SWODY1
SPC AC 011627
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CDT SAT SEP 01 2007
VALID 011630Z - 021200Z
..NO SVR TSTM AREAS FORECAST...
..ERN ND/NWRN MN...
WATER VAPOR IMAGERY SHOWS A STRONG SHORT WAVE TROUGH MOVING EWD
ACROSS SRN SASKATCHEWAN AND EXTREME ERN MT...WITH A VORTICITY MAX
IMMEDIATELY IN THE WAKE OF THE SHORT WAVE MOVING EWD ACROSS SRN
ALBERTA. THE SYSTEMS ARE FORECAST TO PROGRESS EWD ACROSS THE SRN
CANADIAN PRAIRIE PROVINCES THIS AFTERNOON AND CONTINUING INTO NWRN
ONTARIO TONIGHT. AT THE SURFACE...ONE LOW ASSOCIATED WITH THE SHORT
WAVE TROUGH IS OVER MANITOBA WITH A SURFACE TOUGH EXTENDING SWD INTO
THE CENTRAL HIGH PLAINS. A SECOND LOW IS OVER SASKATCHEWAN WITH A
COLD FRONT TRAILING SWWD FROM THE LOW. THESE SYSTEMS WILL ALSO MOVE
EWD WITH THE COLD FRONT EVENTUALLY MERGING/OVERTAKING THE SURFACE
TROUGH OVER ND AND NWRN MN TONIGHT.
12Z AREA SOUNDINGS SHOW A PRONOUNCED CAP/ELEVATED MIXED LAYER BASED
AROUND 900-850 MB...WITH NEAR DRY ADIABATIC LAPSE RATES EXTENDING
FROM THE INVERSION INTO THE MID LEVELS. ELEVATED CONVECTION HAS
BEEN MOVING EWD ACROSS WRN/CENTRAL ND THIS MORNING...BUT IT APPEARS
THAT SURFACE TEMPERATURES WILL NEED TO REACH 95-100F IN ORDER TO
ELIMINATE THE CAP THROUGH DIABATIC HEATING PROCESSES. MODEL
GUIDANCE INDICATES THAT A WEAKENING CAP IS LIKELY TO PERSIST THROUGH
THE AFTERNOON /ESPECIALLY GIVEN THE CLOUD COVER MOVING EWD ACROSS
ND/ WITH A LOW PROBABILITY OF SURFACE-BASED CONVECTION DEVELOPING.
LOW LEVEL CONVERGENCE MAY INCREASE THIS EVENING ACROSS NERN ND/NWRN
MN AS THE COLD FRONT MOVES ACROSS THE AREA WHICH MAY INCREASE THE
POTENTIAL FOR ISOLATED SURFACE-BASED THUNDERSTORMS TO DEVELOP. THE
SRN EDGE OF THE STRONGER WESTERLY FLOW ALOFT IS FORECAST TO EXTEND
ACROSS NRN PARTS OF ND AND MN. THIS WILL CONTRIBUTE TO SUFFICIENT
DEEP LAYER SHEAR WHICH WILL ENHANCE THE INTENSITY OF ANY PERSISTENT
UPDRAFTS THAT CAN DEVELOP. STRONGER CELLS WILL HAVE POTENTIAL TO
PRODUCE HAIL AND STRONG WIND GUSTS...BUT WILL MAINTAIN LOW SEVERE
PROBABILITY DUE TO ANTICIPATED LOW COVERAGE OF STORMS.
..SWRN NM INTO CENTRAL/SRN AZ...
12Z SOUNDINGS SHOW INVERTED-V PROFILES IN PLACE WITH A DEEP
SURFACE-BASED MIXED LAYER AND AMPLE MID LEVEL MOISTURE.
HOWEVER...WATER VAPOR IMAGERY INDICATES MID/UPPER LEVEL DRYING
MOVING SWD ACROSS NRN/CENTRAL AZ AND NWRN NM...AND THE PROGRESSION
OF THE DRY INTRUSION MAY LIMIT THE COVERAGE OF STORMS DEVELOPING
OVER THE HIGHER TERRAIN OF CENTRAL AZ INTO NWRN NM. ISOLATED STRONG
STORMS WILL STILL BE POSSIBLE...ESPECIALLY ALONG AND SOUTH OF THE
WATER VAPOR MOISTURE DISCONTINUITY...AND THERMODYNAMIC PROFILES
INDICATE POTENTIAL FOR WET MICROBURSTS TO DEVELOP. WEAK WINDS ALOFT
SUGGEST PULSE STORMS ARE MOST LIKELY TO DEVELOP WITH MINIMAL STORM
PROPAGATION WHICH WILL LIMIT OVERALL SEVERE THREAT.
.WEISS/JEWELL.. 09/01/2007
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