Alert archive / Idaho / Mesoscale Discussions in 2012

Mesoscale Discussion 29

January 18, 20129 counties in Idaho

The Storm Prediction Center issued this mesoscale discussion at Jan 18, 2012, 5:40 AM MST for 9 counties in Idaho. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Jan 18, 2012, 5:40 AM MST (12:40 UTC)
Expired
Jan 18, 2012, 8:15 AM MST
In force
3 hr
Issued by
the Storm Prediction Center

Counties Ada County, ID, Boise County, ID, Camas County, ID, Elmore County, ID, Gem County, ID, Gooding County, ID, Jerome County, ID, Lincoln County, ID, Payette County, ID

The radar

The Boise radar (KCBX), 71 km from the middle of the area, began a volume at 12:42 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

Boise Airport, ID (KBOI), launched 12:00Z, 0.7 hours before the alert went out and 63 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, Boise Airport, ID at 12:00Z on 2012-01-18Temperature 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 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Boise Airport, ID at 12:00Z on 2012-01-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 251 square meters per square second.1939587897117136156Sfc1 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
1894 m above ground
0-6 km bulk shear
112 kt
0-1 km storm-relative helicity
251 m²/s²
0-3 km storm-relative helicity
308 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.

635 
ACUS11 KWNS 181241
SWOMCD
SPC MCD 181240
IDZ000-181515-

MESOSCALE DISCUSSION 0029
NWS STORM PREDICTION CENTER NORMAN OK
0640 AM CST WED JAN 18 2012

AREAS AFFECTED...PARTS OF THE SNAKE RIVER VALLEY INTO THE SAWTOOTH
MOUNTAINS...INCLUDING THE BOISE AREA

CONCERNING...HEAVY SNOW

VALID 181240Z - 181515Z

HEAVY SNOW RATES OF 1 TO 2+ INCHES PER HOUR ARE EXPECTED TO DEVELOP
ACROSS THE REGION THROUGH 15-18Z.

THE REMNANTS OF A DEEP MIXED BOUNDARY LAYER ARE STILL EVIDENT IN THE
12Z BOISE SOUNDING...BUT THIS APPEARS LIKELY TO BE OVERCOME DURING
THE 15-18Z TIME FRAME...IF NOT BEFORE...AS A STRONG LOWER/MID
TROPOSPHERIC JET STREAK CONTINUES NOSING INLAND ACROSS OREGON INTO
THE NORTHERN INTERMOUNTAIN REGION.  MOISTENING...AND STRENGTHENING
DEEP LAYER LIFT ASSOCIATED WITH WARM ADVECTION... SHOULD CONTRIBUTE
TO INCREASING PRECIPITATION RATES...WHICH WILL COOL/SATURATE THE
LOW-LEVEL ENVIRONMENT ACROSS THE SNAKE RIVER VALLEY IN AND AROUND
BOISE.  AS PRECIPITABLE WATER INCREASES IN EXCESS OF .5 INCHES...
AND LIFT INTENSIFIES WITHIN THE DENDRITIC GROWTH LAYER...SNOW RATES
IN EXCESS OF 1 INCH PER HOUR ARE PROBABLE...WITH RATES PERHAPS IN
EXCESS OF 2 INCHES PER HOUR IN THE MOUNTAINS NORTH AND EAST OF
BOISE.

..KERR.. 01/18/2012

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

ATTN...WFO...PIH...BOI...

LAT...LON   44691624 44701588 44301479 43751402 42591417 42381497
            43461650 44121684 44691624

Nearby

Mesoscale Discussions in Idaho, 2012Every mesoscale discussion in 2012

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.