ACUS11 KWNS 061736
SWOMCD
SPC MCD 061736
NYZ000-062130-

MESOSCALE DISCUSSION 0013
NWS STORM PREDICTION CENTER NORMAN OK
1136 AM CST TUE JAN 06 2004

AREAS AFFECTED...LEE OF LAKE ONTARIO

CONCERNING...HEAVY SNOW

VALID 061736Z - 062130Z

A SINGLE W-E LAKE EFFECT SNOW BAND IS EXPECTED TO DEVELOP OVER LAKE
ONTARIO DURING THE NEXT 2-4 HOURS...RESULTING IN INCREASING SNOWFALL
RATES ACROSS THE COUNTIES OF OSWEGO...SRN JEFFERSON AND SRN LEWIS BY
OR AFTER 21Z. GIVEN THE LIKELIHOOD OF A SINGLE BAND WITH STEEP
LOW-LEVEL LAPSE RATES...SNOWFALL RATES UP TO 2-3 INCH PER HOUR CAN
BE EXPECTED INTO THE EVENING.

SATELLITE IMAGERY SHOWS A CIRCULATION CENTER MOVING EWD ACROSS LAKE
ONTARIO AND WAS LOCATED OVER THE NORTH CENTRAL PORTION OF THE LAKE
AS OF 17Z. BACKED LOW-LEVEL SWLY WINDS WITH DIRECTIONAL SHEAR FROM
THE SURFACE TO 3 KM IN ADVANCE OF THIS FEATURE WILL CONTINUE TO
TEMPORARILY DISORGANIZE THE CURRENT BAND OF SNOW IN LEE OF LAKE
ONTARIO. MEANWHILE...AREA VADS INDICATE LOW-LEVEL WINDS VEERING TO
THE WEST WITH THE PASSAGE OF THE CIRCULATION CENTER AND SURFACE
TROUGH WHICH EXTENDED SSELY TO BETWEEN ITH AND BGM AT 17Z. BUF
RADAR SHOWS 1-3 NARROW BANDS DEVELOPING ATTM OVER LAKE ONTARIO ALONG
AND WEST OF THE CIRCULATION CENTER...WHICH IS EVIDENT OF THE
DEEPENING WLY WINDS.

RADAR/SATELLITE TRENDS INDICATE THE CIRCULATION CENTER WILL MOVE
EAST OF LAKE ONTARIO BY 20Z...WITH WLY LOWER TROPOSPHERIC WINDS
RESULTING IN THE DEVELOPMENT OF A SINGLE BAND BY MID-LATE AFTERNOON
ALONG THE LONG AXIS OF LAKE ONTARIO. ARCTIC AIR WILL SPREAD EWD
ACROSS THE WARM /4-5C/ ICE-FREE LAKE WATERS STEEPENING SFC-3 KM
LAPSE RATES TO NEAR 9 C/KM. THIS WILL ENHANCE THE CONVECTIVE NATURE
WITH HIGH SNOWFALL RATES. IN ADDITION...WLY WINDS WILL INCREASE TO
20-30 KT BY LATE THIS AFTERNOON... SUPPORTING WHITEOUT CONDITIONS.

..PETERS.. 01/06/2004

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

ATTN...WFO...BGM...BUF...

43907617 43927558 43807521 43497526 43337554 43357644
43597626



ACUS11 KWNS 061345
SWOMCD
SPC MCD 061344
WAZ000-ORZ000-061745-

MESOSCALE DISCUSSION 0012
NWS STORM PREDICTION CENTER NORMAN OK
0744 AM CST TUE JAN 06 2004

AREAS AFFECTED...NWRN OR THROUGH SWRN WA

CONCERNING...WINTER MIXED PRECIPITATION

VALID 061344Z - 061745Z

SNOW SHOULD GRADUALLY TRANSITION TO FREEZING RAIN FROM SW TO NE
ACROSS NWRN OR AND SWRN WA THROUGH THE MORNING. PERIODS OF MODERATE
TO HEAVY SNOW WILL LIKELY PERSIST OVER THE CASCADE RANGE.

THIS MORNING PRECIPITATION CONTINUES TO SPREAD INLAND ALONG WARM
CONVEYOR BELT DOWNSTREAM FROM UPPER TROUGH OVER THE ERN PACIFIC. AS
OF 13Z THE PRECIPITATION REMAINED MOSTLY IN THE FORM OF SNOW OVER
MUCH OF THE AREA. HOWEVER...SNOW WAS BEGINNING TO CHANGE TO FREEZING
RAIN FROM NEAR EUGENE NWWD THROUGH COASTAL OR. AS THE STRONG 50+ KT
SSWLY LOW LEVEL JET CONTINUES SHIFTING EWD NEXT SEVERAL HOURS...A
LAYER OF ABOVE FREEZING AIR WILL ADVECT OVER TOP OF THE VERY COLD
AND DENSE AIR NEAR THE SURFACE...RESULTING IN SNOW TRANSITIONING TO
FREEZING RAIN. THE FREEZING RAIN MAY PERSIST INTO THE AFTERNOON IN
THE WILLAMETTE VALLEY FROM SALEM NEWD THROUGH PORTLAND AND PORTIONS
OF SWRN WA WHERE THE LOW LEVEL COLD AIR WILL BE SLOWER TO ERODE.
FARTHER EAST...SNOW SHOULD CONTINUE TO INCREASE ALONG THE CASCADE
RANGE AS THE LOW LEVEL FLOW VEERS AND STRENGTHENS...ENHANCING
OROGRAPHIC LIFT.

