SPC AC 200830
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CST SUN DEC 20 2015
VALID 221200Z - 231200Z
...THERE IS A MRGL RISK OF SVR TSTMS MAINLY TUESDAY NIGHT ACROSS
PARTS OF THE SOUTHEASTERN PLAINS...WESTERN AND CENTRAL GULF COAST
REGION...
...SUMMARY...
THUNDERSTORMS WILL IMPACT PORTIONS OF THE SOUTHEASTERN PLAINS...AND
PORTIONS OF THE WESTERN INTO CENTRAL GULF COAST REGION...TUESDAY
THROUGH TUESDAY NIGHT...WITH AT LEAST SOME RISK FOR SEVERE WEATHER.
...SYNOPSIS...
MODELS SUGGEST UPPER TROUGH AMPLIFICATION WILL CONTINUE OVER THE
INTERIOR U.S...MAINLY EAST OF THE CENTRAL/SOUTHERN ROCKIES THROUGH
THE CENTRAL/SOUTHERN PLAINS...DOWNSTREAM OF A STRONG MID/UPPER JET
WHICH MAY CONTINUE TO NOSE INLAND ACROSS THE PACIFIC COAST. AT
LEAST SOME PHASING WITH A SIGNIFICANT IMPULSE EMERGING FROM THE
LOWER LATITUDE EASTERN PACIFIC IS POSSIBLE...AS THE LATTER FEATURE
ACCELERATES NORTHEAST OF THE MEXICAN PLATEAU THROUGH THE WESTERN
GULF OF MEXICO. IN RESPONSE TO THESE DEVELOPMENTS...SECONDARY
SURFACE CYCLOGENESIS IS FORECAST WITHIN LEE SURFACE TROUGHING...FROM
THE HIGH PLAINS OF SOUTHEAST COLORADO THROUGH THE CENTRAL PLAINS.
AND CONSIDERABLE STRENGTHENING OF LOWER/MID TROPOSPHERIC WIND FIELDS
ARE LIKELY LATE TUESDAY THROUGH TUESDAY NIGHT ACROSS THE SOUTHERN
PLAINS THROUGH LOWER MISSISSIPPI VALLEY...WESTERN AND CENTRAL GULF
COAST REGION. THIS MAY INCLUDE AT LEAST ONE BRANCH OF STRENGTHENING
SOUTHERLY 850 MB FLOW /TO 40-50+ KT/...FROM THE WESTERN GULF OF
MEXICO THROUGH PORTIONS OF THE OZARK PLATEAU AND LOWER MISSISSIPPI
VALLEY.
...SERN PLAINS THROUGH WRN AND CNTRL GULF COAST REGION...
CONSIDERABLE THUNDERSTORM ACTIVITY MAY BE ONGOING EARLY TUESDAY NEAR
OR PERHAPS OFFSHORE OF CENTRAL GULF COASTAL AREAS...AND LARGE-SCALE
FORCING FOR ASCENT MAY MAINTAIN THIS ACTIVITY IN THE SAME GENERAL
REGION THROUGH MUCH OF THE DAY. AS THE MAIN SUBTROPICAL IMPULSE
BEGINS IMPACTING THE CENTRAL GULF COAST REGION TUESDAY NIGHT...A
FURTHER INCREASE IN CONVECTIVE COVERAGE AND INTENSITY ARE POSSIBLE
IN THE PRESENCE OF STRENGTHENING SHEAR. THERE SHOULD ALSO BE A
TENDENCY FOR ACTIVITY TO ADVANCE NORTHWARD...EITHER INLAND OF THE
CENTRAL GULF COAST...OR FROM THE NORTHERN GULF OF MEXICO INTO
COASTAL AREAS. SEVERE WEATHER POTENTIAL WILL GENERALLY BE
DETERMINED BY THE EXTENT OF BOUNDARY LAYER DESTABILIZATION
INLAND...WHICH MAY BE HAMPERED BY THE PRESENCE OF COASTAL CONVECTION
THROUGH MUCH OF THE PERIOD...ACROSS LOUISIANA/MISSISSIPPI AND
ALABAMA.
MODELS SUGGEST THAT AT LEAST WEAK BOUNDARY LAYER DESTABILIZATION IS
MORE CERTAIN WITHIN THE EVOLVING WARM SECTOR OF THE DEVELOPING
SURFACE LOW...ACROSS MUCH OF EASTERN TEXAS THROUGH THE ARKLATEX
REGION. THE STRENGTH AND AREAL COVERAGE OF FORCING FOR ASCENT
REMAIN A BIT UNCLEAR...BUT ITS POSSIBLE THAT MID-LEVEL FORCING WITH
THE MID-LATITUDE WAVE COULD CONTRIBUTE TO INCREASING STORM
DEVELOPMENT ACROSS AT LEAST PARTS OF NORTHEAST TEXAS AND THE
ARKLATEX TUESDAY NIGHT. THIS COULD COMMENCE PRIOR TO 23/06Z...BUT
IT SEEMS MORE PROBABLE AFTER. EVEN SO...THE ENVIRONMENT MAY BE
CONDUCIVE TO ORGANIZED CONVECTION...INCLUDING SUPERCELLS.
..KERR.. 12/20/2015
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z