Saturday, March 9, 2013

Upper Mississippi Valley Region Flooding Potential

WX UNIT DISCUSSION 03/09/2013 1900Z

FOR OFFICIAL INFORMATION SEE WWW.WEATHER.GOV 

FOR SEVERE THUNDERSTORM AND TORNADO THREATS SEE WWW.SPC.NOAA.GOV FOR AREAS ACROSS THE CENTRAL PLAINS SOUTHWARD INTO EASTERN TEXAS MOVING EASTWARD TONIGHT

DISCUSSION FOR WI AND ADJOINING STATES

HEAVY RAIN AND FLOODING POTENTIAL MOVING IN TONIGHT AND SUNDAY

UPPER FLOW DEFINED BY LARGE TROUGH REGIME MOVING W TO E ACROSS NOAM.  ONE SHORTWAVE ACROSS SCNTRAL CANADA INTO THE NERN HIGH PLAINS OF MONTANA SPLIT FROM A VERY LARGE TROUGH ALONG THE SWRN CONUS AND SOUTHERN PLAINS STATES.  THE VERY LARGE TROUGH HAS A STRONG SPEED MAX THAT DRAPES AROUND IT FROM SRN CAL INTO NRM MEXICO THAT TURNS NEWD ACROSS TX INTO CENTRAL PLAIN/MID MISS VALLEY REGION AND NOW ENTERING THE UPPER MISS VALLEY.   RIDGING NOTED MAINLY EAST OF MISS RIVER VALLEY.

STRG SFC LOW AT 998 MB DVLPNG OVER SWRN KS NEAR DDC WITH INVERTED TROUGH EXTNDG NE INTO MN TO NEAR INL.  

STRG SRLY LOW/MID LEVEL FLOW WITH GOOD GULF MOISTURE TRANSPORT SPREADING NWWD.  FORCING AND LAPSE RATES ALL LOOK GOOD FOR SVR WX SEE WWW.SPC.NOAA.GOV FOR DETAILS.

WI AND SURROUNDING AREAS:

RAIN NOW SPREADING NEWRD INCLDING SOME EMBEDDED TSTMS ACROSS MISSOURI VALLEY WITH STG WAA REGIME WILL BRING IN AREA OF STEADY RAIN SOMETIMES MODERATE AND OCCASIONALLY HEAVY TONIGHT ACROSS ENTIRE REGION.  WITH CURRENT SNOW PACK THE LAST TWO DAYS HAVE BEEN SLIGHTLY MILD DURING DIURNAL HEATING THERE IS A POTENTIAL FOR SIGNIFICANT FLOODING.

SURPRISED THERE ARE NO FLOOD WATCHES OUT FOR WISCONSIN IOWA, PTNS OF SERN MN, AND NRN IL WHERE THERE IS AMPLE SNOW COVER ESPECIALLY IN THE RIVER FLOOD PRONE REGIONS.  AT LEAST RIVER FLOOD ADVISORIES SHOULD BE POSTED ON THIS.  

I MAY OR MAY NOT COVER THIS ANYMORE SO REVERT TO WWW.WEATHER.GOV FOR MORE INFO AND BE ALERT FOR FLASH FLOODING IN HEAVY RAIN TONIGHT AND SUNDAY IF YOU ARE IN A LOW LYING OR FLOOD PRONE AREA.  

WX UNIT