Round Three of Potentially Damaging Tornados

The Storm Prediction Center in Norman OK is forecasting another round of severe thunderstorms including the potential of damaging tornados for Tuesday in the Gulf States.

Severe Thunderstorm Outlook for Tuesday April 29 2014

It has already been two deadly days  in much of the same area.  Following are the storm reports for those days so far.  The number of tornadoes will likely change some as surveys are conducted.

Severe Thunderstorms including Tornados Central U.S.

The Storm Prediction Center is expecting an active Severe Thunderstorm Sunday

 PUBLIC SEVERE WEATHER OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1232 PM CDT SUN APR 27 2014

   ...Severe thunderstorms expected over parts of the Ozarks later
   today and tonight...

   * LOCATIONS...
     Much of Arkansas
     Southern Missouri
     Extreme eastern Oklahoma
     Extreme northeast Texas

   * HAZARDS...
     Several tornadoes, a few intense
     Widespread large hail, some baseball size
     Scattered damaging winds

   * SUMMARY...
     Severe thunderstorms will affect Arkansas and adjacent areas of
     southern Missouri, eastern Oklahoma, and extreme northeast Texas
     this afternoon into tonight. The greatest tornado risk will be
     centered on Arkansas, where a few strong and long-track
     tornadoes will be possible through tonight. Otherwise, a band of
     severe thunderstorms will move across Missouri and Iowa this
     afternoon with damaging winds, large hail, and a few tornadoes.
     More isolated severe storms will be possible this afternoon
     across central Nebraska.

   Preparedness actions...

   Review your severe weather safety procedures for the possibility
   of dangerous weather today. Stay tuned to NOAA Weather Radio, 
   weather.gov, or other media for watches and warnings. A tornado
   watch means that conditions are favorable for tornadoes to form
   during the next several hours. If a tornado warning is issued for
   your area, move to a place of safety, ideally in a basement or
   interior room on the lowest floor of a sturdy building.

   &&

   ..Thompson.. 04/27/2014

Dangerous Severe Thunderstorms Possible This Weekend in the Central U.S.

Potentially dangerous severe thunderstorms are forecast for parts of the Central U.S. this coming weekend.  Tornadoes are likely along with large hail and damaging winds.  While still too early to pinpoint the area with the greatest threat the Storm Prediction Center has raised awareness in their 4-8 day outlook issued today.

 
   DAY 4-8 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0351 AM CDT WED APR 23 2014

   VALID 261200Z - 011200Z

   ...DISCUSSION...
   ..SIGNIFICANT MULTI-DAY SEVERE EVENT EXPECTED ACROSS PORTIONS OF THE
   CENTRAL AND SOUTHERN PLAINS SATURDAY AND SUNDAY AND ACROSS THE MS
   VALLEY AND MID SOUTH ON MONDAY...STRONG TORNADOES ARE POSSIBLE...

   MEDIUM RANGE FORECAST CONTINUES TO BE HEAVILY WEIGHTED TOWARD THE
   ECMWF DUE TO RUN-TO-RUN CONSISTENCY REGARDING THE 500MB EVOLUTION OF
   WRN U.S. TROUGH.  CONCERNS REGARDING POLAR FRONT UNDERCUTTING STRONG
   SWLY FLOW ALOFT HAVE ABATED THIS MORNING.  LATEST GUIDANCE DEEPENS
   LEE CYCLONE OVER SERN CO SATURDAY AFTERNOON WITH SUBSEQUENT MOVEMENT
   INTO WRN KS ON SUNDAY.  INTENSE 500MB SPEED MAX APPROACHING 90KT
   SHOULD ROUND THE BASE OF THE TROUGH ALONG THE AZ/MEXICAN BORDER THEN
   EJECT INTO SWRN KS EARLY SUNDAY.  AS A RESULT SFC LOW IS NOT
   EXPECTED TO ADVANCE APPRECIABLY EWD UNTIL LATER MONDAY AS SECONDARY
   MID-LEVEL SPEED MAX DEVELOPS FROM NORTH TX INTO THE LOWER OH RIVER
   VALLEY.

