Mesoscale Discussion 68

Issued

Feb 1, 2011, 11:42 AM CST (17:42 UTC)

Expired

Feb 1, 2011, 4:45 PM CST

In force

5 hr

Issued by

the Storm Prediction Center

The Evansville,IN radar (KVWX), 88 km from the middle of the area, began a volume at 17:41 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

816 
ACUS11 KWNS 011743
SWOMCD
SPC MCD 011742
INZ000-ILZ000-MOZ000-012245-

MESOSCALE DISCUSSION 0068
NWS STORM PREDICTION CENTER NORMAN OK
1142 AM CST TUE FEB 01 2011

AREAS AFFECTED...PORTIONS OF SRN/E-CNTRL MO...CNTRL IL...CNTRL IND

CONCERNING...WINTER MIXED PRECIPITATION

VALID 011742Z - 012245Z

MODERATE TO HEAVY MIXED PRECIPITATION WILL EXPAND EWD ACROSS
PORTIONS OF THE LOWER GREAT LAKES AND OHIO VALLEY REGION THROUGH
22Z. SIGNIFICANT ICING...WITH FREEZING RAIN RATES AOA 0.25 INCH PER
3 HOURS...WILL BE A CONCERN IN THE SRN HALF OF THE DISCUSSION
AREA...WITH SLEET EXPECTED FURTHER NORTH.

A POWERFUL EXTRATROPICAL CYCLONE CONTINUES TO MATURE OVER THE CNTRL
CONUS...WITH A WELL-DEFINED/INTENSE WARM CONVEYOR BELT IN THE ERN
SEMICIRCLE OF THE CYCLONE. THE 15Z RUN OF THE RUC INDICATES A SLY
850-MB JET MAX WITH CORE WINDS OF 70 KT OVER PORTIONS OF THE LOWER
OH VALLEY AND MID-SOUTH. THIS IS SUPPORTING STRONG NWD TRANSPORT OF
DEEP-LAYER MOISTURE...WITH AMSU/SSMI TOTAL PRECIPITABLE WATER
PRODUCT INDICATING AN INFLUX OF PWAT VALUES AROUND 1.5 INCHES NOSING
INTO THE LOWER MS VALLEY REGION. DEEP-LAYER ASCENT ASSOCIATED WITH
THE WARM CONVEYOR BELT RISING ATOP THE COLD AIR MASS ENTRENCHED
ACROSS THE OHIO VALLEY REGION WILL BE AUGMENTED BY INTENSE
UPPER-LEVEL DIVERGENCE EXPECTED TO RESULT FROM A COUPLED JET STREAK
STRUCTURE LATER THIS AFTERNOON. AS PRECIPITATION FALLS INTO A
NEAR-SURFACE SUB-FREEZING LAYER AT LEAST 60 STATUTE MILES NORTH OF
THE OH RIVER...MIXED PRECIPITATION TYPES ARE EXPECTED THIS
AFTERNOON.

ACROSS THE SRN HALF OF THE DISCUSSION AREA WHERE LOW-LEVEL WARMING
WILL BE STRONGEST...TEMPERATURES AOA 3C IN THE ELEVATED WARM LAYER
WILL SUPPORT COMPLETE MELTING OF HYDROMETEORS. FREEZING RAIN IS
ANTICIPATED IN THIS REGION...AS THE PRECIPITATION INTERACTS WITH
SUB-FREEZING SFC TEMPS. HEAVY FREEZING RAIN WILL BE POSSIBLE...AS
THE 12Z NAM MODEL INDICATES UPRIGHT INSTABILITY ENTERING THE REGION
IN ASSOCIATION WITH THE WARM CONVEYOR BELT. THE ASSOCIATED
CONVECTIVE ENHANCEMENT...POTENTIALLY ACCOMPANIED BY LIGHTNING...WILL
ALLOW LIQUID-EQUIVALENT TO EXCEED 0.25 INCH PER 3 HOURS PER THE HRRR
MODEL. THIS WILL LIKELY RESULT IN SIGNIFICANT ICING.

ACROSS THE NRN HALF OF THE DISCUSSION AREA...TEMPERATURES IN THE
ELEVATED WARM LAYER ARE EXPECTED TO REMAIN BELOW 3C...ALLOWING ONLY
PARTIAL HYDROMETEOR MELTING...WITH MAINLY SLEET EXPECTED. THE NAM
MODEL INDICATES SLANTWISE INSTABILITY SPREADING E/NEWD ACROSS THIS
REGION...SUGGESTING THE POTENTIAL FOR MESOSCALE BANDING AND LOCALLY
HEAVY SLEET RATES.

..COHEN/ROGERS.. 02/01/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...ILN...LMK...IWX...IND...PAH...LOT...ILX...LSX...
SGF...

LAT...LON   40218485 39278488 38868546 38718701 38518807 37718987
            37039099 36679165 36739239 37499251 38139199 38999083
            40218832 40778565 40218485

Mesoscale Discussions in Indiana, 2011Mesoscale Discussions in Illinois, 2011Mesoscale Discussions in Missouri, 2011Every mesoscale discussion in 2011

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.