[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 300619
SWOMCD
SPC MCD 300618 
NDZ000-MTZ000-301015-

MESOSCALE DISCUSSION 2590
NWS STORM PREDICTION CENTER NORMAN OK
1218 AM CST THU DEC 30 2004

AREAS AFFECTED...CENTRAL/ERN MT AND WRN ND

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 300618Z - 301015Z

MIXED WINTER PRECIPITATION WILL DEVELOP ACROSS N-CENTRAL/ERN MT AND
WRN ND THROUGH THE REMAINDER OF THE OVERNIGHT PERIOD. INITIAL
SLEET/FREEZING RAIN SHOULD CHANGE TO SNOW FROM WEST TO EAST ACROSS
MT BETWEEN 06-12Z. POCKETS OF LIGHT FREEZING RAIN AND FREEZING
DRIZZLE APPEAR LIKELY THROUGH 12Z ACROSS WRN ND.

COMPLEX FRONTAL SYSTEM WILL EVOLVE THROUGH 30/12Z ACROSS THE NRN
PLAINS REGION. A 994MB SURFACE CYCLONE NEAR SHERIDAN WY WILL DEEPEN
NEARLY IN PLACE IN RESPONSE TO STRONG UPPER DIFFLUENCE ASSOCIATED
WITH 300MB JET STREAK EXTENDING FROM THE FOUR CORNERS REGION NEWD
INTO SD BY 12Z. A WARM FRONT WILL STRENGTHEN OVERNIGHT ESEWD FROM
THE SURFACE LOW ACROSS THE SRN HALF OF SD...WITH AN E-W BAND OF
850MB WARM ADVECTION DEVELOPING FROM FAR E-CENTRAL MT ACROSS SRN ND.
QUASI-STATIONARY ARCTIC BOUNDARY EXTENDS ACROSS FAR SRN SASKATCHEWAN
SEWD INTO NWRN ND AND ARCS NEWD INTO SERN MANITOBA WITH SURFACE
TEMPERATURES GENERALLY IN THE TEENS AND SINGLE DIGITS NORTH OF THE
BOUNDARY. THE FAR WRN PORTION OF THE ARCTIC FRONT IS SURGING SWD
ALONG THE ERN SLOPES OF THE CONTINENTAL DIVIDE TOWARD GTF AT 0530Z.
ALSO...AN INVERTED TROUGH AXIS IS EVIDENT BETWEEN LWT AND GTF.

DESPITE RELATIVELY DRY LOW-LEVEL CONDITIONS...INCREASING RADAR
TRENDS ARE NOTED ON MOSAIC IMAGERY AT 0530Z FROM NEAR BIL EWD ACROSS
SRN ND. INCREASED ISENTROPIC ASCENT WRAPPING WWD JUST NORTH OF THE
SURFACE CYCLONE THROUGH ERN MT SHOULD RESULT IN DEVELOPMENT OF
FREEZING RAIN OR SLEET BETWEEN 06-09Z. ADDITIONALLY...INCREASING
RADAR TRENDS ARE NOTED IN GTF VICINITY JUST WEST OF INVENTED TROF
AXIS AND IN VICINITY OF APPROACHING ARCTIC FRONT. SNOW/BLOWING SNOW
SHOULD BECOME FOCUSED JUST WEST OF INVERTED TROUGH BY 09Z.
ULTIMATELY...AS 700MB LOW DEEPENS ACROSS ERN MT LATE
TONIGHT...SUFFICIENT UVV AND DYNAMIC COOLING SHOULD OCCUR TO CHANGE
PRECIP TO SNOW BETWEEN 09-12Z ACROSS MUCH OF E-CENTRAL MT. SNOW
SHOULD GENERALLY BE OF LIGHT TO MODERATE INTENSITY WITH MAX SNOWFALL
RATES IN 0.5-1"/HR RANGE. FURTHER EAST...BAND OF LIGHT FREEZING
RAIN/DRIZZLE SHOULD EXIST ALONG I-94 CORRIDOR IN WRN ND. ETA APPEARS
TO HAVE INITIALIZED ARCTIC BOUNDARY TOO FAR SOUTH ACROSS ND...AND
PREFER 03Z RUC SOLUTION HOLDING SURFACE TEMPERATURES IN THE MID 20S
IN THIS AREA WITH MARGINAL DEEP LAYER MOISTURE FOR OCCASIONAL
FREEZING RAIN THROUGH 12Z.

..BANACOS.. 12/30/2004

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A 
SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 00-01 UTC...
06-07 UTC...12-13 UTC...AND 18-19 UTC AS SIGNIFICANT SHORT
RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
USED FROM DECEMBER 1 THROUGH FEBRUARY 28.

ATTN...WFO...BIS...BYZ...GGW...TFX...

46260360 46190511 46050738 46070916 46981076 47131172
47431240 48141263 48741194 48971080 48791023 48460992
48060924 48090810 48020619 48100468 48110342 48000198
47690115 47330091 46640087 46370160