Alert archive / Utah / Mesoscale Discussions in 2008

Mesoscale Discussion 2521

December 25, 20084 counties in Nevada; 7 counties in Utah

The Storm Prediction Center issued this mesoscale discussion at Dec 25, 2008, 8:42 AM PST for 4 counties in Nevada; 7 counties in Utah. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Dec 25, 2008, 8:42 AM PST (16:42 UTC)
Expired
Dec 25, 2008, 12:45 PM PST
In force
4 hr
Issued by
the Storm Prediction Center

Counties Elko County, NV, Eureka County, NV, Lander County, NV, White Pine County, NV, Davis County, UT, Juab County, UT, Morgan County, UT, Salt Lake County, UT, Tooele County, UT, Utah County, UT, Weber County, UT

The radar

The Elko radar (KLRX), 167 km from the middle of the area, began a volume at 16:48 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

Elko, NV (KLKN), launched 12:00Z, 4.7 hours before the alert went out and 96 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-pSkew-T log-p diagram, Elko, NV at 12:00Z on 2008-12-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Elko, NV at 12:00Z on 2008-12-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 237 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
893 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
237 m²/s²
0-3 km storm-relative helicity
340 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.

000 
ACUS11 KWNS 251642
SWOMCD
SPC MCD 251642 
UTZ000-NVZ000-252045-

MESOSCALE DISCUSSION 2521
NWS STORM PREDICTION CENTER NORMAN OK
1042 AM CST THU DEC 25 2008

AREAS AFFECTED...NRN NV/NRN UT

CONCERNING...HEAVY SNOW 

VALID 251642Z - 252045Z

HOURLY SNOWFALL RATES OF 1-3 ARE LIKELY THROUGH THE AFTN ACROSS
PORTIONS OF NRN NV/UT.  RATES WILL BEGIN TO DECREASE ACROSS NRN NV
LATER THIS AFTN.

A BROAD WARM CONVEYOR BELT...ENHANCED BY A LEAD SHORTWAVE TROUGH
OVER NRN UT/ID...HAS BEEN RESPONSIBLE FOR MODEST SNOWFALL EARLY THIS
MORNING OVER NRN UT/NV.  PCPN RATES WILL LIKELY INCREASE THROUGH THE
AFTN...HOWEVER...AS THE NOSE OF A 70 KT MID-LVL JET /OBSERVED AT
KRNO/ SPREADS ACROSS THE REGION.  THIS WAS ALREADY LIKELY ENHANCING
SNOWFALL ALONG A SEWD MOVING CDFNT OVER NCNTRL NV.  THIS HEAVY
SNOWBAND WILL GRADUALLY SPREAD SEWD WITH TIME THIS AFTN/EVE.
CROSS-SECTIONS DEPICT DECREASING STATIC STABILITY ALOFT THROUGH THE
AFTN...PARTICULARLY OVER CNTRL/NRN NV...WHERE CONVECTION WILL
FURTHER ENHANCE PCPN RATES.

STRONG SLY FLOW AHEAD OF THE FRONT WILL CAUSE A SLIGHT RISE IN SNOW
LEVELS TO ALMOST 5000 FEET THIS AFTN ACROSS NERN NV/NRN UT WITH LWR
VLYS MIXING/CHANGING TO RAIN.  BUT...HEAVIER SNOW RATES WILL LOWER
LEVELS SOMEWHAT SO THAT EVEN THE HIGHER VLYS MAY EXPERIENCE
PREDOMINATELY WET SNOW.  HIGHEST SNOWFALL RATES/TOTALS WILL OCCUR
ACROSS THE HIGHER RUBY/SNAKE MOUNTAINS IN NV AND ACROSS THE NRN
WASATCH MOUNTAINS IN NRN UT.  SNOW WILL BEGIN TO DECREASE WITH
FRONTAL PASSAGE ACROSS NRN NV BY EVENING...BUT CONTINUE ACROSS
PORTIONS OF THE NRN WASATCH MOUNTAINS...ESPECIALLY AS LAKE EFFECT
SNOW BEGINS TO EVOLVE.

..RACY.. 12/25/2008

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

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
SCHEDULED BASIS FROM DECEMBER 1 THROUGH FEBRUARY 28...FOUR
TIMES A DAY...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.

ATTN...WFO...SLC...LKN...REV...

LAT...LON   39491766 41731623 41501133 38931188 39491766

Nearby

Mesoscale Discussions in Utah, 2008Mesoscale Discussions in Nevada, 2008Every mesoscale discussion in 2008

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.