Alert archive / Idaho / Severe Thunderstorm Warnings in 2014

Severe Thunderstorm Warning 36, NWS Boise, ID

August 21, 20145 counties in Idaho

NWS Boise, ID issued this severe thunderstorm warning at Aug 21, 2014, 5:45 PM MDT for 5 counties in Idaho. It was in force for 45 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Aug 21, 2014, 5:45 PM MDT (23:45 UTC)
Expired
Aug 21, 2014, 6:30 PM MDT
In force
45 min
Issued by
NWS Boise, ID
Area
Storm-based polygon

Counties Camas County, ID, Elmore County, ID, Gooding County, ID, Jerome County, ID, Twin Falls County, ID

The radar

The Boise radar (KCBX), 130 km from the middle of the area, began a volume at 23:49 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, 11.8 hours before the alert went out and 131 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 2014-08-21Temperature 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 2014-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 44 square meters per square second.1939Sfc1 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
1570 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
44 m²/s²
0-3 km storm-relative helicity
110 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Boise, ID wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 21, 3:03 PM MDT, 2 hours 42 minutes earlier.

Area forecast discussion, Aug 21, 3:03 PM MDT, 2 hours 42 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
303 PM MDT THU AUG 21 2014

.SHORT TERM...TONIGHT THROUGH SATURDAY...ISOLATED THUNDERSTORMS
HAVE POPPED UP SOUTH AND EAST OF BOISE AND ARE MOVING EAST AT
10-20 MPH. THIS IS THE FAVORED LOCATION FOR THE REST OF THE
EVENING. A HAIL SPIKE WAS SEEN ON DUAL POL RADAR ON A STORM NEAR
HILL CITY. STORM TOPS ARE AROUND 35-40K FT MSL. STORMS ARE
EXPECTED TO BRING GUSTY WINDS AND SMALL HAIL. NEAR THE NV BORDER
WHERE HIGH PWAT AND SLOWER MOTIONS WERE NOTED BRIEF HEAVY RAIN IS
ALSO POSSIBLE. AFTER A LULL LATE FROM LATE EVENING TO EARLY FRIDAY
MORNING A WELL ORGANIZED PERIOD OF SHOWERS AND THUNDERSTORMS IS
EXPECTED FRIDAY. THIS IS DUE TO A DIGGING LONG WAVE TROUGH WITH
EXTRA ENERGY IN THE FORM OF A SHORTWAVE VORT WHICH LOOKS TO BE
OVER SE OREGON FRIDAY MORNING AND SW IDAHO FRIDAY AFTERNOON. THE
SHORT WAVE FEATURE WAS OBSERVED ON WATERVAPOR SATELLITE IMAGERY
NEAR 50N 130W THIS AFTERNOON. GFS/NAM ARE WITHIN 3 HRS TIMING THE
SYSTEM ACROSS SW IDAHO FRIDAY AFTERNOON. LATE FRIDAY AFTERNOON A
SURFACE LOW IS EXPECTED TO SHIFT E ACROSS THE ID-NV BORDER WHILE
ALOFT THE DIGGING UPPER LOW IS EXPECTED TO EXPAND OVER OREGON.
FRIDAY NIGHT AND SATURDAY THIS LOW WILL TRAVERSE SW IDAHO FOLLOWED
BY COOL NW FLOW AT THE SURFACE AND ALOFT BY SATURDAY
AFTERNOON...THROUGHOUT SE OREGON AND SW IDAHO. HIGH TEMPS STILL
EXPECTED TO PLUMMETT TO 10 DEGREES BELOW NORMAL BY SATURDAY. MAIN
CHANGE THIS PACKAGE WAS TO INCREASE QPF AND POP OVER CENTRAL IDAHO
18Z FRIDAY - 06Z SATURDAY.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY...COOL UPPER LEVEL
TROUGH WILL BE SLOW TO MOVE OUT OF THE FORECAST AREA AS IT IS
SANDWICHED IN BETWEEN TWO BLOCKING HIGHS...ONE OVER THE CENTRAL
UNITED STATES AND THE OTHER IN THE NORTHEAST PACIFIC OCEAN. THE
NORTHEAST PACIFIC RIDGE WILL START TO SHIFT INLAND BY TUESDAY
BRINGING WARMER TEMPERATURES AND DRIER CONDITIONS. THE LATEST
ECMWF MODEL RUN BUILDS THE RIDGE OFF THE WEST COAST JUST AS THE
GFS HAS FOR THE LAST FEW RUNS...INCREASING OUR FORECAST
CONFIDENCE. BY THURSDAY THE RIDGE BEGINS TO SHIFT EAST ALLOWING
THE FLOW TO SHIFT TO A MORE ZONAL REGIME. CHANCES OF PRECIPITATION
WILL STAY TO OUR HIGHER TERRAIN MOSTLY IN THE NORTHEAST.

&&

.AVIATION...VFR. ISOLATED SHOWERS AND THUNDERSTORMS MAINLY SOUTH AND
EAST OF KTWF THIS AFTERNOON AND IN CENTRAL IDAHO MOUNTAINS MAINLY
EAST OF KSNT. SURFACE WINDS GENERALLY WESTERLY 12KT OR LESS. WINDS
ALOFT AT 10K FEET MSL...SW 15-25KT.

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.

&&

WEATHER.GOV/BOISE

SHORT TERM...VM
LONG TERM....KA/AB
AVIATION.....KA

In the hours before

Local storm report, Aug 21, 4:14 PM MDT, 1 hour 31 minutes before
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Local storm report, Aug 21, 4:32 PM MDT, 1 hour 13 minutes before
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Local storm report, Aug 21, 4:47 PM MDT, 58 minutes before
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Local storm report, Aug 21, 4:56 PM MDT, 49 minutes before
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Special weather statement, Aug 21, 5:08 PM MDT, 37 minutes before
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Local storm report, Aug 21, 5:23 PM MDT, 22 minutes before
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      <h1 id="headline">This service is currently unavailable.</h1>
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        The site you requested is temporarily down for maintenance or an unexpected outage.
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      <p id="message2">
        Please try again in a few minutes.
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The office that day

Everything else NWS Boise, ID issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 21, 1:27 PM MDTSpecial Weather StatementBOIGooding48 min
Aug 21, 3:26 PM MDTSpecial Weather StatementBOIJerome, Twin Falls49 min
Aug 21, 3:54 PM MDTSpecial Weather StatementBOITwin Falls51 min
Aug 21, 4:05 PM MDTSevere Thunderstorm WarningBOIGooding, Jerome, Twin Falls55 min
Aug 21, 5:08 PM MDTSpecial Weather StatementBOIJerome52 min

Nearby

Severe Thunderstorm Warnings in Idaho, 2014Every severe thunderstorm warning in 2014

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.