   MODERATE TO EXTREME INSTABILITY SHOULD DEVELOP EAST OF THE DRYLINE
   SATURDAY AFTERNOON ALONG ERN PLUME OF STEEP LAPSE RATES.  STRONGLY
   DIFLUENT FLOW ALOFT SHOULD ENCOURAGE VIGOROUS SUPERCELL DEVELOPMENT
   FROM PORTIONS OF WCNTRL TX...NWD INTO KS.  VERY LARGE HAIL AND
   TORNADOES CAN BE EXPECTED WITH THIS ACTIVITY.

   IT/S NOT ENTIRELY CLEAR HOW FAR EAST THE DRYLINE WILL MIX SUNDAY AS
   LOWEST PRESSURES WILL REMAIN FOCUSED ACROSS THE HIGH PLAINS OF WRN
   KS.  MODELS MIX DRYLINE EAST OF I-35 CORRIDOR ACROSS OK BY 18Z
   SUNDAY BUT THE DAY5 FORECAST WILL ACCOUNT FOR DRYLINE NOT MIXING
   ACROSS THE PLAINS AS FAST AS MODELS CURRENTLY DEPICT.  AS A
   RESULT...SUBSTANTIAL MID-LEVEL FLOW SHOULD OVERSPREAD THE
   MOIST/BUOYANT WARM SECTOR AND ANOTHER DIURNALLY-INITIATED ROUND OF
   POTENTIALLY TORNADIC SUPERCELLS COULD EVOLVE.

   LATER MONDAY IT APPEARS THE SFC FRONT/DRYLINE SHOULD ADVANCE INTO
   THE MS VALLEY.  SCATTERED-NUMEROUS SUPERCELLS SHOULD EVOLVE AHEAD OF
   THE FRONT FROM LA...NWD INTO MO AND POSSIBLY AS FAR EAST AS MIDDLE
   TN.  TORNADOES AND LARGE HAIL REMAIN POSSIBLE WITH WARM-SECTOR
   CONVECTION.

   ..DARROW.. 04/23/2014

Severe Thunderstorm Watch for Lincoln County including Star Valley

SEL6 URGENT - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WATCH NUMBER 86 NWS STORM PREDICTION CENTER NORMAN OK 230 PM MDT TUE APR 22 2014 THE NWS STORM PREDICTION CENTER HAS ISSUED A * SEVERE THUNDERSTORM WATCH FOR PORTIONS OF EASTERN IDAHO SOUTHWEST MONTANA WESTERN WYOMING * EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 230 PM UNTIL 1000 PM MDT. * PRIMARY THREATS INCLUDE... SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65 STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES SOUTHEAST OF MALAD CITY IDAHO TO 40 MILES WEST NORTHWEST OF HARLOWTON MONTANA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU6). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES. && DISCUSSION...TSTMS EXPECTED TO INCREASE IN COVERAGE/STRENGTH THROUGH EARLY TNGT ALONG AND AHEAD OF INTENSIFYING COLD FRONT CROSSING THE NRN GRT BASIN/NRN RCKYS...WITH DEVELOPMENT AIDED BY UPR IMPULSE APPROACHING FROM NV. STRENGTH OF LARGELY UNIDIRECTIONAL SSWLY WIND FIELD AND RELATIVELY STEEP LOW TO MID-LVL LAPSE RATES SUGGEST POTENTIAL FOR DOWNWARD MOMENTUM TRANSFER AND POSSIBLY DMGG SFC WIND GUSTS DESPITE SPARSE MOISTURE. AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 400. MEAN STORM MOTION VECTOR 21040. ...CORFIDI

Wind damage already reported in Southeast Idaho

Local Storm Report

04/22/2014 0225 PM

4 miles SSE of Rigby, Bonneville County.

