144
ACUS02 KWNS 281720
SWODY2
SPC AC 281718
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1118 AM CST SUN DEC 28 2025
VALID 291200Z - 301200Z
..NO SEVERE THUNDERSTORM AREAS FORECAST
..SUMMARY
ASIDE FROM PARTS OF THE LOWER RIO GRANDE VALLEY, THE RISK FOR
THUNDERSTORMS APPEARS NEGLIGIBLE ACROSS MUCH OF THE U.S. MONDAY
THROUGH MONDAY NIGHT.
..DISCUSSION
WITHIN ONE BRANCH OF WESTERLIES EMANATING FROM THE NORTHERN
MID-LATITUDE PACIFIC, MODELS INDICATE THAT BROAD MID-LEVEL RIDGING
WILL BE MAINTAINED ACROSS BRITISH COLUMBIA AND THE PACIFIC NORTHWEST
THROUGH THE CANADIAN/NORTHERN U.S. ROCKIES AND ADJACENT
PRAIRIES/GREAT PLAINS THROUGH THIS PERIOD. DOWNSTREAM TROUGHING MAY
UNDERGO FURTHER AMPLIFICATION AS A SURFACE COLD INTRUSION PROGRESSES
SOUTH/SOUTHEASTWARD THROUGH THE GULF BASIN. HOWEVER, THE PRIMARY
EMBEDDED SHORT WAVE PERTURBATION IS FORECAST TO RAPIDLY PIVOT EAST
AND NORTHEAST OF THE LOWER GREAT LAKES AND OHIO VALLEY TOWARD THE
CANADIAN MARITIMES AND NORTHWESTERN ATLANTIC MONDAY THROUGH MONDAY
NIGHT. WHILE THE CENTER OF AN ASSOCIATED BROAD, SLOWLY DEEPENING
AND OCCLUDING SURFACE CYCLONE SHIFTS EAST-NORTHEAST OF LAKE
HURON/GEORGIAN BAY THROUGH SOUTHERN QUEBEC, IT APPEARS A SECONDARY
SURFACE LOW MAY DEVELOP ACROSS NORTHERN NEW ENGLAND INTO THE LOWER
ST. LAWRENCE VALLEY. IN ITS WAKE, THE TRAILING COLD FRONT IS
FORECAST TO RAPIDLY ADVANCE EAST/SOUTHEAST OF THE APPALACHIANS, AND
WELL OFFSHORE OF MUCH OF THE ATLANTIC SEABOARD BY 12Z TUESDAY.
...LOWER GREAT LAKES INTO NEW ENGLAND
NAM AND RAPID REFRESH FORECAST SOUNDINGS INDICATE THAT
LOWER/MID-TROPOSPHERIC WARMING AND MOISTENING, PRECEDING THE
SECONDARY SURFACE FRONTAL WAVE DEVELOPMENT, WILL CONTRIBUTE TO WEAK
ELEVATED DESTABILIZATION ACROSS PORTIONS OF EASTERN NEW YORK STATE
THROUGH NEW ENGLAND DURING THE DAY MONDAY. THIS MAY CONTRIBUTE TO
DEEPER CONVECTIVE DEVELOPMENT EMBEDDED WITHIN AN EVOLVING BROADER
PRECIPITATION SHIELD. THE EXTENT TO WHICH THIS COULD BECOME CAPABLE
OF PRODUCING LIGHTNING REMAINS A BIT UNCLEAR, BUT PROBABILITIES FOR
WEAK THUNDERSTORMS STILL SEEM BEST CHARACTERIZED AS LESS THAN 10
PERCENT.
..LOWER RIO GRANDE VALLEY
NAM AND RAPID REFRESH FORECAST SOUNDINGS, AND OTHER MODEL OUTPUT,
SUGGEST THAT WIDELY SCATTERED WEAK THUNDERSTORM ACTIVITY IS POSSIBLE
ALONG OR JUST BEHIND THE COLD FRONT AS IT ADVANCES ACROSS DEEP SOUTH
TEXAS LATE TONIGHT. TIMING OF THE FRONTAL PASSAGE AND ASSOCIATED
CONVECTION THROUGH THE LOWER RIO GRANDE AROUND BROWNSVILLE REMAINS
UNCERTAIN, BUT LOW THUNDERSTORM PROBABILITIES MAY LINGER AN HOUR OR
TWO BEYOND 12Z MONDAY.
..KERR.. 12/28/2025
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