Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS02 KWNS 011730
SWODY2
SPC AC 011730

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT WED JUL 01 2015

VALID 021200Z - 031200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM A PORTION OF THE SOUTHERN
PLAINS THROUGH THE OZARKS TO SOUTHERN APPALACHIANS...

...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING THE SLIGHT RISK TO
THE COAST OF THE CAROLINAS...

...SUMMARY...
SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS MUCH OF THE
SOUTHERN HALF OF THE COUNTRY THURSDAY.  SEVERE STORMS ARE MOST
LIKELY FROM PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS TO THE
SOUTHERN APPALACHIANS.

...SYNOPSIS...
AN UPPER RIDGE SHIFTING WNWWD FROM THE FOUR CORNERS REGION THROUGH
THE GREAT BASIN DURING DAY 1 SHOULD REMAIN CENTERED OVER NV ON
THURSDAY...WITH WEAK HEIGHT FALLS ACROSS THE GREAT PLAINS.  THIS
WILL RESULT IN THE PRIMARY BAND OF NORTHWESTERLY FLOW ALOFT TO
BECOME ESTABLISHED DURING DAY 2 FROM THE NORTHERN ROCKIES THROUGH
THE CENTRAL AND SOUTHERN PLAINS...AND THEN EASTWARD THROUGH THE TN
VALLEY TO THE MID-ATLANTIC REGION.  A SERIES OF PROGRESSIVE
SHORTWAVE TROUGHS EMBEDDED WITHIN THIS MID- TO UPPER-LEVEL FLOW
REGIME WILL AID IN TSTM DEVELOPMENT FROM THE CENTRAL AND SOUTHERN
PLAINS THROUGH THE TN VALLEY AND SOUTHERN APPALACHIANS REGION.

...SOUTHERN AND CENTRAL PLAINS TO SOUTHERN APPALACHIANS...
MODELS CONTINUE TO INDICATE AN MCS SHOULD BE ONGOING AT 12Z THURSDAY
FROM SOUTHERN MO/NORTHERN AR INTO PORTIONS OF KY/TN.  THIS ACTIVITY
IS EXPECTED TO BE FOCUSED WITHIN A WARM ADVECTION ZONE ALONG THE
NOSE OF LLJ THAT SHOULD VEER THROUGH THE DAY AS IT TRANSLATES ACROSS
THE LOWER MS VALLEY TOWARD THE SOUTHERN APPALACHIANS.  WHILE THIS
MCS MAY NOT BE SEVERE AT 12Z...DIABATIC HEATING AND STEEPENING
LOW-LEVEL LAPSE RATES IN THE WAKE OF THIS ACTIVITY AND ALONG ANY
BOUNDARIES RELATED TO DIFFERENTIAL HEATING AND/OR CONVECTIVE OUTFLOW
SHOULD PROVE ADEQUATE TO RE-INVIGORATE CONVECTION BY MID-DAY.  GIVEN
THE PRESENCE OF AFOREMENTIONED STRONGER FLOW ALOFT /35-45 KT/
ENHANCING BULK SHEAR AND FORCING FOR ASCENT WITH THE LEAD SHORTWAVE
TROUGH WITHIN A MODERATELY UNSTABLE AIR MASS...NEW STORMS SHOULD BE
CAPABLE OF PRODUCING PRIMARILY DAMAGING WINDS AS THE GREATEST RISK.
WEAK MIDLEVEL LAPSE RATES SHOULD LIMIT THE POTENTIAL FOR SEVERE
HAIL.

MEANWHILE...WEAK MIDLEVEL HEIGHT FALLS ARE EXPECTED TO SPREAD ACROSS
THE CENTRAL PLAINS AHEAD OF A SHORTWAVE TROUGH...CURRENTLY MOVING
EAST ACROSS SOUTHERN ALBERTA PER WATER VAPOR IMAGERY...THAT WILL
TRACK FROM THE DAKOTAS INTO THE MID MS VALLEY REGION DURING DAY 2.
THE SOUTHWESTERN EXTENT OF THIS THROUGH IS EXPECTED TO SPREAD ACROSS
THE SOUTHERN PLAINS BY THURSDAY NIGHT.  A SURFACE FRONT EXPECTED TO
EXTEND FROM SOUTHWEST MO WSWWD THROUGH FAR NORTHERN OK TO THE NRN
TX/OK PANHANDLES REGION AT 12Z IS EXPECTED TO BE THE PRIMARY FOCUS
FOR STRONG AFTERNOON STORM DEVELOPMENT.  A SIMILAR POTENTIAL WILL
EXIST ACROSS SOUTHERN MO AND NORTHERN AR AS A SURFACE LOW AND
TRAILING PORTION OF THE SAME FRONT SPREAD TO THE SOUTHEAST ACROSS
THESE AREAS.  PRE-FRONTAL PW VALUES SHOULD BE UP TO AROUND 2 INCHES
AND COMBINED WITH DIABATIC HEATING AND THE EASTERN EXTENT OF 6.5-7
C/KM MIDLEVEL LAPSE RATES SHOULD RESULT IN A MODERATELY TO VERY
STRONGLY UNSTABLE ENVIRONMENT.  STRENGTHENING DEEP-LAYER SHEAR WILL
SUPPORT ORGANIZED UPDRAFTS WHILE POTENTIAL REMAINS FOR A SQUALL LINE
TO EVOLVE FROM THE MO/AR BORDER WWD ALONG THE FRONT THROUGH NORTHERN
OK INTO THE PANHANDLES REGION...AND ADVANCE SOUTHWARD...GIVEN
STRENGTHENING NWLY FLOW ALOFT.  SEVERE WIND AND HAIL WILL BE THE
PRIMARY THREATS...WITH HIGHER SEVERE PROBABILITIES IN LATER OUTLOOKS
BEING POSSIBLE AS OVERALL STORM COVERAGE...INTENSITY AND EVOLUTION
BECOMES MORE CERTAIN.

..PETERS.. 07/01/2015



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