Thunderstorm wind damage, reported by trained spotter.

Trailer house on Bonneville/Jefferson County line--145n between 3900 and 4000 east, has lost its roof. 6 to 8 inch tree limbs have fallen.

Strong, Potentially Damaging WInds Across Western Wyoming Today

A strong spring cold front will impact Star Valley and surrounding regions today.  To highlight the concern, the Storm Prediction Center in Norman OK has placed  parts of Southeast Idaho and far west Wyoming under a Slight Risk of severe  thunderstorms for later this afternoon and evening as the cold front passes.

The primary concern will be the potential for damaging surface winds as thunderstorms develop along and just ahead of the cold front.  The following graphic reflects this:

The morning 500 mb analysis clearly shows the deep trough of low pressure responsible for this concern moving inland from the west coast.

500 mb analysis 6am April 22 2014

The water vapor imagery  indicates the greatest energy with the trough as of 9 am this morning was moving across Northern California headed for Western Wyoming by this evening.

Water Vapor Imagery 9am April 22 2014

Winds will increase through the afternoon as temperatures rise into the 60s.  Thunderstorms will develop across the upper Snake River Valley by mid afternoon and move across Star Valley between 5-7pm.  Wind gusts to 50-60 mph will be possible at that time along with potential for small hail and rapidly falling temperatures.

Following is a model forecast of where the the strongest winds will be occurring around 6pm.

model forecast of winds in kt at 6pm April 22 2014.

Interesting to note that the strongest winds to near 55 kt are in southeastern Lincoln County, with much of Lincoln county southwest into the Salt Lake City region in the 40-50 kt range  However the risk of thunderstorms, which will enhance the otherwise expected strong winds, will be across far west Wyoming into southeast Idaho as reflected in the Slight Risk area.

Potential for damaging winds with or without the occurrence of thunderstorms will cover a wide area of western Wyoming later this afternoon and evening

Much colder with snow levels dropping down to the valley floors will occur later this evening, however snow amounts are not now expected to be more than an inch of two.  In the higher elevations, including Yellowstone NP, there is the potential for 4 or more inches as shown in the graphic below by Wednesday morning.

Probability of 4 or more inches of snow from 6am Tuesday to 6am Wednesday April 23 2014.

Water Year as of March 31 2014 for Western Wyoming-Star Valley

Percent of Normal Precipitation Oct 2013-March 2014

Temperature Departure from Normal Oct 2013-March 2014

It has been a very moist period since actually last September across much of Wyoming.  For comparison purposes will compare Star Valley measurements since last October 1st when the current water year began.

Following are the totals from COCoRAHS observers  in Star Valley.

Star Valley Ranch had 19.65 inches which included 172.5 inches of snow.

1.5 miles southeast of Thayne  had 15.19  inches  which included approximately 155 inches of snow.

5 miles southeast of Smoot had 16.70 inches which included 185 inches of snow

Another location on Star Valley Ranch measured 17.12 inches but did not have a snow total.

For comparison purposes the Willow Creek SNOTEL as of March 31 had reported 40.2 inches of precipitation since October 1 2013 along with a snow depth of 107 inches.

Following is a detailed summary of the water year across much of western Wyoming.  

