Severe Thunderstorm Warning 12, NWS Salt Lake City, UT

UTAH AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UTAH
240 PM MDT TUE MAY 25 1999

UPPER LOW APPROACHING AZ/NEW MEX BORDER PRODUCING PLENTY OF
CONVECTION IN AND AROUND THE 4-CORNERS REGION THIS AFTERNOON.
WATER VAPOR IMAGERY SUGGESTS LOW MAY BE IN THE EARLY STAGES OF
FILLING...MUCH AS INDICATE BY THE 12Z MODEL RUNS.  SW-NE UPPER
RIDGE AXIS WILL DRIFT INTO THE INTERMOUNTAINS REGION WEDNESDAY...
THEN FORM THE HIGH CENTER OVER THE DESERT SW FOR THE BALANCE OF THE
WEEK.

CONVECTION OVER NRN UTAH BY AND LARGE HAS FAILED TO GENERATE THE
AREAL COVERAGE EXPECTED THIS AFTERNOON.  THIS MAY BE IN A LARGE
PART DUE TO MORE COOLING IN AND AROUND THE 700 MB LEVEL THAN
PREVIOUSLY THOUGHT.  MORE INSTABILITY DOES EXIST TO THE NORTH OF
UTAH...AND AS A RESULT DIURNALLY DRIVEN MOUNTAIN CONVECTION HAS FIRED
UP OVER WRN WY/ERN ID.  EXPECT THAT THIS ACTIVITY WILL PROPAGATE
SOUTHWARD FOR AWHILE...THEN DIE OFF AROUND MIDEVENING WITH THE LOSS
OF HEATING AND/OR AS IT MOVES INTO MORE STABLE AIR.

DIURNAL CONVECTION MAY ACTUALLY HAVE A BETTER RUN OVER THE
MOUNTAINS WEDNESDAY/THURSDAY AS THE UPPER HIGH CENTERS OVER THE
REGION.  THE WEAK FLOW ALOFT ISNT GOING TO PUSH TOO MUCH MOISTURE
OUT OF THE AREA...AND THE MIDLEVEL TEMPS ARENT PROGGED TO INCREASE
MUCH EVEN AS THE LOWER LEVELS WARM.

MOST RECENT MEDIUM RANGE GUIDANCE APPEARS MORE IN CONSENSUS WITH
AMPLIFYING RIDGE OVER THE ERN PACIFIC EARLY IN THE WEEKEND LEADING
TO A CLOSED LOW FORMING WEST OF UTAH BY EARLY SUNDAY.  THE ECMWF...
AND TO SOME EXTENT THE MRF...SHOW A RATHER DOMINATE RIDGE IN THE
ERN PACIFIC.  THIS WOULD SUGGEST THAT THE LOW MAY PARK OR EVEN DRIFT
FURTHER SOUTH HEADING INTO MEMORIAL DAY.  THE NOGAPS IN CONTRAST
WOULD HAVE THIS LOW MOVE RIGHT OVER UTAH LATE SUNDAY/MEMORIAL DAY
BRINGING A COOL WET HOLIDAY.  JURY IS STILL OUT ON MEMORIAL DAY...
BUT DO SEE A WEAK COLD FRONT MOVING THROUGH UTAH LATE SATURDAY
/SUNDAY WITH NOTICEABLY COOLER TEMPS AND ISOLATED-SCATTERED PCPN
POSSIBLE.  MOST OF THE PCPN WILL BE IN VICINITY OF THE LOW...SO STILL
HOPING THAT THE LOW REMAINS WEST FOR THE HOLIDAY WEEKEND.

SLC 3333  CDC 3333  CONGER

.SLC...FLOOD WATCH FOR THE LOGAN RIVER UFN UTZ001-007.