Mesoscale Discussion 110

Issued

Feb 19, 2011, 11:25 PM CST (05:25 UTC)

Expired

Feb 20, 2011, 4:30 AM CST

In force

5 hr

Issued by

the Storm Prediction Center

The Sioux Falls radar (KFSD), 70 km from the middle of the area, began a volume at 05:31 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.

987 
ACUS11 KWNS 200525
SWOMCD
SPC MCD 200525 
MNZ000-IAZ000-SDZ000-NEZ000-201030-

MESOSCALE DISCUSSION 0110
NWS STORM PREDICTION CENTER NORMAN OK
1125 PM CST SAT FEB 19 2011

AREAS AFFECTED...PARTS OF NRN NEB/SRN SD EWD TO SWRN MN/EXTREME NWRN
IA

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 200525Z - 201030Z

WINTRY PRECIPITATION IS EXPECTED TO DEVELOP NEWD ACROSS NORTH
CENTRAL NEB/SOUTH CENTRAL SD BETWEEN 06-09Z...AND THEN EWD INTO SWRN
MN AND FAR NWRN IA MAINLY AFTER 09Z.  WEAK ELEVATED INSTABILITY WILL
SUPPORT THE POTENTIAL FOR TSTMS WHICH WILL INCREASE THE RATE OF
FREEZING RAIN AND SLEET.  FREEZING RAIN WITH RATES 0.15 INCH PER 3
HOUR SHOULD REMAIN CONFINED TO A 50 MILE WIDE CORRIDOR EXTENDING
FROM LOGAN COUNTY NEB TO TURNER COUNTY SD AND THEN EWD INTO FAR NWRN
IA AND ADJACENT COUNTIES IN SWRN MN.  MODELS SUGGEST AN AREA
EXTENDING 60-80 MILES NORTH OF THE FREEZING RAIN SHOULD CONSIST OF
PREDOMINANTLY SLEET FROM THE ONSET OF PRECIPITATION THROUGH AT LEAST
12Z.  HEAVY SLEET RATES WILL BE POSSIBLE...ESPECIALLY WITH ANY TSTMS
THAT DEVELOP.

SURFACE THETA/THETAE ANALYSES INDICATED A BAROCLINIC ZONE EXTENDING
EWD FROM SERN WY INTO CENTRAL NEB...THEN NEWD TO SWRN/SRN MN AND FAR
NWRN/NRN IA.  MODELS MAINTAIN THIS BOUNDARY POSITION THROUGH
12Z...WITH THIS FEATURE GENERALLY COINCIDENT WITH THE SURFACE
FREEZING LINE.  AS SUCH...THIS BOUNDARY WILL BE THE SRN EXTENT OF
THE FREEZING RAIN THREAT THROUGH THE OVERNIGHT PERIOD.  PERSISTENT/
EXPANDING AREA OF LIGHTNING ACROSS ERN CO AND COOLING CLOUD TOPS PER
IR SATELLITE IMAGERY OVER ERN CO INTO WRN/CENTRAL NEB ARE LIKELY
INDICATIVE OF THE STRONG DEEP LAYER ASCENT SPREADING NEWD TONIGHT
PER A LEAD SHORTWAVE TROUGH OVER CENTRAL CO.  AIR MASS MOISTENING IS
UNDERWAY ACROSS THE DISCUSSION AREA ATTENDANT TO INCREASING WAA
REGIME ALONG NOSE OF STRENGTHENING SRN-CENTRAL PLAINS LLJ AND WITHIN
EXIT REGION OF STRONG SWLY UPPER LEVEL JET NOSING INTO THE CENTRAL
PLAINS.

PRECIPITATION RATES...ALTHOUGH GENERALLY LIGHT AT THE ONSET ACROSS
SWRN/CENTRAL NEB...ARE EXPECTED TO INCREASE OVERNIGHT INTO EARLY
SUNDAY MORNING AS DEEP LAYER ASCENT BECOMES MAXIMIZED ACROSS THE
DISCUSSION AREA PER AFOREMENTIONED EVOLUTION OF MASS FIELDS. 
FORECAST SOUNDINGS WITHIN THE EXPECTED FREEZING RAIN CORRIDOR
SUGGEST A 3-4 DEGREE MAXIMUM INCREASE ABOVE 0 C IN THE 850-700 MB
LAYER THROUGH 12Z.  THIS WILL BE MORE THAN SUFFICIENT TO SUPPORT
FREEZING RAIN...GIVEN SUB-FREEZING SURFACE TEMPERATURES.  FARTHER
N...VERTICAL THERMAL PROFILES SUPPORT MAINLY SLEET.  BY 12Z...AN
INCREASE IN LOW LEVEL CAA WILL BE DEVELOPING FROM WNW-ESE ACROSS
WRN-CENTRAL NEB AS A SURFACE LOW MOVES INTO FAR SWRN NEB/NWRN KS. 
THIS TREND MAY SUPPORT A TRANSITION FROM SLEET TO SNOW ACROSS
CENTRAL SD.

..PETERS.. 02/20/2011

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

ATTN...WFO...MPX...DMX...FSD...OAX...ABR...LBF...UNR...

LAT...LON   44369813 44429670 44309533 44039439 43659354 43169350
            42989432 43149591 42679727 42219805 41539972 41560119
            42200150 42860171 44049959 44369813

Mesoscale Discussions in South Dakota, 2011Mesoscale Discussions in Nebraska, 2011Mesoscale Discussions in Iowa, 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.