2013-2014 Water Year Precipitation and Percent of Normal for Selected Stations
Wyoming Temperature and Precipitation Maps & Rankings Previous Annual and Water Year Summaries (2011-2014) More Historical Climate Data from Utah State
Station Name: Airports								Drought Conditions					Oct 2013	Nov 2013	Dec 2013		Jan 2014	Feb 2014	Mar 2014	Apr 2014	May 2014	Jun 2014	Jul 2014	Aug 2014	Sep 2014		Total for Water Year
click on location											D0	D1
for graph								D2		D3		D4
Big Piney								None					0.39	0.29	0.19		0.02	0.02	0.12								1.03
1981-2010 Normals													0.53	0.21	0.30		0.31	0.35	0.44	0.53	0.84	0.79	0.71	0.69	0.78		2.14
Percent of Normal													74	138	63		6	6	27								48
Buffalo								None					2.25	0.12	0.24		0.21	0.15	0.61								3.58
1981-2010 Normals													0.93	0.54	0.40		0.42	0.35	0.92	1.30	2.53	2.28	1.66	0.81	1.31		3.56
Percent of Normal													242	22	60		50	43	66								101
Casper								None					3.03	0.24	1.20		0.74	0.74	1.64								7.59
1981-2010 Normals													1.11	0.76	0.49		0.51	0.57	0.82	1.29	2.02	1.61	1.41	0.85	1.08		4.26
Percent of Normal													273	32	245		145	130	200								178
Snowfall													16.4	3.6	15.7		14.2	11.5	18.7								80.1
1981-2010 Normals													7.4	10.3	11.0		9.1	9.8	10.9	11.6	2.9	0.1	0.0	0.0	1.8		58.5
Percent of Normal													222	35	143		156	117	172								137
Evanston								None					0.96	0.18	0.06		0.03	T	0.08								1.31
1981-2010 Normals													1.17	1.04	0.58		0.54	0.61	0.86	1.15	1.77	1.24	0.61	0.96	1.31		4.80
Percent of Normal													82	17	10		6	0	9								27
Greybull								None					1.12	T	0.03		0.04	0.22	0.18								1.59
1981-2010 Normals													0.60	0.30	0.28		0.23	0.18	0.40	0.71	1.65	1.20	0.66	0.42	0.88		1.99
Percent of Normal													187	0	11		17	122	45								80
Station Name: Airports								Drought Conditions					Oct 2013	Nov 2013	Dec 2013		Jan 2014	Feb 2014	Mar 2014	Apr 2014	May 2014	Jun 2014	Jul 2014	Aug 2014	Sep 2014		Total for Water Year
Lander								None					3.08	0.13	0.69		0.61	0.19	1.18								5.88
1981-2010 Normals													1.29	0.86	0.58		0.41	0.58	1.16	1.87	2.20	1.27	0.78	0.61	1.05		4.88
Percent of Normal													239	15	119		149	33	102								120
Snowfall													21.9	3.5	13.1		8.9	3.8	13.9								65.1
1981-2010 Normals													9.8	13.1	10.1		7.6	10.3	16.1	16.8	4.8	0.1	0.0	0.0	2.7		67.0
Percent of Normal													223	27	130		117	37	86								97
Riverton								None					1.94	0.03	0.28		0.68	0.22	0.50								3.65
1981-2010 Normals													0.89	0.50	0.32		0.24	0.27	0.55	1.30	1.72	1.28	0.89	0.57	0.90		2.77
Percent of Normal													218	6	88		283	81	91								132
Snowfall													17.5	1.5	6.8		11.1	5.0	3.4								45.3
Rock Springs								D0					0.86	0.03	0.18		0.07	0.08	0.43								1.65
1981-2010 Normals													0.87	0.49	0.50		0.45	0.48	0.68	0.91	1.21	0.79	0.64	0.62	0.92		3.47
Percent of Normal													99	6	36		16	17	63								48
Sheridan								None					2.47	0.17	1.12		0.64	1.21	1.69								7.30
1981-2010 Normals													1.41	0.71	0.56		0.56	0.54	0.98	1.60	2.35	2.12	1.18	0.72	1.43		4.76
