Severe Storm Outlook Narrative (AC)
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000
ACUS48 KWNS 280959
SWOD48
SPC AC 280957

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0357 AM CST SAT FEB 28 2015

VALID 031200Z - 081200Z

...DISCUSSION...
THE 00Z ECMWF/GFS ARE IN GENERAL AGREEMENT WITH THE EVOLUTION OF THE
UPPER FLOW REGIME DURING DAYS 4-8 /TUE-SAT/.  THE LATE DAY-3
/MON-MARCH 2/ CENTRAL HIGH PLAINS SHORTWAVE TROUGH IS EXPECTED TO
UNDERGO FURTHER DAMPENING AS IT TRACKS NEWD WITHIN A CONFLUENT-FLOW
REGIME ON DAY 4 /TUE-MARCH 3/.  THIS WILL OCCUR AHEAD OF A
LARGE-SCALE MID-UPPER-LEVEL TROUGH DEVELOPING E/SEWD ACROSS THE NRN
PLAINS/UPPER MS VALLEY TO CENTRAL ROCKIES.  BY THE START OF DAY 5
/WED-MARCH 4/...THE LARGE-SCALE NRN-STREAM TROUGH SHOULD BE PHASING
WITH A SRN CA TROUGH AS THIS LATTER FEATURE MOVES INTO AZ/NM/NRN
MEXICO.  THIS NEARLY FULL-LATITUDE POSITIVELY TILTED LONGWAVE TROUGH
WILL PROGRESS EWD ACROSS MUCH OF THE PLAINS STATES DURING DAY
5...AND THEN THROUGH THE ERN STATES ON DAY 6 /THU-MARCH 5/.  AS THIS
TROUGH MOVES EWD...A RIDGE WILL BUILD ACROSS THE WRN STATES
RESULTING IN A RIDGE WEST AND TROUGH IN THE EAST BEING THE MAIN
LARGE-SCALE PATTERN INTO THE LATTER PART OF THE WEEK.

ON DAY 4 /TUE/...A SURFACE LOW ATTENDANT TO THE CENTRAL HIGH PLAINS
SHORTWAVE TROUGH WILL TRACK FROM WRN KS THROUGH THE SRN GREAT LAKES
TO SRN QUEBEC.  THE TRAILING COLD FRONT WILL ADVANCE EWD THROUGH THE
MID MS VALLEY INTO THE OH/TN VALLEYS AND SWD INTO AR AND THE SRN
PLAINS.  THIS SAME FRONT WILL PROGRESS EWD AND SWD ON DAY 5 /WED/
THROUGH MUCH OF THE REST OF THE ERN U.S. AND THROUGH THE LOWER MS
VALLEY/CENTRAL GULF COAST STATES AND TX.  THE TSTM POTENTIAL WILL
INCREASE IN AREAL COVERAGE ALONG THE FRONT AND WARM SECTOR DURING
DAYS 4/5 PRIMARILY FROM THE SRN PLAINS TO PORTIONS OF THE OH/TN
VALLEYS AND INTO THE LOWER MS VALLEY AND NWRN/CENTRAL GULF COAST
STATES.  STRENGTHENING DEEP-LAYER AND LOW-LEVEL WINDS/SHEAR WILL BE
MORE THAN ADEQUATE FOR ORGANIZED STORMS FROM A PORTION OF THE SRN
PLAINS TO OZARKS ON DAY 4 AND THEN ACROSS PARTS OF THE NWRN-CENTRAL
GULF COAST STATES ON DAY 5.  WHILE A FEW STRONG TO SEVERE STORMS
WILL BE POSSIBLE ON TUE/WED...WEAK INSTABILITY ACROSS THE WARM
SECTOR SUGGESTS ANY SEVERE POTENTIAL WILL REMAIN BELOW 15 PERCENT.

..PETERS.. 02/28/2015



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