SPC MESOSCALE DISCUSSION 2287 FOR ERN SD / SWRN AND WCNTRL
MN
CONCERNING...HEAVY SNOW AND NEAR BLIZZARD CONDITIONS...

A PROLONGED PERIOD OF SNOWFALL RATES AT 1-2 INCHES PER HOUR
ARE
EXPECTED TO BE CONCENTRATED OVER ERN SD INTO SWRN/WCNTRL MN
THROUGH
THIS AFTERNOON.

15Z SURFACE ANALYSIS PLACES THE SURFACE LOW OVER EXTREME
SCNTRL NEB
WITH PERSISTENT PRESSURE FALLS OVER WRN IA DURING THE LAST
SEVERAL
HOURS. OBJECTIVE ANALYSES/12Z ETA/RUC MODELS SUGGEST THE
SURFACE
LOW WILL TRACK TOWARD SWRN IA BY 27/00Z...AS THE UPPER LOW
LIFTS
SLOWLY NEWD. 12Z UPPER AIR ANALYSIS SHOWS A STRONG 850 MB
THERMAL
GRADIENT OVER ERN SD INTO CENTRAL MN. MODELS INDICATE
PERSISTENT
FRONTOGENETICAL FORCING OVER SERN/ERN SD INTO SWRN/WCNTRL MN
THROUGH AT LEAST 00Z...SUPPORTING HEAVY SNOWFALL RATES. A
TIGHT
SURFACE PRESSURE GRADIENT WITH THE SURFACE LOW WILL RESULT
IN
BLOWING SNOW WITH NEAR-BLIZZARD CONDITIONS FROM ERN SD INTO
EXTREME
WRN MN WHERE SUSTAINED NNELY WINDS AT 20-30 KT WILL REDUCE
VISIBILITIES TO LESS THAN 1/4 MILE.
 

..PETERS.. 11/26/01

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




000
ACUS11 KWNS 262149
SWOMCD
SPC MCD 262149
SDZ000-MNZ000-270200-

SPC MESOSCALE DISCUSSION 2290 FOR ERN SD INTO CENTRAL MN
CONCERNING...HEAVY SNOW...

SNOWFALL RATES FROM 1-1.5 INCH PER HOUR WILL PERSIST OVER
ERN SD
AND CONTINUE TO DEVELOP ENEWD INTO CENTRAL MN.

MESO-ANALYSES SHOW SURFACE LOW OVER SERN NEB WITH PRESSURE
FALL
CENTER OVER SRN MN/EXTREME NRN IA. THESE SURFACE FEATURES
AGREE
FAIRLY WELL WITH ETA/RUC MODEL FORECASTS WITH SURFACE SYSTEM
EXPECTED TO TRACK INTO NW/NCNTRL IA BY 06Z. DRY SLOT ON VIS
SATELLITE IMAGERY HAS MOVED INTO SERN SD AND TO THE SWRN
MN/NWRN IA
BORDER DURING THE LAST FEW HOURS...WITH DECREASING SNOWFALL
RATES
AT FSD. 18Z ETA APPEARS TO HAVE THE BEST AGREEMENT WITH THE
DRY
SLOT AND LOCATION OF HEAVY SNOW POTENTIAL. SATELLITE TRENDS
SUGGEST HEAVIER SNOWFALL RATES TO REMAIN OVER ERN SD /TO THE
WEST
AND NORTH OF FSD/...WITH RATES EXPECTED TO INCREASE OVER
NERN SD
INTO CENTRAL MN DURING THE NEXT FEW HOURS.
 

..PETERS.. 11/26/01

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



000
ACUS11 KWNS 270102
SWOMCD
SPC MCD 270101
SDZ000-NEZ000-IAZ000-MNZ000-270630-

SPC MESOSCALE DISCUSSION 2294 FOR SERN SD...EXTREME NERN
NEBRASKA...NWRN IA...AND SWRN MN.
CONCERNING...WINTER MIXED PRECIPITATION...

A PERSISTENT MIX OF MODERATE TO HEAVY SNOW/SLEET/FREEZING
RAIN WILL
AFFECT THE AREA AROUND SIOUX FALLS THROUGH THE EVENING
HOURS.
WATER EQUIVALENT ACCUMULATIONS OF 0.10-0.20 IN/HR WILL BE
POSSIBLE
THROUGH 06Z.

E-W ORIENTED BAND OF CONVECTIVE PRECIPITATION CONTINUE ITS
SLOW
DRIFT NWD...AND WILL AFFECT THE SIOUX FALLS AREA BY 03Z.
THROUGH
06Z...A MIXTURE OF FREEZING RAIN AND SLEET WILL BE LIKELY
FROM FSD
EWD...WHERE ATMOSPHERE HAS DRIED ALOFT DUE TO DRY SLOT. RAIN
WILL
CHANGE TO FREEZING RAIN OVER NWRN IA...WHERE LOW LEVEL CAA
WILL
INCREASE AS WINDS BACK. BEST CHANCE FOR ADDITIONAL HEAVY
SNOW WILL
BE OVER THE WRN HALF OF THE DISCUSSION AREA...WHERE A DEEPER
LAYER
OF SATURATION COEXISTS WITH LIFT THROUGHOUT THE FAVORABLE
SNOW
MAKING LEVELS OF THE ATMOSPHERE. THE ENTIRE AREA SHOULD
CHANGE TO
ALL SNOW BY 08Z.
 

..JEWELL.. 11/27/01

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


000
ACUS11 KWNS 270753
SWOMCD
SPC MCD 270752
WIZ000-MNZ000-271200-

SPC MESOSCALE DISCUSSION 2300 FOR ECNTRL MN INTO NRN WI
CONCERNING...HEAVY SNOW...

SNOWFALL RATES WILL LIKELY INCREASE WITH RATES OF 1-1.5
INCHES PER
HOUR ACROSS PORTIONS OF ECNTRL MN INTO NRN WI BY 0900 UTC
AND
CONTINUE THROUGH AT LEAST 12 UTC.

MESOANALYSIS PLACES SURFACE LOW OVER NWRN IA ATTM...WITH THE
NOSE
OF THE WARM CONVEYOR BELT INTO SRN WI. BAND OF ENHANCED PCPN
HAS
BEEN ROTATING NWD THROUGH SRN MN AND CNTRL WI OVER THE PAST
HOUR
WITH RAIN RATES OF 0.05-0.10 INCHES PER HOUR. THIS BAND WILL
LIKELY MOVE NWD...THEN BECOME QUASISTATIONARY IN ROUGHLY A
40 MILE
WIDE CORRIDOR 40 SSE AXN-60 S DLH-40 S IWD-NEAR IMT. 06 UTC
RUC40
AGREES WITH THE LATEST ETA RUN IN DEVELOPING A REGION OF
LOW-
MIDLEVEL FRONTOGENESIS IN THIS ZONE WHERE SURFACE
TEMPERATURES ARE
IN THE UPPER 20S TO AROUND 30. SPC/HPC EXPERIMENTAL
PRECIPITATION
TYPE ALGORITHM FORECASTS THE MOST PROBABLE PCPN TO BE
SNOW...WITH
PERHAPS A MIX OF SLEET/RAIN MIXING ALONG THE SRN PERIPHERY
FROM
MIC-RPD-30 SW IMT.
 

..RACY.. 11/27/01