Percent of Normal													175	24	200		114	224	172								153
Worland								None					1.78	0.12	0.12		0.25	0.13	0.40								2.80
1981-2010 Normals													0.69	0.35	0.23		0.23	0.19	0.46	0.86	1.42	1.15	0.71	0.43	0.85		2.15
Percent of Normal													258	34	52		109	68	87								130
Station Name: COOPS								Drought Conditions					Oct 2013	Nov 2013	Dec 2013		Jan 2014	Feb 2014	Mar 2014	Apr 2014	May 2014	Jun 2014	Jul 2014	Aug 2014	Sep 2014		Total for Water Year
Afton								None					2.98	0.71	0.93		1.16	2.40	1.53								9.71
1981-2010 Normals													1.63	2.04	1.25		1.40	1.09	1.40	1.54	2.26	1.97	1.43	1.25	1.46		8.25
Percent of Normal													183	48	74		83	220	109								118
Snowfall													6.5	8.5	12.3		17.3	29.0	11.3								84.9
Bitter Creek 4NE								None					0.97	0.05	0.39		0.27	0.35	0.68								2.71
1981-2010 Normals													0.66	0.31	0.51		0.28	0.36	0.30	0.65	1.09	0.70	0.60	0.75	0.73		2.42
Percent of Normal													147	16	76		96	97	227								112
Cody								None					1.41	0.30	0.42		0.93	1.78	0.55								5.39
1981-2010 Normals													0.89	0.48	0.33		0.33	0.33	0.56	1.06	1.82	1.68	1.11	0.91	1.06		2.92
Percent of Normal													158	63	127		282	539	98								185
Snowfall													7.0	4.0	6.5		20.0	29.0	3.3								69.8
1981-2010 Normals													4.3	6.3	8.0		7.8	6.7	6.9	6.3	0.8	0.0	0.0	0.0	0.2		40.0
Percent of Normal													163	63	81		256	433	48								175
Dubois								None					3.23	0.37	0.35		0.35	1.12	0.64								6.06
1981-2010 Normals													0.81	0.57	0.28		0.24	0.38	0.40	1.10	1.64	1.28	1.11	0.86	1.24		2.68
Percent of Normal													399	65	125		146	295	160								226
Snowfall													19.5	5.0	8.0		7.2	25.6	13.6								78.9
1981-2010 Normals													3.0	5.8	5.1		3.9	5.7	6.0	8.5	3.9	0.6	0.0	0.0	2.6		29.5
Percent of Normal													650	86	157		185	449	227								267
Fossil Butte National Monument								None					2.14	0.43	1.08		0.39	1.35	0.71								6.10
1981-2010 Normals													1.11	0.86	0.74		0.49	0.68	0.82	0.98	1.41	1.03	0.85	0.93	1.10		4.70
Percent of Normal													193	50	146		80	199	87								130
Snowfall													6.5	6.8	14.8		8.4	20.5	8.7								65.7
Green River								D0					3.10	0.15	1.10		0.05	0.35	1.05								5.80
1981-2010 Normals													0.81	0.41	0.44		0.34	0.43	0.71	0.85	1.23	0.98	0.55	0.68	0.90		3.14
Percent of Normal													383	37	250		15	81	148								185
Snowfall													10.5	1.8	10.5		1.6	3.5	2.5								30.4
1981-2010 Normals													0.5	3.8	6.5		4.6	7.3	5.0	3.9	0.6	0.0	0.0	0.0	0.0		27.7
Percent of Normal													2100	47	162		35	48	50								110
Station Name: COOPS								Drought Conditions					Oct 2013	Nov 2013	Dec 2013		Jan 2014	Feb 2014	Mar 2014	Apr 2014	May 2014	Jun 2014	Jul 2014	Aug 2014	Sep 2014		Total for Water Year
Jeffrey City								None					2.08	0.17	0.72		0.39	0.13	1.13								4.62
1981-2010 Normals													0.91	0.59	0.42		0.31	0.41	0.86	1.27	1.85	1.15	0.89	0.60	0.80		3.50
Percent of Normal													229	29	171		126	32	131								132
Snowfall													14.0	2.0	9.0		5.0	2.0	14.0								46.0
