Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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000
FXUS63 KOAX 011737
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
1237 PM CDT SAT AUG 1 2015

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 335 AM CDT SAT AUG 1 2015

CHANCE FOR SEVERE THUNDERSTORMS TODAY AND TONIGHT...THEN WARM
TEMPERATURES SUNDAY...ARE THE PRIMARY FORECAST CONCERNS.

CONVECTION TIED TO SOUTHWARD-ADVANCING SURFACE FRONT HAD CLEARED THE
SOUTHERN NEBRASKA AND IOWA BORDERS LATE LAST EVENING. THAT BOUNDARY
IS EXPECTED TO RETREAT NORTHWARD TODAY AS A WARM FRONT IN RESPONSE
TO LOWERING PRESSURES TO OUR NORTHWEST IN ADVANCE OF MID LEVEL
SHORTWAVE DIVING FROM THE NORTHERN ROCKIES INTO SOUTH DAKOTA THIS
AFTERNOON. STRONG MOISTURE ADVECTION WILL FOLLOW WARM FRONT IN
SOUTHERLY LOW LEVEL FLOW...AND WHEN COMBINED WITH POTENT AFTERNOON
HEATING...WILL PRODUCE MOST-UNSTABLE CAPES WELL OVER 2500 J/KG.
ENHANCED NORTHWESTERLY MID LEVEL FLOW ATTENDANT TO APPROACHING
SHORTWAVE WILL INDUCE STRONG 0-6KM BULK SHEAR ON THE ORDER OF 40KT
AS SOUTH TO SOUTHWEST SURFACE FLOW INCREASES. VEERING WIND PROFILES
WITH MAGNITUDE OF SHEAR VECTORS WILL BE SUPPORTIVE OF ROTATING
STORMS SUGGESTING ALL MODES OF SEVERE WILL BE POSSIBLE THIS
AFTERNOON...WITH TORNADO POTENTIAL HIGHEST NEAR WARM FRONT IN
NORTHEAST NEBRASKA AND SOUTHEAST SOUTH DAKOTA...AND ESPECIALLY NEAR
TRIPLE POINT WHERE SOUTHEASTERLY-ADVANCING TROUGH/DRYLINE INTERSECTS
WARM FRONT.

EXPECT STORMS CURRENTLY FIRING IN SOUTH CENTRAL SOUTH DAKOTA INTO
CENTRAL NEBRASKA TO GRADUALLY WORK EAST AND SOUTHEAST THIS
MORNING...WITH ISOLATED TO SCATTERED STORMS REACHING OUR WESTERN
CWA. BETTER CONVECTIVE CHANCES COME THIS AFTERNOON WHEN
INSTABILITY IS MAXIMIZED...WITH FOCUS GEARED TOWARD LOW LEVEL
CONVERGENCE ALONG WARM FRONT...WHICH SHOULD LIE ACROSS NORTHEAST
NEBRASKA INTO WEST CENTRAL IOWA. INCREASING LOW LEVEL JET DURING
THE EVENING WILL SUPPORT CONTINUED DEVELOPMENT OF CONVECTION WITH
PROPAGATION VECTORS SHOWING A SOUTHEAST PROGRESSION ACROSS PARTS
OF EASTERN NEBRASKA AND WESTERN IOWA. EXPECT MOST CONVECTION TO BE
WELL EAST OF WESTERN IOWA BY SUNRISE SUNDAY...BUT SOME LINGERING
INSTABILITY/STORMS ARE POSSIBLE IN THE MORNING IN SOUTHWEST IOWA.

MOST OF SUNDAY IS EXPECTED TO BE DRY AS WESTERLY LOW LEVEL FLOW
PREVAILS ACROSS MUCH OF OUR CWA DURING THE MORNING. HOWEVER LOW
LEVEL MOISTURE WILL TAKE SOME TIME BEFORE BEING SWEPT SOUTH. A COLD
FRONT IS FORECAST TO FOLLOW EXITING SHORTWAVE...REACHING INTERSTATE
80 BY EARLY AFTERNOON THEN CLEARING OUR SOUTHERN BORDER BY LATE
SUNDAY AFTERNOON. WESTERLY WIND COMPONENT POINTS TO TEMPERATURES
WELL INTO THE 90S OVER THE SOUTHERN HALF OF OUR CWA...BUT NORTHERLY
WINDS BEHIND THE FRONT SUGGEST HIGHS CLOSER TO 90 IN OUR NORTH. AND
WITH LOW LEVEL MOISTURE...DEW POINTS IN THE MID 60S...REMAINING OVER
SOUTHEAST NEBRASKA AND SOUTHWEST IOWA SUNDAY AFTERNOON...MUCAPES
WILL AGAIN TOP 2500 J/KG AS FRONT INVADES. THUS WILL INTRODUCE SOME
SMALL THUNDERSTORM CHANCES IN OUR SOUTH THEN.

