MESO: Mesoscale Discussion 1456

ACUS11 KWNS 122215
SWOMCD
SPC MCD 122215
MNZ000-NDZ000-122315-

MESOSCALE DISCUSSION 1456
NWS STORM PREDICTION CENTER NORMAN OK
0515 PM CDT THU JUL 12 2012

AREAS AFFECTED...FAR ERN ND AND ADJACENT FAR NWRN MN

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 122215Z - 122315Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THE POTENTIAL IS LOW FOR AN ISOLATED TORNADO DURING THE
REMAINDER OF THE AFTERNOON INTO THE EARLY EVENING ACROSS FAR ERN ND
INTO ADJACENT COUNTIES OF NWRN MN. TSTMS WILL ALSO REMAIN POSSIBLE
INTO CENTRAL ND...BUT THE SEVERE WEATHER THREAT SHOULD BE QUITE LOW.

DISCUSSION...ALTHOUGH REGIONAL RADAR IMAGERY/LIGHTNING DATA SHOWED
AN INCREASE IN TSTM COVERAGE IN FAR ERN/NERN ND SINCE 21Z GIVEN A
MOIST/MODERATELY UNSTABLE ENVIRONMENT...THE POTENTIAL FOR SEVERE
STORMS...INCLUDING AN ISOLATED TORNADO THREAT...IS EXPECTED TO
REMAIN LOW LATE THIS AFTERNOON AND EARLY EVENING. 21Z MESOANALYSIS
SHOWED A PERSISTENT AREA OF LOW PRESSURE IN NERN ND AND A SECOND LOW
OVER NERN SD...WITH THE TSTM ACTIVITY DEVELOPING ALONG A SURFACE
TROUGH EXTENDING SWD THROUGH FAR ERN ND. WEAK DEEP LAYER SHEAR IS
NOT CONDUCIVE FOR SUPERCELLS AND 15-20 KT WSWLY MEAN FLOW HAS
RESULTED IN STORMS MOVING E/NEWD OFF THE SURFACE BOUNDARY. DESPITE
FAVORABLE SURFACE VORTICITY ALONG THE N-S ORIENTED TROUGH AND
SUFFICIENT SFC-3 KM CAPE FOR NON-MESOCYCLONE TORNADO
DEVELOPMENT...THE FACT THAT STORMS ARE NOT REMAINING ON THE BOUNDARY
IS GREATLY REDUCING THE THREAT FOR ISOLATED TORNADOES.

FARTHER W/NW INTO CENTRAL PARTS OF ND...A FEW STORMS HAVE DEVELOPED
INVOF ANOTHER SURFACE TROUGH TRAILING SW TO W THEN NW THROUGH
CENTRAL/NORTH CENTRAL ND. WEAK INSTABILITY/SHEAR PARAMETER SPACE
SUGGESTS THIS ACTIVITY WILL HAVE A DIFFICULT TIME TO BECOME
SUSTAINED AND PRODUCE A SEVERE WEATHER THREAT. TSTMS WILL REMAIN
POSSIBLE AS ASCENT ALONG THE SRN EXTENT OF A VORT LOBE MOVES ACROSS
NORTH CENTRAL/CENTRAL ND INTO THE EVENING.

..PETERS/THOMPSON.. 07/12/2012

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

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

LAT...LON 48749715 47709666 46579695 46409782 46569953 46920037
47470097 48060080 48280044 47579937 47629812 48089761
48489776 48749715

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