1981-2010 Normals													7.3	6.6	5.5		4.6	6.7	9.4	10.2	4.9	0.4	0.0	0.0	1.4		40.1
Percent of Normal													192	30	164		109	30	149								115
Kaycee								None					3.01	0.30	0.48		0.16	0.38	0.71								5.04
1981-2010 Normals													1.04	0.57	0.31		0.30	0.34	0.74	1.46	2.37	1.84	1.42	0.80	1.18		3.30
Percent of Normal													289	53	155		53	112	96								153
Snowfall													11.5	5.0	9.5		3.2	7.1	2.0								38.3
1981-2010 Normals													1.5	4.2	6.0		5.9	6.3	8.0	4.7	0.6	0.1	0.0	0.0	0.2		31.9
Percent of Normal													767	119	158		54	113	25								120
Moose								None					1.51	1.54	2.40		1.78	4.48	4.77								16.48
1981-2010 Normals													1.47	2.64	2.67		2.58	1.82	1.62	1.49	1.88	1.61	1.29	1.29	1.44		12.80
Percent of Normal													103	58	90		69	246	294								129
Snowfall													6.0	12.4	26.5		29.8	48.3	49.5								172.5
1981-2010 Normals													4.8	24.1	44.7		36.9	26.6	15.9	7.4	2.2	0.0	0.0	0.0	0.2		153.0
Percent of Normal													125	51	59		81	182	311								113
Old Faithful								None					1.23	2.47	2.05		1.89	2.90	6.43								16.97
1981-2010 Normals													1.66	2.29	3.16		2.11	1.99	2.21	2.21	2.80	2.47	1.55	1.46	1.46		13.42
Percent of Normal													74	108	65		90	146	291								126
Snowfall													9.0	13.5	23.5		21.0	46.0	76.5								189.5
1981-2010 Normals													7.7	31.7	43.8		37.5	31.1	26.8	19.3	7.3	1.2	0.0	0.0	1.4		178.6
Percent of Normal													117	43	54		56	148	285								106
Powell Field Station								None					0.66	0.07	0.08		0.18	0.65	0.15								1.79
1981-2010 Normals													0.56	0.18	0.13		0.21	0.13	0.29	0.51	1.40	1.35	0.87	0.52	0.65		1.50
Percent of Normal													118	39	62		86	500	52								119
Snowfall													0.5	2.0	3.0		3.0	10.7	1.0								20.2
1981-2010 Normals													1.2	1.3	1.2		2.3	0.5	2.5	0.5	0.5	0.0	0.0	0.0	0.1		9.0
Percent of Normal													42	154	250		130	2140	40								224
Riverton (downtown)								None					1.72	0.04	0.31		0.63	0.14	0.49								3.33
1981-2010 Normals													0.85	0.41	0.24		0.28	0.33	0.56	0.98	1.45	1.21	0.78	0.50	0.83		2.67
Percent of Normal													202	10	129		225	42	88								125
Snowfall													9.5	1.1	5.9		10.1	4.9	5.5								37.0
1981-2010 Normals													3.7	4.3	4.8		4.8	6.0	5.9	6.1	1.2	0.0	0.0	0.0	0.3		29.5
Percent of Normal													257	26	123		210	82	93								125
Thermopolis								None					2.82	0.22	0.46		0.46	0.20	0.54								4.70
1981-2010 Normals													1.26	0.80	0.46		0.35	0.45	0.87	1.46	1.86	1.51	0.88	0.58	1.23		4.19
Percent of Normal													224	28	100		131	44	62								112
Snowfall													9.0	4.0	10.0		6.5	4.5	1.0								35.0
1981-2010 Normals													2.4	3.7	4.5		5.6	4.6	2.5	2.8	0.4	0.0	0.0	0.0	0.2		23.3
Percent of Normal													375	108	222		116	98	40								150
Drought Classifications on April 15, 2014     |      XX.X / M - Data partially or completely missing

Even with a relatively dry summer the 12 month precipitation totals ending on April 20 2014 are impressive.

Star Valley Ranch  30.92 inches
Star Valley Ranch west side 26.80 inches
5 SSE Smoot  25.99  inches
1.5 SE Thayne 24.08 inches