Severe Storm Outlook Narrative (AC)
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
ACUS01 KWNS 200531
SWODY1
SPC AC 200529

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 AM CDT SAT SEP 20 2014

VALID 201200Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE UPPER MS VALLEY...

...THERE IS A SLGT RISK OF SVR TSTMS FROM LOWER MI TO NRN MO...

...SUMMARY...
SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED SATURDAY FROM
SOUTHWESTERN LOWER MICHIGAN TO NORTHERN MISSOURI. LARGE HAIL AND
STRONG WINDS WILL BE POSSIBLE. SEVERE WIND AND MARGINALLY SEVERE
HAIL ARE ALSO LIKELY ACROSS MUCH OF NORTHERN MINNESOTA AND VICINITY.
A LOWER THREAT OF SEVERE WEATHER EXISTS ACROSS NEVADA AND WESTERN
UTAH.

...UPPER MS VALLEY...

EARLY MORNING WV IMAGERY CLEARLY DEPICTS A STRONG SHORT-WAVE TROUGH
OVER CNTRL AB...DIGGING SEWD IN LINE WITH LATEST MODEL GUIDANCE.
00Z GUIDANCE SUGGEST 80KT+ 500MB SPEED MAX WILL TRANSLATE INTO WRN
ND BY 18Z...THEN INTO SWRN MN BY EARLY EVENING.  EXIT REGION OF THIS
FEATURE WILL ENHANCE UVV ACROSS THE RED RIVER VALLEY REGION AND A
STRONGLY FORCED SECONDARY COLD FRONT SHOULD ADVANCE TO A POSITION
OVER ERN ND BY 18Z.  DESPITE THE SOMEWHAT MARGINAL MOISTURE IN PLACE
AHEAD OF THIS SYSTEM...COOLING PROFILES AND STRONG FORCING SHOULD
ENCOURAGE A BAND OF CONVECTION TO DEVELOP ALONG WIND SHIFT BY EARLY
AFTERNOON.  THIS ACTIVITY WILL THEN SPREAD SEWD ACROSS MN AS EXIT
REGION OF JET ADVANCES DOWNSTREAM.  DAMAGING WINDS ARE POSSIBLE WITH
THIS ACTIVITY...ESPECIALLY IF LINEAR MCS EVOLVES AS A FEW HIGH RES
MODELS SUGGEST.  MARGINALLY SEVERE HAIL COULD ALSO ACCOMPANY THE
MORE ROBUST UPDRAFTS.


...MID MS VALLEY TO LOWER MI...

BAND OF STRONG THUNDERSTORMS HAS EVOLVED FROM NERN NEB INTO SERN MN
AT 05Z.  THIS ACTIVITY APPEARS TO BE AIDED IN PART BY ENTRANCE
REGION OF EJECTING SPEED MAX THAT WILL TRANSLATE INTO SERN CANADA
DURING THE DAY.  WHILE CONVECTION MAY BE ONGOING AT THE BEGINNING OF
THE PERIOD OVER PORTIONS OF NRN LOWER MI...MORE SIGNIFICANT
CONVECTION IS POSSIBLE LATER IN THE DAY AS BOUNDARY LAYER WARMS.  AS
MID-LEVEL SPEED MAX EJECTS INTO SERN CANADA LOW-LEVEL FLOW SHOULD
VEER ACROSS THE MIDWEST AND A CONFLUENCE ZONE SHOULD ESTABLISH
ITSELF FROM EXTREME SERN WI...SWWD INTO NRN MO.  GREATEST BUOYANCY
IS EXPECTED ACROSS THE MID MS VALLEY WHERE SBCAPE COULD APPROACH
3000 J/KG.  AS TEMPERATURES WARM INTO THE MID 80S CINH SHOULD WEAKEN
SUFFICIENTLY FOR SCT TSTMS...LIKELY BY 22Z.  THIS ACTIVITY IS
EXPECTED TO DEVELOP WITHIN INCREASINGLY SHEARED NWLY FLOW REGIME.
LARGE HAIL AND DAMAGING WINDS ARE POSSIBLE WITH ORGANIZED MULTI-CELL
CLUSTERS AND ISOLATED SUPERCELLS.


...GREAT BASIN...

UPPER LOW OFF THE SRN CA COAST IS EXPECTED TO EJECT NEWD ACROSS CA
INTO NV BY THE END OF THE PERIOD.  MID-LEVEL FLOW WILL INCREASE
ACROSS THE LOWER CO RIVER VALLEY INTO THE GREAT BASIN BY AFTERNOON
AND HIGH-BASED CONVECTION THAT EVOLVES ACROSS THIS REGION MAY
ORGANIZE WITHIN DEEP SELY FLOW.  FORECAST SOUNDINGS SUGGEST
ORGANIZED ROTATING UPDRAFTS ARE POSSIBLE BUT PW VALUES ARE NOT
PARTICULARLY HIGH.  GIVEN THE WEAK INSTABILITY WILL MAINTAIN 5
PERCENT SEVERE FOR ISOLATED SEVERE WIND GUSTS AND MARGINALLY SEVERE
HAIL.

..DARROW/COHEN.. 09/20/2014




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.