Severe Thunderstorm Warning 23, NWS Pueblo, CO

SOUTH CENTRAL AND SOUTHEAST COLORADO AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO
218 PM MDT SUN MAY 30 1999

TIMING OF MID-LEVEL SHORTWAVES AND SURFACE FRONTAL POSITION OVER NEXT
TWO DAYS THE MAIN CHALLENGE THIS FORECAST PACKAGE.

TONIGHT/MEMORIAL DAY: CURRENT WATER VAPOR IMAGERY SHOWED WEAK SHEAR
AXIS MOVING THROUGH CENTRAL CO AT THE MOMENT.  HARD TO PICK OUT
SIGNIFICANT SHORTWAVES ACROSS SOUTHWESTERN U.S. AS HAS BEEN THE CASE
THE LAST FEW DAYS. LIGHTNING DATA INDICATING THE MAIN SHRA/TSRA
ACTION IS JUST AHEAD OF SHORTWAVE IN NORTHEASTERN CO.  THERE ARE A
FEW STRIKES FROM TIME TO TIME ACROSS WESTERN HALF OF CWA AT THE
MOMENT. DRYLINE HAS MADE ITS CLIMATOLOGICAL JUMP EASTWARD INTO
WESTERN KS WITH A FRONTAL BOUNDARY EXTENDING FROM THE NORTHERN
PLAINS INTO SOUTHEASTERN WY TO LOW IN WEST CENTRAL WY PER 19Z/30
SURFACE ANALYSIS.  SURFACE WIND DISORGANIZED ACROSS CWA. CONVECTIVELY
INDUCED PRECIPITATION NOT AS WIDESPREAD AS YESTERDAY WITH ONLY
ISOLATED TO WIDELY SCATTERED COVERAGE ACROSS THE EASTERN SAN JUAN AND
LA GARITA MOUNTAINS AND UPPER AR RIVER VALLEY.  NOT MUCH IN THE WAY
OF STRONG CU VERTICAL DEVELOPMENT IN SOUTHEASTERN CO PLAINS YET PER
IR SATELLITE AND LOOK OUTSIDE DUE TO LACK OF GOOD FOCI FOR
INITIATION. LAPS CAPES RUNNING ABOUT 1400-1600 J/KG WHICH IS QUITE
LESS THAN YESTERDAY.  SHORT RANGE MODELS ARE FAIRLY CONGRUENT WITH
TIMING/ POSITION OF POSITIVELY TILTED ID SHORTWAVE OVER THE NEXT 12-
24 HOURS. WILL LOOK FOR PROGRESSIVE WAVE TO SLOWLY MIGRATE INTO WY BY
MONDAY AFTERNOON. BIG KEY TO THE FORECAST WILL BE SURFACE FRONTAL
POSITION TONIGHT/MEMORIAL DAY.  PLAN TO FOLLOW ETA GIVEN BETTER
TOPOGRAPHIC RESOLUTION.  SCATTERED SHRA/TSRA ACROSS WY/NORTHEASTERN
CO WILL LIKELY TRANSITION TO A MCS LATER ON TONIGHT. MCS...AT EXIT
REGION OF LLJ ACROSS CENTRAL PLAINS...WILL MIGRATE EAST SOUTHEASTWARD
TOWARDS BETTER LOW LEVEL MOISTURE/LIFT SOURCE TONIGHT/MEMORIAL DAY.
MCS COULD HELP DRIVE SURFACE BOUNDARY TO ETA POSITION ACROSS CWA BY
MONDAY AFTERNOON. WILL NEED TO MAINTAIN A SMALL POP OR AREAL COVERAGE
UNTIL SUNSET.  MAY NOT PUT A TIMER ON PRECIPITATION IN EASTERN CWA
FOR FEAR OF ANY MCS OUTFLOW BOUNDARIES. WILL CONTINUE LOW POPS FOR
MEMORIAL DAY WITH FRONT ACROSS CWA. CURRENT ZFP POPS AND TEMPS LOOK
GOOD...SO WILL CONTINUE.

MONDAY NIGHT/TUESDAY: ALL KINDS OF TIMING AND RUN-TO-RUN PROBLEMS
WITH SHORT RANGE MODELS HANDLING OF PROGRESSIVE OPEN MID-LEVEL
SHORTWAVE MOVING THROUGH ROCKIES MONDAY NIGHT AND TUESDAY. ETA IS THE
FASTEST...WHILE AVN LAGS SYSTEM BY 12 HOURS.  NGM IS MIDDLE OF ROAD.
WITH THE LACK OF ANY STRONG RIDGING ACROSS MID-SECTION OF THE
COUNTRY...WOULD TEND TO LEAN TOWARDS ETA SOLUTION FOR NOW.  SO...WILL
LOOK FOR MID-LEVEL SHORTWAVE TO BE OUT OF THE AREA BY MONDAY NIGHT.
HOWEVER...LOW LEVEL EAST-SOUTHEASTERLY RETURN FLOW AND DAYTIME
HEATING WOULD CONTINUE THE THREAT OF ANY UPSLOPE/DIURNAL CONVECTIVELY
INDUCED PRECIPITATION. CURRENT EXTENDED(TUE) HAS MENTION OF SHRA/TSRA
...SO WILL MAINTAIN GIVEN UNCERTAINTY AND PREVENT YO-YO FORECASTING.
NOT EXPECTING A SIGNIFICANT CHANCE IN TEMPS FOR MONDAY
NIGHT/TUESDAY.

EXTENDED: EXTENDED MODEL RUNS CONTINUE TO INDICATE...WITH SOME RUN-
TO-RUN AND MODEL-TO-MODEL SPATIAL AND TEMPORAL DIFFERENCES...OF AN
ATYPICAL EARLY JUNE SYNOPTIC SCALE FLOW PATTERN ACROSS CONTIGUOUS
48 STATES.  ANOTHER DEEP LONGWAVE TROUGH IN THE WESTERN U.S.
COMBINED WITH STRONG RIDGING IN THE MS RIVER VALLEY WILL ALLOW FOR
STRONG SOUTHWESTERLY FLOW TO RETURN TO CO.  AS IN THE PAST FEW
DAYS...THE FORECAST PROBLEM WILL BE THE TIMING OF WEAK MID-LEVEL
SHORTWAVES EJECTING FROM LONGWAVE TROUGH OVER THE WESTERN U.S.
EXTENDED ALREADY HAS PRECIPITATION MENTIONED FOR WED/THU AND WILL
MAINTAIN.  HOWEVER...THERE IS SOME INDICATION OF DRY SLOT WORKING
INTO SOUTHEASTERN CO BY FRI...SO WILL NOT GO WITH POP GENERALLY ALONG
AND EAST OF I-25.  STILL COULD NOT RULE OUT SOME DIURNAL SHRA/TSRA IN
MOUNTAINS. THEREFORE...WILL ADD CHANCE OF FOR MOUNTAIN ZONES.

.PUB...NONE.

METZE