Alert archive / Wyoming / Mesoscale Discussions in 2003

Mesoscale Discussion 261

March 17, 20036 counties in Wyoming

The Storm Prediction Center issued this mesoscale discussion at Mar 17, 2003, 10:38 AM MST for 6 counties in Wyoming. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Mar 17, 2003, 10:38 AM MST (17:38 UTC)
Expired: Mar 17, 2003, 5:15 PM MST
In force: 7 hr
Issued by: the Storm Prediction Center

Counties Albany County, WY, Campbell County, WY, Carbon County, WY, Converse County, WY, Johnson County, WY, Natrona County, WY

The radar

The Riverton/Lander radar (KRIW), 185 km from the middle of the area, began a volume at 17:42 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

Riverton, WY (KRIW), launched 12:00Z, 5.6 hours before the alert went out and 179 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: 594 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 24 m²/s²
0-3 km storm-relative helicity: 179 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.

218 
ACUS11 KWNS 171738
SWOMCD
SPC MCD 171738 
WYZ000-COZ000-MTZ000-180015-

MESOSCALE DISCUSSION 0261
NWS STORM PREDICTION CENTER NORMAN OK
1138 AM CST MON MAR 17 2003

AREAS AFFECTED...CNTRL / ECNTRL WY

CONCERNING...HEAVY SNOW 

VALID 171738Z - 180015Z

MULTIPLE DAY HEAVY SNOWFALL EVENT TO BEGIN IN ERN/CNTRL WY OVER
THE NEXT FEW HOURS. SNOWFALL RATES WILL INCREASE TO AT LEAST 1
IN/HR BY 17/21-18/00Z.



WV/IR IMAGERY SHOW MID LVL CYCLONE OVER CNTRL UT WITH DISCERNABLE
CYCLONIC FLOW WNWWD INTO DISCUSSION AREA. RECENT COOLING CLOUD
TOPS ON IR IMAGERY IN SERN WY INDICATIVE OF AMOUNT OF INSTABILITY
AS A RESULT OF INCREASING LOW-LVL UPSLOPE FLOW / UPPER LVL
DIFLUENCE IN THE REGION. 17/12Z SOUNDING FROM NORTH PLATTE
REVEALS 700-500MB LAPSE RATES AROUND 8 C/KM WITH NEARLY 500 J/KG
OF ELEVATED INSTABILITY WHILE THE MRNG SOUNDING AT RIVERTON
REVEALS A SATURATED PROFILE WITH A SFC TEMPERATURE NEAR FREEZING.



THE CNTRL UT MID-LVL LOW IS EXPECTED TO WEAKEN DURING THE
DAY...AND THEN REDEVELOP COINCIDENT WITH THE STRENGTHENING SFC
LOW IN SERN CO. AS THIS OCCURS...BOTH UPPER LVL DIFLUENCE AND 850
MB UPSLOPE FLOW /25-35 KTS/ ARE EXPECTED TO INCREASE AIDING UVM
IN THE DISCUSSION AREA. ETA FCST SOUNDINGS INDICATE FAVORED
DENDRITIC GROWTH ZONE FOR HVY SNOW WILL BECOME MORE OPTIMAL
BETWEEN 18Z-21Z THIS AFTERNOON IN ECNTRL WY...INITIATING A RATHER
LONG-LIVED HVY SNOWFALL EVENT.

..NADEN.. 03/17/2003

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

ATTN...WFO...UNR...BOU...CYS...BYZ...RIW...

40910571 41020522 41210489 41550464 41790496 42510539
43960536 44570542 45030632 44630687 44330707 43840734
43120839 42910885 42180807 41430734 41050655 41080621

Nearby

Mesoscale Discussions in Wyoming, 2003 Every mesoscale discussion in 2003

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.