Alert archive / Idaho / Mesoscale Discussions in 2017
Mesoscale Discussion 463
The Storm Prediction Center issued this mesoscale discussion at Apr 7, 2017, 1:00 PM MDT for 4 states. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 7, 2017, 1:00 PM MDT (19:00 UTC)
- Expired
- Apr 7, 2017, 3:30 PM MDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 5%
All 26 counties
Adams County, ID, Benewah County, ID, Bonner County, ID, Boundary County, ID, Clearwater County, ID, Idaho County, ID, Kootenai County, ID, Latah County, ID, Lewis County, ID, Nez Perce County, ID, Shoshone County, ID, Washington County, ID, Mineral County, MT, Sanders County, MT, Baker County, OR, Umatilla County, OR, Union County, OR, Wallowa County, OR, Adams County, WA, Asotin County, WA, Columbia County, WA, Garfield County, WA, Pend Oreille County, WA, Spokane County, WA, Walla Walla County, WA, Whitman County, WA
The radar
The Pendleton radar (KPDT), 150 km from the middle of the area, began a volume at 19:01 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 12:00Z, 7.0 hours before the alert went out and 169 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 781 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km storm-relative helicity
- 323 m²/s²
- 0-3 km storm-relative helicity
- 516 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
661
ACUS11 KWNS 071900
SWOMCD
SPC MCD 071900
MTZ000-IDZ000-ORZ000-WAZ000-072130-
Mesoscale Discussion 0463
NWS Storm Prediction Center Norman OK
0200 PM CDT Fri Apr 07 2017
Areas affected...Portions of northeastern OR...eastern WA...northern
ID...and far northwestern MT
Concerning...Severe potential...Watch unlikely
Valid 071900Z - 072130Z
Probability of Watch Issuance...5 percent
SUMMARY...Isolated strong to locally damaging wind gusts and perhaps
some hail will be possible with developing thunderstorms through the
afternoon/early evening. Due to the marginal nature of the severe
threat, watch issuance is not expected.
DISCUSSION...Beneath a strong, cyclonically curved mid/upper-level
jet, cumulus clouds have become more agitated over the past hour
across the northern Intermountain region per recent visible
satellite imagery. Behind morning convection, some breaks in the
cloud cover have allowed surface temperatures to generally warm into
the 50s and lower 60s outside of high terrain. Although low-level
moisture remains quite limited, with precipitable water values
around 0.5 inch or less, there appears to be sufficient instability
(MUCAPE up to 500 J/kg) to support convective development this
afternoon and early evening. Steep low and mid-level lapse rates per
RAP forecast soundings will encourage efficient downward momentum
transfer in convective downdrafts, and strong to locally damaging
winds may occur with any thunderstorm. In addition, 35-40 kt of
effective bulk shear should support updraft organization within the
strongest cores, and isolated hail approaching severe levels may not
be out of the question. Overall, the severe threat is expected to
remain isolated and marginal given weak instability, and the
likelihood of watch issuance is low. Regardless, convective trends
will be monitored through the afternoon and early evening.
..Gleason/Weiss.. 04/07/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MSO...BOI...OTX...PDT...
LAT...LON 47931822 48931740 48771590 48031504 46931481 45791523
44671620 43931692 43841769 44051860 44671894 45851894
47931822Nearby
Mesoscale Discussions in Idaho, 2017Mesoscale Discussions in Washington, 2017Mesoscale Discussions in Oregon, 2017Every mesoscale discussion in 2017
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.