Alert archive / California / Mesoscale Discussions in 2004

Mesoscale Discussion 1

January 1, 2004Shasta County, Siskiyou County, Trinity County, California; Jackson County, Josephine County, Oregon

The Storm Prediction Center issued this mesoscale discussion at Jan 1, 2004, 1:48 AM PST for Shasta County, Siskiyou County, Trinity County, California; Jackson County, Josephine County, Oregon. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jan 1, 2004, 1:48 AM PST (09:48 UTC)
Expired: Jan 1, 2004, 4:15 AM PST
In force: 2 hr
Issued by: the Storm Prediction Center

Counties Shasta County, CA, Siskiyou County, CA, Trinity County, CA, Jackson County, OR, Josephine County, OR

The radar

The Medford radar (KMAX), 92 km from the middle of the area, began a volume at 09:50 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Medford/Jackson, OR (KMFR), launched 00:00Z, 9.8 hours before the alert went out and 125 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 618 m above ground
0-6 km bulk shear: 73 kt
0-1 km storm-relative helicity: 205 m²/s²
0-3 km storm-relative helicity: 346 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

459 
ACUS11 KWNS 010948
SWOMCD
SPC MCD 010948 
CAZ000-ORZ000-011215-

MESOSCALE DISCUSSION 0001
NWS STORM PREDICTION CENTER NORMAN OK
0348 AM CST THU JAN 01 2004

AREAS AFFECTED...NRN CA/SWRN ORE

CONCERNING...PRECIPITATION TRENDS...HEAVY SNOW 

VALID 010948Z - 011215Z

SNOW RATES WILL INCREASE BY AROUND 12Z...TO LIKELY WELL IN EXCESS OF
2 INCHES PER HOUR AT HIGHER ELEVATIONS...PERSISTING THROUGH THE LATE
MORNING HOURS.

INTENSIFYING MID-LEVEL SHORT WAVE TROUGH CONTINUES TO APPROACH THE
NORTH CENTRAL PACIFIC COAST...ACCOMPANIED BY DEEPENING SURFACE LOW. 
RAPID PRESSURE FALLS HAVE ALREADY BECOME EVIDENT ALONG IMMEDIATE
COASTAL AREAS...NORTH OF EUREKA CA INTO AREAS NORTH OF BROOKINGS
ORE...WHERE ETA/AVN SUGGEST LOW WILL MIGRATE INLAND AROUND/SHORTLY
AFTER 12Z.  STRENGTHENING LOW-LEVEL CONVERGENCE/WARM ADVECTION AND
INCREASINGLY DIVERGENT UPPER FLOW FIELD WILL CONTRIBUTE TO DRAMATIC
INCREASE IN UPWARD VERTICAL MOTION THROUGH DEEP TROPOSPHERIC LAYER
ACROSS THE SHASTA/SISKIYOU REGION INTO THE SOUTHERN CASCADES AND
NORTHERN SIERRA NEVADA DURING THE 12-15Z TIME FRAME.  THIS WILL
INCLUDE LEVELS WITH TEMPERATURES FAVORABLE TO DENDRITIC ICE CRYSTAL
GROWTH...SUPPORTING INCREASING SNOW RATES.  LOW-LEVEL WARMING SOUTH/
EAST OF LOW MAY SUPPORT RISE OF SNOW LEVELS TO 4-5 THOUSAND FEET
ALONG NORTHERN CALIFORNIA COASTAL RANGES...AND 3-4 THOUSAND FEET
NORTH OF THE REDDING/RED BLUFF AREAS...WHILE IN AREAS NEAR NORTH
THROUGH EAST OF MEDFORD...SNOW LEVELS REMAIN AROUND 1000 TO 2000
FEET.

..KERR.. 01/01/2004

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

ATTN...WFO...REV...MFR...STO...EKA...

43002324 43302237 42442147 40932110 40302063 39752141
40402189 40592233 40482287 40062296 39752279 39622306
40502340 41212363 42102377 42472394 42682360

Nearby

Mesoscale Discussions in California, 2004 Mesoscale Discussions in Oregon, 2004 Every mesoscale discussion in 2004

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.