SPC MD 1821

MD 1821 CONCERNING FREEZING RAIN FOR FAR EASTERN ND...NORTHWESTERN MN

MESOSCALE DISCUSSION 1821
NWS STORM PREDICTION CENTER NORMAN OK
0150 AM CST TUE NOV 22 2016

AREAS AFFECTED...FAR EASTERN ND...NORTHWESTERN MN

CONCERNING...FREEZING RAIN 

VALID 220750Z - 220945Z

SUMMARY...FREEZING RAIN RATES 0.05-0.10 INCH PER 3 HOURS WILL
PROBABLY OCCUR DURING THE 08-12 UTC PERIOD BEFORE SURFACE
TEMPERATURES WARM AND A TRANSITION TO RAIN OCCURS.

DISCUSSION...RADAR MOSAIC SHOWS A SHIELD OF LIGHT REFLECTIVITY
ACROSS THE RED RIVER VALLEY AS OF 0745 UTC.  A LOW-LEVEL
WARM-AIR-ADVECTION REGIME IS IMPLIED BY A VEERING WIND PROFILE AT
KABR.  STRONG SOUTHERLY FLOW AT H95-H85 AROUND 40 KT IS SERVING TO
ADVECT INCREASING MOISTURE INTO THE RED RIVER VALLEY EARLY THIS
MORNING.  A MODIFYING CONTINENTAL-POLAR AIRMASS OVER THE REGION
FEATURES AN INITIALLY DRY 0-1 KM LAYER.  FORECAST SOUNDINGS AND
UPSTREAM OBSERVATIONS SUGGEST THIS LAYER WILL SATURATE AND CONTINUED
ISENTROPIC LIFT WILL SUPPORT PRECIPITATION.  BECAUSE OF WET-BULB
COOLING PROCESSES...SURFACE TEMPERATURES IN THE LOWER TO MIDDLE 30S
DEG F WILL LIKELY COOL INTO THE 30-32 DEG F RANGE.  AS A RESULT...
FREEZING RAIN RATES OF 0.05-0.10 INCH PER 3 HOURS ARE EXPECTED EARLY
THIS MORNING BEFORE BOTH PRECIPITATION DEPARTURE AND WARMING SURFACE
TEMPERATURES COMBINE TO END THE FREEZING RAIN.

..SMITH.. 11/22/2016

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

ATTN...WFO...FGF...

LAT...LON   46949681 48989745 48989625 48259559 47229537 46809613
            46949681 

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