Severe Storm Outlook Narrative (AC)
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000
ACUS48 KWNS 040901
SWOD48
SPC AC 040859

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0359 AM CDT MON MAY 04 2015

VALID 071200Z - 121200Z

...DISCUSSION...
UNCERTAINTY WITHIN THE MEDIUM RANGE MODEL OUTPUT...CONCERNING AN
AMPLIFYING SHORT WAVE TROUGH EMERGING FROM A STRONGER BELT OF
MID-LATITUDE WESTERLIES...DIGGING JUST INLAND OF THE PACIFIC COAST
AT THE OUTSET OF THE FORECAST PERIOD...APPEARS TO BE DECREASING.  IN
GENERAL...IT APPEARS THAT AN EMBEDDED MID-LEVEL LOW WILL EVOLVE AS
THIS IMPULSE GRADUALLY TURNS ACROSS THE SOUTHERN GREAT
BASIN...TOWARD THE FOUR CORNERS REGION...LATE THIS WEEK.  PHASING
WITH THE SUBTROPICAL STREAM DOES APPEAR POSSIBLE...BEFORE THIS
SYSTEM BEGINS ACCELERATING EAST NORTHEASTWARD.  GUIDANCE CONTINUES
TO INDICATE SATURDAY AS THE MOST LIKELY DAY THAT THIS IMPULSE
EMERGES FROM SOUTHERN INTERMOUNTAIN REGION...CONTRIBUTING TO A
DEEPENING SURFACE CYCLONE OVER THE CENTRAL HIGH PLAINS.  INCREASING
LARGE-SCALE FORCING FOR ASCENT...STRENGTHENING VERTICAL SHEAR...AND
THE CONTINUING PRESENCE OF MOIST...POTENTIALLY UNSTABLE AIR PROBABLY
WILL BE SUFFICIENT TO SUPPORT ORGANIZED SEVERE
CONVECTION...INCLUDING SUPERCELLS...ACROSS THE CENTRAL AND SOUTHERN
PLAINS.

AS THIS UPPER IMPULSE...AND ASSOCIATED SURFACE CYCLONE...PROGRESS
EASTWARD IN SUBSEQUENT DAYS...SEVERE PROBABILITIES REMAIN BELOW 15
PERCENT AT THIS TIME DUE TO INCREASING UNCERTAINTIES/DECREASING
PATTERN PREDICTABILITY.

..KERR.. 05/04/2015


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