Alert archive / Washington / Mesoscale Discussions in 2012

Mesoscale Discussion 1463

July 13, 20124 counties in Idaho; 7 counties in Washington

The Storm Prediction Center issued this mesoscale discussion at Jul 13, 2012, 9:49 PM PDT for 4 counties in Idaho; 7 counties in Washington. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued
Jul 13, 2012, 9:49 PM PDT (04:49 UTC)
Expired
Jul 13, 2012, 10:45 PM PDT
In force
56 min
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Benewah County, ID, Bonner County, ID, Boundary County, ID, Kootenai County, ID, Adams County, WA, Ferry County, WA, Lincoln County, WA, Pend Oreille County, WA, Spokane County, WA, Stevens County, WA, Whitman County, WA

The radar

The Spokane radar (KOTX), 40 km from the middle of the area, began a volume at 04:51 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

Spokane, WA (KOTX), launched 00:00Z, 4.8 hours before the alert went out and 88 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, Spokane, WA at 00:00Z on 2012-07-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 799 joules per kilogram.LCLLFCEL10008507005003002001001 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, Spokane, WA at 00:00Z on 2012-07-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -17 square meters per square second.19395878Sfc1 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
799 J/kg
Mixed-layer CIN
-103 J/kg
Mixed-layer LCL
2367 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
-17 m²/s²
0-3 km storm-relative helicity
84 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.

011 
ACUS11 KWNS 140450
SWOMCD
SPC MCD 140449
IDZ000-WAZ000-140545-

MESOSCALE DISCUSSION 1463
NWS STORM PREDICTION CENTER NORMAN OK
1149 PM CDT FRI JUL 13 2012

AREAS AFFECTED...ERN WA AND NRN ID PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 140449Z - 140545Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...POTENTIAL EXISTS FOR TSTMS TO INCREASE IN COVERAGE LATE
THIS EVENING INTO THE EARLY OVERNIGHT ACROSS ERN WA AND THE NRN ID
PANHANDLE...WITH AN ISOLATED THREAT FOR STRONG TO SEVERE STORMS.

DISCUSSION...TRENDS IN EVENING WATER VAPOR IMAGERY SHOWED A
QUASI-STATIONARY UPPER LOW OVER WRN WA...WITH A PLUME OF MOISTURE
CONTINUING TO SPREAD NWD FROM THE GREAT BASIN INTO THE NRN
INTERMOUNTAIN REGION.  AN APPARENT EMBEDDED MIDLEVEL IMPULSE ALONG
THE WRN PERIPHERY OF THIS MOISTURE PLUME WAS TRACKING NWD THROUGH
NERN ORE/SERN WA BETWEEN 01-04Z.  ASCENT WITH THIS FEATURE IS LIKELY
AIDING IN THE ONGOING TSTM ACTIVITY OVER NERN ORE/SERN WA.  RADAR
IMAGERY ALSO SHOWED STORMS DEVELOPING OVER THE FAR NRN ID PANHANDLE.

THE LAST SEVERAL RUNS OF THE HRRR SUGGESTED STORMS WILL INCREASE IN
COVERAGE BETWEEN 05-09Z AS ONGOING ACTIVITY IN NERN ORE/SERN WA AND
THE ATTENDANT MIDLEVEL IMPULSE SPREAD NWD INTO NERN WA AND THE NRN
ID PANHANDLE WHERE OBJECTIVE ANALYSES INDICATED STRONGER
INSTABILITY.  MIDLEVEL LAPSE RATES OF 7-7.5 C/KM AND THE AVAILABLE
INSTABILITY ARE SUPPORTIVE OF SOME HAIL AND STRONGER WIND GUSTS...
BUT WEAK DEEP LAYER SHEAR SHOULD LIMIT STORM ORGANIZATION/
SUSTENANCE...THUS WATCH ISSUANCE DOES NOT APPEAR NECESSARY AT THIS
TIME.

..PETERS/THOMPSON.. 07/14/2012

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

ATTN...WFO...OTX...

LAT...LON   48991664 48911618 48061623 46721684 46721790 47061865
            47841898 48921918 48991664

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 14, 12:57 PM PDTMesoscale DiscussionSPCAda, Adams, Boise, Canyon, Gem, Payette and 2 more93 min
Jul 14, 1:27 PM PDTSevere Thunderstorm WatchSPCAda, Adams, Blaine, Boise, Butte, Camas and 14 more9 hr

Nearby

Mesoscale Discussions in Washington, 2012Mesoscale 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.