FXUS63 KOAX 040751
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
251 AM CDT SAT JUN 4 2011
.DISCUSSION...
THUNDERSTORM CHANCES THROUGH SUNDAY NIGHT ARE THE MAIN FORECAST
CONCERNS. WARM TEMPERATURES TO FOLLOW NEXT WEEK.
STORMS FIRED WESTERN NEBRASKA LATE FRIDAY EVENING AND RACED EAST
NORTHEAST THROUGH OUR NORTHERN CWA EARLY SATURDAY MORNING. RIGHT
ENTRANCE REGION OF 110KT 300MB JET PROVIDED LIFT OVER STALLED
FRONTAL BOUNDARY ACROSS OUR CWA...WITH LOW LEVEL JET OF 40 TO 50 KTS
FROM KANSAS INTO SOUTHEAST NEBRASKA INCREASING IN RESPONSE TO UPPER
DIFFLUENCE. MORE STORMS WERE FIRING ACROSS WESTERN AND CENTRAL
NEBRASKA AS A RESULT OF LOW LEVEL THETA-E ADVECTION. THESE STORMS
COULD CONTINUE TO SPREAD/DEVELOP EAST THIS MORNING...BUT
INSTABILITY/MOISTURE IS LACKING IN NORTHEAST NEBRASKA. WILL MAINTAIN
AT LEAST MENTION OF SHOWERS OR STORMS THIS MORNING...HOWEVER
COVERAGE/INTENSITY TRENDS SHOULD BE DOWNWARD.
FOCUS SHOULD THEN TURN TO FRONTAL BOUNDARY ACROSS SOUTHEAST NEBRASKA
AND SOUTHWEST IOWA. MORNING CONVECTION COULD NUDGE BOUNDARY FARTHER
SOUTH...BUT LIKELY WILL REMAIN IN OUR SOUTHERN CWA. SURFACE DEW
POINTS IN THE MID TO UPPER 60S THERE WILL REMAIN IN PLACE AS
TEMPERATURES CLIMB TOWARD 90. RELATIVELY WARM MID LEVEL TEMPERATURES
(10C AT 700MB) WILL INHIBIT CONVECTION MUCH OF THE AFTERNOON...BUT
SURFACE BASED CAPES OF 3000 J/KG WILL EVENTUALLY BE REALIZED AS CAP
ERODES BEFORE 00Z. NEARLY UNIDIRECTIONAL FLOW ALOFT WILL PRODUCE
WESTERLY 0-6KM BULK SHEAR VECTORS AT 25-30KTS...INTERSECTING FRONTAL
BOUNDARY AT A PRETTY SHALLOW ANGLE. THIS COMBINATION SUGGESTS MORE
OF A LINEAR CONFIGURATION OF STORM CLUSTERS WITH WIND A THREAT. SOME
HAIL POTENTIAL AS WELL GIVEN STRONG INSTABILITY ESPECIALLY
INITIALLY. TORNADO THREAT IS MINIMAL BUT NOT ZERO...ESPECIALLY IN
FRONTAL ZONE WHERE LOW LEVEL SHEAR/HELICITY IS MAXIMIZED.
STORMS SHOULD MOVE EAST WITH A GRADUAL SHIFT TO THE NORTH OVERNIGHT
AS FRONT BEGINS TO LIFT THROUGH EASTERN NEBRASKA. AGAIN LINGERING
STORMS ARE POSSIBLE SUNDAY MORNING...BUT REGENERATION ALONG FRONT IS
MORE LIKELY IN THE AFTERNOON. GFS SUGGESTS FRONT WILL LIE ACROSS OUR
NORTHERN CWA SUNDAY AFTERNOON WITH POOLING LOW LEVEL DEW POINTS
BOOSTING CAPES TOWARD 3000 J/KG AGAIN. GFS SHOWS BULK SHEAR A BIT
STRONGER SUNDAY AFTERNOON...BUT LOW LEVEL CONVERGENCE IS WEAKER. AND
THERE IS SOME QUESTION OF WHERE FRONTAL BOUNDARY WILL BE WHEN STORMS
FIRE. WILL MAINTAIN A SMALL CHANCE IN OUR NORTH SUNDAY AND SUNDAY
EVENING BEFORE FRONT LIFTS OUT OF THE AREA.
WARMING MID LEVEL TEMPERATURES SHOULD SQUELCH CONVECTION MONDAY AND
TUESDAY. SURFACE TEMPERATURES WILL LIKELY REACH THE MIDDLE 90S IN
MANY AREAS AS WELL. UPPER TROUGH ALONG THE WEST COAST WILL THEN
BEGIN TO EJECT IMPULSES THROUGH THE ROCKIES AND INTO THE NORTHERN
PLAINS...EFFECTIVELY KNOCKING DOWN RIDGING IN THE PLAINS AND
ALLOWING STORM TRACK TO MOVE CLOSER TO OUR CWA. A WEAK FRONTAL
BOUNDARY IS ADVERTISED TO MOVE INTO THE REGION BY WEDNESDAY
EVENING...THUS WILL INCREASE THUNDERSTORM CHANCES THEN. THAT FRONT
HAS NOWHERE TO GO AS SOUTHWESTERLY FLOW ALOFT PARALLELS
BOUNDARY...SO CONTINUED CHANCES FOR CONVECTION LOOK LIKELY RIGHT
THROUGH THE END OF THE WEEK.
DERGAN
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
ISOLATED TSRA OVER CNTRL AND NERN NEB WERE MIGRATING NORTHEAST ALONG
NORTH SIDE OF STAGNANT SFC BNDRY EXTENDING FM NERN IA TO WRN KS.
EXPECT THE ISOLATED ACTIVITY TO COME TO A CONCLUSION TWD 12Z THIS
MORNING. OTHERWISE...HAVE LATEST SET OF TAFS AT VFR COND.
HOWEVER...AFOREMENTIONED SFC BNDRY WILL SLIP A BIT FARTHER SOUTH
TODAY AND HANG UP ALONG THE NEB/KS BORDER AROUND 05/00Z...LEADING TO
POSSIBLE TSRA DEVELOPMENT. UNSURE OF AREAL COVERAGE SO DID NOT
INCLUDED IN CURRENT TAFS...BUT WILL RE-EVALUATE AT 04/12Z ISSUANCE.
DEE
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$