVER THE SAME AREA.

ORRISON

 

post-3774-0-94100300-1451184782_thumb.gi

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Hard to get ice with heavy precip rates and warm surfaces especially with temps just under freezing

I just don't see more than a tenth or two anywhere outside maybe cyclone77 town

 

 

Reasons to be cautious and not take the maps verbatim, but I think the > 2 tenths area could be more widespread than that.

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Chicagoland/NW IN (away from immediate shore) looks very icy on the 00z RGEM.

 

Low was a bit further east. Cuts up towards Port Washington, WI. Keeps trending that way, there's going to be more real estate ending up with IP and ZR accumulations.

 

0Z GFS

 

post-142-0-58169500-1451188040.gif

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That band could contain some really gusty winds.

 

attachicon.gifPWwind0zNAM.png

 

Looks like the 4km NAM coming in a touch farther east than the 12km.

 

NAM has a very brief period of rain here, everything else is frozen.

New to the forum, and relatively new to the area, so don't understand winters near the lakes yet. Why does this setup not cause LES to the west of the lakes?

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New to the forum, and relatively new to the area, so don't understand winters near the lakes yet. Why does this setup not cause LES to the west of the lakes?

 

Welcome to the sub forum and the region! :)

 

LES (in this case it would be called lake enhanced snowfall) doesn't happen in this setup because the air aloft is warmer than the ground temperature. If you would have been around here during the historic November snowstorm, areas near the lake picked additional snow with an onshore flow. In that setup, the temperature decreased with height all the way up the column.

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Welcome to the sub forum and the region! :)

 

LES (in this case it would be called lake enhanced snowfall) doesn't happen in this setup because the air aloft is warmer than the ground temperature. If you would have been around here during the historic November snowstorm, areas near the lake picked additional snow with an onshore flow. In that setup, the temperature decreased with height all the way up the column.

I have much to learn... :) Thanks! Loving it here so far!

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Latest model trends are indicating a significant thump of snow for the Golden Horseshoe (Toronto) and points eastward along the north shore of Lake Ontario. The 00z GFS dumps 6"+ of snow from Monday evening into early Tuesday morning before changing to ice pellets and rain.

Yes I'm liking the trends.
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