208 
FXUS63 KOAX 041928
AFDOMA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
230 PM CDT FRI JUN 4 2004

.DISCUSSION...
MAIN FORECAST CHALLENGE WILL BE TIMING OF PRECIPITATION LATE 
TONIGHT...AND HOW HARD TO HIT THE POPS ON SATURDAY...AND POTENTIAL 
STRENGTH OF THUNDERSTORMS ONCE THEY DEVELOP.

LATEST SURFACE ANALYSIS HAD A RIDGE OF HIGH PRESSURE TO OUR EAST 
WITH ORGANIZING LOW PRESSURE ALONG THE FRONT RANGE OF THE ROCKIES. 
UPPER AIR ANALYSIS FROM 12Z THIS MORNING INDICATED A WEAK AREA OF 20 
METER HEIGHT FALLS JUST WEST OF THE CONTINENTAL DIVIDE...WHICH WAS 
BEGINNING TO KICK OFF SCATTERED THUNDERSTORMS THROUGHOUT THE 
INTERMOUNTAINEOUS REGION THROUGH MID AFTERNOON. 

MODEL GUIDANCE REMAINS SIMILAR...PUSHING THE TROUGH OF LOW PRESSURE 
ONTO THE PLAINS. DEVELOPING MCS SHOULD PUSH THROUGH CENTRAL 
NEBRASKA...POSSIBLY MOVING INTO WESTERN PORTIONS OF THE WARNING AREA 
MAINLY AFTER MIDNIGHT. THE UPPER TROUGH CONTINUES TO SHARPEN THROUGH 
THIS TIME AS LOW LEVEL MOISTURE CONTINUES TO ADVECT NORTHWARD ON 
MODEST 850 FLOW. UPPER VERTICAL VELOCITIES WILL BE MAXIMIZED ACROSS 
THE REGION THROUGH THE DAYTIME HOURS ON SATURDAY...THUS HAVE DECIDED 
TO BUMP THE POPS UP INTO THE LIKELY CATEGORY...RANGING FROM 60 TO 70 
PERCENT BY AFTERNOON FOR MOST AREAS. STILL IN A SLIGHT RISK OF 
SEVERE THUNDERSTORMS ON THE DAY 2 OUTLOOK...HOWEVER IT APPEARS TO BE 
A MARGINAL RISK AS BULK SHEAR VALUES REMAIN ON THE LOW END AROUND 30 
KNOTS OR SO. INCREASED MOISTURE AND CLOUDINESS SHOULD ALSO INHIBIT 
WIDESPREAD HEATING...THUS INSTABILITY WILL BE MARGINAL ALSO. 
OVERALL...STEEP LAPSE RATES IN THE 1000/850 LAYER WILL EXIST...BUT 
NOT IMPRESSIVE IN THE 850/700 OR 700/500 MB LAYERS. PW VALUES DO 
INCREASE TO 1.5 TO 1.7 INCHES...THUS FEEL THERE IS THE CHANCE OF 
HEAVY RAIN WHEN THUNDERSTORMS DO DEVELOP...BUT OVERALL WE MAY BE 
ABLE TO BREAK OUR STREAK OF SATURDAY SEVERE WEATHER OUTBREAKS.

IT APPEARS THAT FLOW WILL REMAIN PROGRESSIVE...THUS ANY LINGERING 
PRECIPITATION SHOULD END FROM WEST TO EAST BEFORE MIDNIGHT SATURDAY 
EVENING...WITH HIGH PRESSURE BUILDING BACK INTO THE REGION FOR 
SUNDAY AND FOR THE FIRST PART OF NEXT WEEK.

IN THE EXTENDED...RETURN FLOW DEVELOPS RATHER QUICKLY WITH HEAT 
RETURNING TO THE CENTRAL PLAINS. WITH INCREASING SOUTHERLY FLOW 
THROUGH THE WEEK...HAVE STEADILY WARMED TEMPERATURES EACH DAY 
THROUGH ABOUT WEDNESDAY...THEN ANOTHER CHANCE OF SHOWERS AND 
THUNDERSTORMS AS THE NEXT AREA OF LOW PRESSURE MOVES THROUGH. BY 
TUESDAY...WE MAY SEE HIGHS AT OR JUST ABOVE 90...COOLING BACK DOWN 
INTO THE UPPER 70S TO LOWER 80S BY FRIDAY.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.

&&

NOTE...EFFECTIVE 1200 UTC JUNE 8TH THE AWIPS PRODUCT IDENTIFIER
/PID/ FOR THE AREA FORECAST DISCUSSION ISSUED BY OMAHA WFO WILL
CHANGE TO OMAAFDOAX.  THE WMO CODE WILL REMAIN FXUS63 KOAX.

$$

DEWALD