Alert archive / Oregon / Mesoscale Discussions in 2012

Mesoscale Discussion 1506

July 19, 201215 counties in Oregon; 7 counties in Washington

The Storm Prediction Center issued this mesoscale discussion at Jul 19, 2012, 4:11 PM PDT for 15 counties in Oregon; 7 counties in Washington. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: Jul 19, 2012, 4:11 PM PDT (23:11 UTC)
Expired: Jul 19, 2012, 5:45 PM PDT
In force: 94 min
Issued by: the Storm Prediction Center

All 22 counties

Clackamas County, OR, Gilliam County, OR, Hood River County, OR, Jefferson County, OR, Lane County, OR, Linn County, OR, Marion County, OR, Morrow County, OR, Multnomah County, OR, Sherman County, OR, Umatilla County, OR, Union County, OR, Wallowa County, OR, Wasco County, OR, Wheeler County, OR, Asotin County, WA, Benton County, WA, Columbia County, WA, Franklin County, WA, Klickitat County, WA, Skamania County, WA, Walla Walla County, WA

The radar

The Pendleton radar (KPDT), 76 km from the middle of the area, began a volume at 23:13 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

Salem/Mcnary, OR (KSLE), launched 12:00Z, 11.2 hours before the alert went out and 266 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: 670 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 16 m²/s²
0-3 km storm-relative helicity: 49 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.

018 
ACUS11 KWNS 192311
SWOMCD
SPC MCD 192311 
IDZ000-ORZ000-WAZ000-200045-

MESOSCALE DISCUSSION 1506
NWS STORM PREDICTION CENTER NORMAN OK
0611 PM CDT THU JUL 19 2012

AREAS AFFECTED...OR...WA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 192311Z - 200045Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THE CHANCE FOR AT LEAST ISOLATED STRONG TO SEVERE STORMS
WAS LIKELY INCREASING ACROSS PORTIONS OF NRN/WRN ORE AND SRN WA
THROUGH THE EVENING HOURS. WHILE A WATCH MAY BE NEEDED...CURRENT
UNCERTAINTY REGARDING OVERALL SEVERE STORM COVERAGE SUGGESTS THAT
ISSUANCE IS NOT IMMINENT. CONDITIONS WILL CONTINUE TO BE MONITORED.

DISCUSSION...MODEST BOUNDARY LAYER DESTABILIZATION HAS OCCURRED
WITHIN A REGION WHERE STRONG DAYTIME HEATING HAS ACTED ON RELATIVELY
GREATER LOW LEVEL MOISTURE FROM THE WILLAMETTE VALLEY NORTH AND EAST
ACROSS THE COLUMBIA RIVER GORGE AND OVER THE COLUMBIA BASIN. WITH
SOME AREAS NOW ACHIEVING CONVECTIVE TEMPERATURES AROUND
90F...ISOLATED ROBUST TSTMS HAVE DEVELOPED...ESPECIALLY ACROSS NERN
ORE. ENTIRE AREA WILL REMAIN UNDER THE INFLUENCE OF A PRONOUNCED
MID/UPPER LOW OFF THE COAST THAT WILL LIKELY BEGIN TO ADVANCE ENEWD
LATER TONIGHT. MODEST DEEP-LAYER SLY FLOW IN THE ERN FLANK OF THE
UPPER LOW WAS RESULTING IN EFFECTIVE SHEAR MAGNITUDES SUPPORTIVE OF
UPDRAFT PERSISTENCE AND ROTATION. IN ADDITION TO HAIL...ANY STRONGER
CONVECTION SPREADING ACROSS THE RELATIVELY DEEPLY MIXED BOUNDARY
LAYER COULD PRODUCE STRONG TO DAMAGING WINDS.

DESPITE GENERALLY FAVORABLE CONDITIONS FOR SEVERE WEATHER...STORM
COVERAGE REMAINS SOMEWHAT IN DOUBT. IF GREATER DEVELOPMENT ENSUES IN
THE NEXT 1-2 HOURS...A WATCH MAY BE NEEDED ACROSS SOME OF THE
REGION.

..CARBIN.. 07/19/2012

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

ATTN...WFO...BOI...OTX...PDT...MFR...PQR...

LAT...LON   45001836 44452018 43962139 43392197 43702318 44452320
            45472272 46052212 46442063 46561944 46641865 46611814
            46391750 46051700 45551677 44951682 44811737 45001836

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 18, 5:23 PM PDT	Mesoscale Discussion	SPC	Union, Wallowa	67 min

Nearby

Mesoscale Discussions in Oregon, 2012 Mesoscale Discussions in Washington, 2012 Every 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.