MONDAY MAY BRING A SIMILAR SCENARIO TO TODAY AS SUNDAY COLD FRONT
STALLS IN NORTHERN KANSAS SUNDAY NIGHT THEN RETREATS BACK NORTH INTO
EASTERN NEBRASKA AND WESTERN IOWA MONDAY. SHORTWAVE IN NORTHWEST
FLOW ALOFT WILL AGAIN LOWER PRESSURES IN THE HIGH PLAINS...INDUCING
SOUTHERLY LOW LEVEL FLOW AND MOISTURE RETURN INTO OUR AREA. WE
SHOULD AGAIN SEE CONVECTION FIRING NEAR AND NORTH OF THE WARM FRONT.
EXACT PLACEMENT OF THAT FRONT WILL NEED TO BE REFINED LATER...BUT
WILL HAVE AT LEAST A SLIGHT CHANCE FOR STORMS OVER MOST OF THE
CWA...WITH HIGHER CHANCES NEAR AND NORTH OF A COLUMBUS TO NEBRASKA
CITY AND CLARINDA LINE. SUFFICIENT INSTABILITY AND SHEAR...30-
40KT...AGAIN SUGGEST SOME SEVERE STORMS WILL BE POSSIBLE.

.LONG TERM...(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 335 AM CDT SAT AUG 1 2015

THERE WILL BE A CHANCE FOR THUNDERSTORMS MUCH OF NEXT WEEK AS
NORTHWEST FLOW ALOFT CONTINUES TO EJECT SHORTWAVES INTO THE NORTHERN
AND CENTRAL PLAINS. THERE IS SOME INDICATION UPPER RIDGE AXIS WILL
SHIFT INTO THE PLAINS FOR A SHORT TIME WEDNESDAY NIGHT...KEEPING
THAT PERIOD DRY...BUT WE QUICKLY GET BACK INTO THE UNSETTLED
NORTHWEST FLOW PATTERN LATE IN THE WEEK.

MONDAY FRONTAL BOUNDARY IS EXPECTED TO REMAIN IN OR NEAR OUR CWA
MONDAY NIGHT INTO TUESDAY BEFORE MORE DEFINED MID LEVEL WAVE SWEEPS
FRONT/MOISTURE TO OUR SOUTHEAST LATER TUESDAY NIGHT OR WEDNESDAY.
GFS SHOWS OUR AREA ON COOL SIDE OF FRONTAL SYSTEM ON TUESDAY...SO
SEVERE THREAT LOOKS MINIMAL. HOWEVER SEVERE POTENTIAL RETURNS BY
THURSDAY AFTERNOON WHEN MAIN STORM TRACK SHIFTS BACK TO THE NORTH
BRINGING LOW LEVEL MOISTURE AND SUPPORTIVE SHEAR PATTERN BACK INTO
OUR AREA.

TEMPERATURES THROUGH THE WEEK LOOK COOLER...AVERAGING THE LOWER 80S
MOST AREAS...AS CLOUDS/PRECIP/THERMAL PROFILE KEEP A LID ON WARMING.

&&

.AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.)
ISSUED AT 1234 PM CDT SAT AUG 1 2015

FOR THIS ISSUANCE...HAVE DECIDED TO REMOVE TEMPO GROUPS FROM TAFS
AS IT APPEARS NOW THAT ANY TSRA ACTIVITY THAT DOES DEVELOP OVER
ERN NEB WILL MOST LIKELY WILL BE ISOLD IN NATURE. THUS VFR
PREVAILING THRU THE FCST PD.

&&

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

$$

SHORT TERM...DERGAN
LONG TERM...DERGAN
AVIATION...DEE


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