..DIAL.. 01/06/2004

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

ATTN...WFO...PDT...SEW...PQR...

43892281 44242363 46262350 46922281 46932148 45682140
44362174



ACUS11 KWNS 060519
SWOMCD
SPC MCD 060519
WAZ000-ORZ000-060915-

MESOSCALE DISCUSSION 0011
NWS STORM PREDICTION CENTER NORMAN OK
1119 PM CST MON JAN 05 2004

AREAS AFFECTED...NWRN OREGON...WRN WASHINGTON

CONCERNING...WINTER MIXED PRECIPITATION

VALID 060519Z - 060915Z

...SNOW WILL INCREASE IN INTENSITY WEST OF THE CASCADE RANGE OVER
THE NEXT FEW HOURS. FREEZING RAIN WILL ALSO SPREAD NWD ACROSS THE
WILLAMETTE VALLEY...

BROAD WARM CONVEYOR BELT OF DEEPER PRECIPITATION IS SHIFTING EWD
WITH LEADING EDGE OF THIS ACTIVITY NOW SPREADING ONSHORE ACROSS
PORTIONS OF WRN ORE/WA. STRONG PRESSURE GRADIENT DUE TO POLAR HIGH
EAST OF THE CASCADES WILL CONTINUE TO FORCE COLD AIR INTO THE
WILLAMETTE VALLEY REGION BENEATH GRADUALLY WARMING MID LEVEL COLUMN.
ALTHOUGH MUCH OF THE INITIAL PRECIPITATION WILL BEGIN AS SNOW
ACROSS ORE...FORECAST SOUNDINGS STRONGLY SUGGEST SNOW WILL CHANGE TO
FREEZING RAIN AROUND 07Z FROM SOUTH...NEAR EUGENE...TO
NORTH...AROUND PORTLAND BY 12Z. ALL BUT EXTREME SWRN COASTAL AREAS
OF WA WILL MAINTAIN SNOW PROFILE THROUGH 12Z. SNOW RATES WILL
APPROACH 1 INCH PER HOUR IN THE VALLEYS WITH HEAVY ICING EXPECTED
ACROSS THE SRN WILLAMETTE VALLEY.

..DARROW.. 01/06/2004

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

ATTN...WFO...SEW...PQR...

48362262 47342190 45242197 43672279 44322402 46472399
48272459



ACUS11 KWNS 060519
SWOMCD
SPC MCD 060519
WAZ000-ORZ000-060915-

MESOSCALE DISCUSSION 0011
NWS STORM PREDICTION CPRECIPITATION

VALID 060519Z - 060915Z

...SNOW WILL INCREASE IN INTENSITY WEST OF THE CASCADE RANGE OVER
THE NEXT FEW HOURS. FREEZING RAIN WILL ALSO SPREAD NWD ACROSS THE
WILLAMETTE VALLEY...

BROAD WARM COASCADE RANGE OVER
THE NEXT FEW HOURS. FREEZING RAIN WILL ALSO SPREAD NWD ACROSS THE
WILLAMETTE VALLEY...

BROAD WARM CONVEYOR BELT OF DEEPER PRECIPITATION IS SHIFTING EWD
WITH LEADING EDGE OF THIS ACTIVITY NOW SPREADING ONSHORE ACROSS
PORTIONS OF WRN ORE/WA. STRONG PRESSURE GRADIENT DUE TO POLAR HIGH
EAST OF THE CASCADES WILL CONTINUE TO FORCE COLD AIR INTO THE
WILLAMETTE VALLEY REGION BENEATH GRADUALLY WARMING MID LEVEL COLUMN.
ALTHOUGH MUCH OF THE INITIAL PRECIPITATION WILL BEGIN AS SNOW
ACROSS ORE...FORECAST SOUNDINGS STRONGLY SUGGEST SNOW WILL CHANGE TO
FREEZING RAIN AROUND 07Z FROM SOUTH...NEAR EUGENE...TO
NORTH...AROUND PORTLAND BY 12Z. ALL BUT EXTREME SWRN COASTAL AREAS
OF WA WILL MAINTAIN SNOW PROFILE THROUGH 12Z. SNOW RATES WILL
APPROACH 1 INCH PER HOUR IN THE VALLEYS WITH HEAVY ICING EXPECTED
ACROSS THE SRN WILLAMETTE VALLEY.

..DARROW.. 01/06/2004

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

ATTN...WFO...SEW...PQR...

48362262 47342190 45242197 43672279 44322402 46472399
48272459