Sunday, August 29, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 290554
SWODY1
SPC AC 290552

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1252 AM CDT SUN AUG 29 2010

VALID 291200Z - 301200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
AN AMPLIFIED LONGWAVE PATTERN WILL REMAIN OVER THE CONUS THROUGH
TONIGHT. WHILE AN EASTERN CONUS UPPER RIDGE REMAINS CENTERED
ALONG/EAST OF THE APPALACHIANS...BASAL PORTION OF A WESTERN STATES
LONGWAVE TROUGH WILL SHIFT GENERALLY EASTWARD OVER THE GREAT BASIN
TODAY AS IT TAKES ON A NEUTRAL TO SLIGHTLY NEGATIVE TILT BY EARLY
MONDAY.

...AZ...
WITH A MOIST AIRMASS GENERALLY REMAINING ACROSS THE EASTERN HALF TO
TWO-THIRDS OF AZ TODAY...STRENGTHENING SOUTHWESTERLY FLOW ALOFT IS
EXPECTED IN CONJUNCTION WITH THE EASTWARD-SHIFTING SOUTHERN PORTION
OF THE WESTERN STATES UPPER TROUGH. CURRENT THINKING IS THAT TSTMS
WILL INCREASE/SPREAD NORTHEASTWARD THROUGH THE
AFTERNOON/EVENING...WITH SUCH DEVELOPMENT EXPECTED ACROSS THE DESERT
FLOOR OF SOUTHERN AZ AND ESPECIALLY THE RIM VICINITY/MOUNTAINS OF
SOUTHEAST AZ. GIVEN THE AFOREMENTIONED STRENGTHENING FLOW ALOFT
/30-40 KT AT 500 MB/...AMPLE VERTICAL SHEAR COUPLED WITH A
RELATIVELY HIGH PWAT ENVIRONMENT/SUFFICIENT BUOYANCY WILL BE
SUPPORTIVE OF SOME ORGANIZED STRONG/SEVERE STORMS...POTENTIALLY
INCLUDING A FEW SUPERCELLS. DAMAGING WINDS WILL BE THE PRIMARY
CONCERN...WITH MARGINALLY SEVERE HAIL ALSO POSSIBLE WITH STORMS THAT
EXHIBIT A DEGREE OF UPDRAFT ROTATION.

...EASTERN GREAT BASIN/CENTRAL ROCKIES...
WHILE APPRECIABLE LARGE SCALE FORCING WILL NOT ARRIVE UNTIL LATE IN
THE PERIOD...OTHER MORE ISOLATED HIGH BASED TSTMS WILL BE POSSIBLE
ESPECIALLY THIS AFTERNOON/EVENING WITHIN A RESIDUAL MOISTURE-RICH
AIRMASS ACROSS PORTIONS OF EASTERN UT/WESTERN CO INTO WY. A
WELL-MIXED BOUNDARY LAYER/HIGH BASED NATURE OF THE STORMS IN
CONJUNCTION WITH STRENGTHENING SOUTHWESTERLY FLOW ALOFT WILL YIELD
SOME TSTMS CAPABLE OF STRONG/SEVERE WIND GUSTS.

...LOWER MS VALLEY/CENTRAL GULF COAST/SOUTHEAST STATES...
WEAK SURFACE LOW SHOULD MOVE INLAND/MINOR ACROSS THE LOWER MS VALLEY
ON THE WESTERN PERIPHERY OF THE EASTERN STATES ANTICYCLONE. WHILE
LOW LEVEL SHEAR SHOULD REMAIN MODEST ATTENDANT TO THE
LOW...PERIPHERAL CLUSTERS/CORRIDORS OF GENERALLY NORTHWESTWARD
MOVING TSTMS SHOULD INCREASE DURING THE AFTERNOON ACROSS A BROAD
PORTION OF THE REGION. SOME DOWNBURST POTENTIAL COULD EXIST WHERE
STRONGER LOW LEVEL HEATING OCCURS...BUT SUCH A RISK CURRENTLY
APPEARS TOO LIMITED FOR SEVERE PROBABILITIES.

..GUYER/GRAMS.. 08/29/2010

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