Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 051757
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1257 PM CDT TUE MAY 5 2015

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 333 AM CDT TUE MAY 5 2015

ACTIVE WEATHER PATTERN CONTINUES ACROSS THE PLAINS THIS WEEK WITH
EPISODIC PERIODS OF SEVERE WEATHER/CHANCES FOR RAIN.

THE 00Z H3 JET WAS STRONGEST OVER THE PACIFIC NORTHWEST AND ACROSS
MEXICO.  THE H5 PATTERN HAD CLOSED LOW PRESSURE OFF THE PACIFIC
NORTHWEST AND ANOTHER AREA OF CLOSED LOW PRESSURE OVER THE
SOUTHWEST U.S. AHEAD OF THE SOUTHWEST SYSTEM...INTO THE PLAINS
THERE WERE WEAK RIPPLES OF EMBEDDED SHORTWAVE TROFS IN THE FLOW.
H85 FLOW WAS NOT REAL STRONG...25 TO 30KTS ACROSS PARTS OF
KANSAS/OKLAHOMA/TEXAS...WITH POOLING OF MOISTURE +10-12DEG C FROM
KANSAS. THE OAX SOUNDING WAS +10 AT H85 AND WITH 1.30 INCHES
PWAT...NEARLY 200% NORMAL. THE SURFACE FRONT EARLY THIS MORNING
WAS LOCATED OVER SOUTHEAST NEBRASKA AND SOUTHERN IOWA...WITH
ANOTHER BOUNDARY SOUTH OVER CENTRAL KANSAS.

WARM FRONT WAS MAKING STEADY PROGRESS NORTHWARD EARLY THIS
MORNING...AND HAD MOVED NORTH OF A LINCOLN TO RED OAK LINE AS OF 3AM.
ISENTROPIC UPGLIDE OVER FRONTAL ZONE CONTINUED TO GENERATE
SCATTERED SHOWERS ABOUT 40 MILES NORTH OF THE FRONT...AND EXPECT
THIS TREND TO PERSIST DURING THE MORNING AS BOUNDARY LIFTS INTO
NORTHEAST NEBRASKA. IN ITS WAKE...JUICY ATMOSPHERE WILL REMAIN IN
PLACE GIVE RELATIVELY HIGH PRECIPITABLE WATER VALUES AND SURFACE
DEW POINTS APPROACHING 60F...BUT UPPER SUPPORT WILL WANE AS WEAK
WAVE CURRENTLY OVER EASTERN NEBRASKA LIFTS NORTHEAST. WHILE WE
WAIT FOR BETTER UPPER SUPPORT LATER TONIGHT...CAN NOT RULE OUT
ISOLATED TO SCATTERED SHOWERS DEVELOPING IN THE HEAT OF THE
AFTERNOON. SHORT RANGE MESOSCALE MODELS ARE HINTING AT THIS
SCENARIO WITH SURFACE- BASED CAPES REACHING THE 500-1000 J/KG
RANGE IF TEMPERATURES REACH THE MID AND UPPER 70S AS EXPECTED.
THIS SHOULD BE ACHIEVABLE IF BREAKS IN CLOUDS ARE
REALIZED...ESPECIALLY IN SOUTHEAST NEBRASKA AND SOUTHWEST
IOWA...AS PER A MAJORITY OF SHORT RANGE MODEL FORECASTS.

TONIGHT...THE CLOSED LOW OVER THE SOUTHWEST U.S. WILL LIFT ACROSS
COLORADO AND BY 12Z...STRETCHES FROM WYOMING TO NORTHEAST
COLORADO...INTO CENTRAL KANSAS. THE 30 TO 35KT JET OVER CENTRAL
KANSAS AND OKLAHOMA INCREASES TO 45 TO 50KTS BY 06Z.  THE SURFACE
FRONT SHOULD BE IN NORTHEAST NEBRASKA...LIFTING NORTH OF THE AREA BY
12Z.  THIS PATTERN WILL PROMOTE SHOWERS AND THUNDERSTORMS OVER THE
WESTERN PLAINS...SHIFTING EASTWARD OVERNIGHT AS THE LOW LEVEL JET
VEERS AND STRENGTHENS. WEDNESDAY MORNING...SHOWERS AND
THUNDERSTORMS WILL CONTINUE ACROSS THE AREAS...SHIFTING INTO
IOWA. DURING THE AFTERNOON...DESTABILIZATION WILL OCCUR FROM
OKLAHOMA NORTH INTO KANSAS AND CENTRAL NEBRASKA ALONG WITH
INCREASING 0-6KM BULK SHEAR OVER KANSAS. THIS COMBINED WITH AN H7
SPEED MAX/H5 SUPPORT IS LIKELY WHY THERE IS A SLIGHT RISK FOR
SEVERE STORMS IN THIS REGION.

THURSDAY...AS THE H5 TROF SLOWLY LIFTS NORTH...BUT GENERALLY
LINGERS OVER THE NORTHERN PLAINS WITH A COLD FRONT OVER THE
CWA...WITH PLENTY OF MOISTURE AHEAD OF THE FRONT...MODERATE
INSTABILITY DEVELOPS WITH 35KTS OF 0-6KM BULK SHEAR. SHOWERS AND
THUNDERSTORMS SHOULD STRENGTHEN WITH AFTERNOON HEATING. CURRENTLY
IN THE MARGINAL SEVERE RISK...BUT MAY SEE THIS INCREASE DUE TO
HIGHER INSTABILITY.

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 333 AM CDT TUE MAY 5 2015

WITH CLOSED H5 LOW PRESSURE OVER CALIFORNIA/NEVADA AND SOUTHWEST
FLOW ALOFT...MOISTURE REMAINS IN PLACE OVER THE CENTRAL AND
SOUTHERN PLAINS. THIS SYSTEM LIFTS NORTHEAST INTO COLORADO
SATURDAY NIGHT AND SUNDAY. THERE WILL BE SHOWERS AND THUNDERSTORM
CHANCES ESPECIALLY ACROSS THE SOUTHERN PART OF THE FORECAST AREA
CLOSER TO THE SURFACE FRONT. STORMS BECOME LIKELY ACROSS THE
ENTIRE FORECAST AREA SATURDAY NIGHT WITH THE PROGRESS OF THE MID
TROPOSPHERIC TROF. THERE AREA SOME TIMING DIFFERENCES SUNDAY
THROUGH MONDAY AS TO HOW LONG THE PRECIPITATION WILL LINGER.
TEMPERATURES SHOULD BE BELOW OR NEAR NORMAL.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1243 PM CDT TUE MAY 5 2015

COMPLEX AVIATION FORECAST THIS AFTERNOON WITH VARIABLE CEILINGS
AND VISIBILITIES THIS AFTERNOON. CONGESTED CU FIELD HAS DEVELOPED
WITH AFTERNOON HEATING CREATING A FEW SCATTERED
SHOWERS...GENERALLY ALONG AND NORTH OF A WARM FRONT DRAPED ACROSS
THE REGION. LOW VISIBILITIES AT KOFK MAY COME BACK OVERNIGHT AND
SO DID HINT AT THIS IN THE TAF. IN ADDITION...SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS WILL LIKELY SPREAD EAST INTO THE AREA
OVERNIGHT AND BECOME WIDESPREAD BY MORNING.

&&

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

$$

SHORT TERM...DERGAN/ZAPOTOCNY
LONG TERM...ZAPOTOCNY
AVIATION...KERN



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