MESO: Mesoscale Discussion 1578

ACUS11 KWNS 252207
SWOMCD
SPC MCD 252206
MNZ000-NDZ000-252330-

MESOSCALE DISCUSSION 1578
NWS STORM PREDICTION CENTER NORMAN OK
0506 PM CDT WED JUL 25 2007

AREAS AFFECTED...NERN ND INTO NWRN MN

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 252206Z - 252330Z

STORM INITIATION WILL BECOME INCREASINGLY LIKELY BETWEEN 22-00Z WITH
A THREAT OF LARGE HAIL AND DAMAGING WINDS. SATELLITE/RADAR TRENDS
ARE BEING MONITORED FOR A WW ISSUANCE.

LATEST MESOANALYSIS INDICATES SURFACE LOW NEAR WINNIPEG WITH
ATTENDANT COLD FRONT EXTENDING SWWD TO JUST W OF DVL TO NEAR BIS.
DEEP MOIST CONVECTION HAS RECENTLY BECOME ESTABLISHED NEAR SURFACE
LOW INVOF WINNIPEG WITH A WEAK ECHO DEVELOPING ALONG FRONT IN ERN
TOWNER CO ND AS OF 2145Z. A COUPLE WELL DEFINED HORIZONTAL
CONVECTIVE ROLLS /HCRS/ ARE BEING OBSERVED WITHIN PRE-FRONTAL WARM
SECTOR BETWEEN JMS AND FAR...ONE OF WHICH LIKELY INTERSECTS FRONT
OVER CAVALIER COUNTY IN FAR NERN ND. THESE INTERSECTION POINTS MAY
PROVIDE THE FOCUS FOR STORM DEVELOPMENT IN THE NEXT 1 TO 2 HOURS.

WARM SECTOR AIR MASS HAS BECOME STRONGLY UNSTABLE LATE THIS
AFTERNOON OWING TO THE CO-LOCATION OF A VERY MOIST BOUNDARY LAYER
WITH STEEP LAPSE RATES WITH MLCAPES OF 3000-4000 J/KG. REGIONAL
VWPS SUGGEST THAT THE STRONGER VERTICAL SHEAR RESIDES ACROSS
POST-FRONTAL AIR MASS OVER WRN ND WITH GENERALLY 20 KT OR LESS
THROUGH THE LOWEST 6 KM AGL ACROSS PRIMARY INSTABILITY AXIS.

WHILE OVERALL THERMODYNAMIC PROFILE REMAINS QUITE WARM...THE STEEP
LAPSE RATES AND DEGREE OF CONVECTIVE INSTABILITY SUGGEST THE
POTENTIAL FOR SEVERE HAIL WITH ANY STORMS THAT CAN BECOME
ESTABLISHED. ADDITIONALLY...RUC FORECAST SOUNDINGS INDICATE
RELATIVELY STRONG EVAPORATIVE COOLING/DOWNDRAFT POTENTIAL WITH
DCAPES OF 1000-1500 J/KG. THEREFORE...SOME THREAT WILL ALSO EXIST
FOR DAMAGING WINDS...ESPECIALLY IF STORMS CAN ORGANIZE A COLD POOL.

.MEAD.. 07/25/2007

..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...FGF...BIS...

49009848 49019573 48319598 47669651 47129778 47249903
47839972

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