401
ACUS48 KWNS 260958
SWOD48
SPC AC 260956
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0356 AM CST THU FEB 26 2026
VALID 011200Z - 061200Z
..DISCUSSION
EARLY IN THE FORECAST PERIOD A TRANSITION ACROSS THE WESTERN US WILL
TAKE PLACE AS THE LOW-AMPLITUDE RIDGE OVER THE GREAT BASIN/SOUTHWEST
SHIFTS EASTWARD, GIVING WAY TO AN AMPLIFYING TROUGH OVER THE WEST.
SEVERAL SPEED MAXIMA ARE FORECAST TO TRAVERSE THE FLOW WHILE IT
REMAINS PRIMARILY NORTHWESTERLY OVER THE CENTRAL US EARLY IN THE
PERIOD. AT THE SURFACE, UNCERTAINTY REMAINS REGARDING THE SOUTHERN
EXTENT OF THE ARCTIC FRONT PUSHING INTO THE PLAINS ON DAY 3.
UNCERTAINTIES IN THE POSITION OF THIS FRONT WILL CAUSE LOW
CONFIDENCE IN THE PROJECTED QUALITY OF THE LOW-LEVEL MOISTURE
RECOVERY ACROSS THE SOUTHERN PLAINS THROUGH TUESDAY. AS THE
UPPER-AIR PATTERN ACROSS THE CENTRAL US TRANSITIONS FROM
NORTHWESTERLY TO SOUTHWESTERLY, AND RETURN FLOW COMMENSES, THE
SHALLOW NATURE OF THE MODIFIED ARCTIC AIRMASS MAY INITIALLY LIMIT
THE NORTHWARD PENETRATION OF THE RICHEST THETA-E AIR.
AS THE PERIOD PROGRESSES INTO WEDNESDAY AND THURSDAY, ENSEMBLE
GUIDANCE REMAINS IN GENERAL AGREEMENT REGARDING THE TRANSITION TO AN
AMPLIFIED WESTERN TROUGH AND CENTRAL-TO-EASTERN RIDGE. HOWEVER, THE
TIMING AND PHASING OF INDIVIDUAL SHORTWAVES MOVING INTO THE PLAINS
REMAINS A SOURCE OF FORECAST UNCERTAINTY.
THE FIRST MEANINGFUL SHORTWAVE IS FORECAST TO EJECT INTO THE PLAINS
EARLY WEDNESDAY, INDUCING SURFACE CYCLOGENESIS THAT SHOULD SUPPORT A
NORTHWARD ADVANCEMENT OF THE WARM SECTOR. ANY SEVERE RISK WITH THIS
TROUGH ON WEDNESDAY (DAY 7) WILL BE PREDICATED ON THE EVOLUTION OF
THE MOISTURE RETURN ON PRIOR DAYS.
ON THURSDAY, A SECOND, MORE POTENT TROUGH IS FORECAST TO APPROACH
THE PLAINS. CURRENT ENSEMBLE GUIDANCE SHOWS QUITE A BIT MORE
VARIANCE WITH THE TIMING, AMPLITUDE, AND EVOLUTION OF THIS SECOND
TROUGH. SOME GUIDANCE BRINGS THIS WAVE OUT AS SINGLE, POTENT TROUGH,
WITH OTHER GUIDANCE SUGGESTING A SERIES OF MORE SUBTLE SHORTWAVE
TROUGHS EJECTING INTO THE PLAINS FROM THURSDAY INTO SATURDAY. THESE
DISCREPANCIES WILL HAVE AN IMPACT ON THE LOCATION, TIMING, AND
MAGNITUDE OF ANY POTENTIAL SEVERE WEATHER THREAT.
DESPITE THESE TIMING DIFFERENCES, THE SYNOPTIC SETUP (INCREASING
LOW-LEVEL MOISTURE, STRENGTHENING SOUTHWEST FLOW ALOFT, REPEATED
CYCLOGENESIS) IS FAVORABLE FOR ORGANIZED SEVERE WEATHER OVER THE
PLAINS AND LOWER MISSISSIPPI VALLEY. WHILE THE SEVERE WEATHER THREAT
SHOULD INCREASE BY WEDNESDAY AND THURSDAY (DAYS 7 AND 8), THE
SPECIFIC ORIENTATION OF FRONTAL BOUNDARIES AND THE NORTHWARD EXTENT
OF THE MOISTURE RETURN WILL BE HIGHLY DEPENDENT ON THE EVOLUTION OF
THE UPPER-LOWS. GIVEN THAT MODELS TEND TO STRUGGLE WITH HANDLING THE
DETAILS OF PATTERN CHANGES, WILL HOLD OFF ON TRYING TO HIGHLIGHT ANY
SPECIFIC CORRIDOR FOR SEVERE PROBABILITIES FOR WEDNESDAY AND
THURSDAY AT THIS TIME.
..MARSH.. 02/26/2026
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