[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 210423
SWOMCD
SPC MCD 210422 COR
TNZ000-KYZ000-INZ000-ILZ000-211015-

MESOSCALE DISCUSSION 0081
NWS STORM PREDICTION CENTER NORMAN OK
1022 PM CST FRI FEB 20 2015

AREAS AFFECTED...PORTIONS OF THE TN AND OH VALLEYS

CONCERNING...WINTER MIXED PRECIPITATION

VALID 210422Z - 211015Z

CORRECTED FOR REMOVING ERRONEOUS ALERTED WFOS.

SUMMARY...AREAS OF FZRA...AT TIMES MIXED WITH SLEET AND SNOW LATE
THIS EVENING...WILL CONTINUE ACROSS THE AREA. ICE ACCRETION RATES UP
TO 0.05-0.10 IN/HR WILL BE POSSIBLE.

DISCUSSION...04Z RADAR MOSAIC INDICATES A RELATIVELY LARGE AREA OF
WINTER MIXED PCPN ACROSS PORTIONS OF THE OH AND TN VALLEYS THIS
EVENING. THE ERN EXTENT OF THIS REGION IS CHARACTERIZED BY A MIX OF
PRIMARILY SNOW AND SLEET...WHILE FZRA IS THE PREDOMINANT TYPE
FARTHER WEST /APPROX BWG-BNA LINE AND VICINITY/. RECENT METARS
INDICATE THE AREA OF FZRA IS ASSOCIATED WITH ICE ACCRETION RATES
UPWARDS OF 0.10 IN/HR.

IN CONCERT WITH LARGE-SCALE FORCING FOR ASCENT FROM AN APPROACHING
SHORTWAVE TROUGH ACROSS THE PLAINS...INCREASING ADIABATIC ASCENT
FROM A 70-KT LLJ WILL PROMOTE ANOTHER ROUND OF PCPN OVERSPREADING
THE AREA FROM THE WEST AFTER 05-06Z. INDEED...SFC PRES FALLS OF
1-1.5 MB PER HR ACROSS NE AR /PER 03Z SFC ANALYSIS/ ARE A REFLECTION
OF THIS ROBUST WAA ALOFT...AND A CONTINUATION OF ICE ACCRETION RATES
OF 0.05-0.10 IN/HR IS FORECAST THRU APPROXIMATELY 10Z AS MORE FZRA
SPREADS NORTHEAST ACROSS THE MCD AREA. FURTHERMORE...WHILE NERN
PORTIONS OF THIS AREA ARE CURRENTLY EXPERIENCING A MIXTURE OF SLEET
AND SNOW...THE AFOREMENTIONED STRONG WAA SHOULD SUPPORT THESE
P-TYPES MIXING WITH OR CHANGING OVER ENTIRELY TO FZRA AFTER 06Z. AS
SUCH...ICE ACCRETION RATES OF SEVERAL HUNDREDTHS OF AN INCH PER HOUR
CAN BE EXPECTED ACROSS PORTIONS OF CNTRL/ERN KY...NERN TN...AND SRN
INDIANA LATE TONIGHT AS WELL.

..PICCA/EDWARDS.. 02/21/2015

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

ATTN...WFO...MRX...JKL...ILN...LMK...OHX...IND...PAH...MEG...

LAT...LON   36518882 37518858 38308804 38518712 38598634 38618569
            38558513 38188408 37228369 36408395 35748430 35528530
            35468687 35528876 35958895 36518882



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