FXUS63 KOAX 140805
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
305 AM CDT TUE JUN 14 2011
.DISCUSSION...
FORECAST CONCERNS DURING THE PERIOD WILL CONTINUE TO BE
THUNDERSTORMS CHANCES AND TEMPERATURES.
THE UNSETTLED WEATHER PATTERN CONTINUES WITH A STRONG...SOMEWHAT
NEGATIVELY TILTED MID LEVEL TROUGH FROM MONTANA INTO THE ROCKIES
PUSHING EASTWARD ACROSS THE DAKOTAS AND THE CENTRAL PLAINS TODAY AND
INTO IOWA BY WEDNESDAY MORNING. MID LEVEL RIDGING MOVES IN FOR ABOUT
24 HOURS (TUESDAY NIGHT INTO WEDNESDAY EVENING)...THEN A LARGE
CLOSED LOW OVER MONTANA BEGINS TO INFLUENCE OUR WEATHER AGAIN WITH
RAIN CHANCES THURSDAY THROUGH THE EXTENDED.
ALL AREAS IN THE MISSOURI RIVER BASIN ARE EXTREMELY SENSITIVE TO
HEAVY RAIN. THIS PATTERN BY IT/S NATURE HAS A HIGHER CONFIDENCE OF
THOSE HEAVIERS RAINS IN MONTANA AND NORTH DAKOTA...CLOSER TO THE MID
LEVEL LOW. FOR OUR AREA...WE WILL SEE STORMS CAPABLE OF PRODUCING
HEAVY RAIN...HOWEVER THE LOCATION OF THEM WILL BE MUCH MORE
DIFFICULT TO PINPOINT DUE TO THE TRANSIENT NATURE OF THE FORCING FOR
THOSE STORMS.
THE 00Z OAX SOUNDING SHOWED A LOT OF MOISTURE UP TO H750MB WITH 1.41
INCHES OF PRECIPITABLE WATER. THE LOW LEVELS WERE STABLE...HOWEVER
MID LEVEL LAPSE RATES WERE STEEP...AROUND 8 DEG C/KM. A LOOK AT THE
MID LEVEL PATTERN HAD A MID LEVEL RIDGE OVER TEXAS...AND WAVY MID
LEVEL TROUGHING WESTERN MONTANA INTO UTAH AND ARIZONA INTO THE
CENTRAL AND NORTHERN PLAINS. CONVECTIVE CLUSTERS OF THUNDERSTORMS
WERE NOTED IN OVER THE NORTHERN AND CENTRAL ROCKIES INTO THE WESTERN
PLAINS AND ALSO MOVING INTO CENTRAL ILLINOIS. ONE AREA OF
THUNDERSTORMS HAS HELD TOGETHER AND PUSHED INTO NORTHEAST KANSAS.
ANOTHER HAS BUILD BACKWORD INTO NORTHER NEBRASKA AND WEST CENTRAL
IOWA. THESE AREAS HAVE GENERAL BEEN OUTSIDE OF THE WARM MID LEVEL
TEMPERATURES. SURFACE LOW PRESSURE WAS OVER THE OKLAHOMA
PANHANDLE...WITH THE SURFACE FRONT INTO NORTHEAST KANSAS. WE ARE
TO THE NORTH OF THIS FRONT WITH AN EASTERLY WIND...RESULTING IN
CLOUDS AND LOW TEMPERATURE/DEWPOINT SPREADS. THE HIGH PRECIPITABLE
WATER (1 TO 1.50 INCHES)AXIS REMAINS OVER THE MISSOURI RIVER
VALLEY.
TODAY AND TONIGHT...SHORTWAVE TROF ENERGY WILL MAKES IT/S WAY INTO
THE CENTRAL PLAINS...LINGERING IN THE DAKOTAS TONIGHT...BUT PUSHING
ACROSS IOWA BY WEDNESDAY MORNING. AS MENTIONED...HIGHEST CONFIDENCE
IN THE PRECIPITATION IS CLOSER TO THE UPPER LOW OVER THE
DAKOTAS...AND WITH THE STRONG LOW LEVEL JET FROM EASTERN
KANSAS...SOUTHERN IOWA AND MISSOURI AND ILLINOIS. LOCALLY WE HAVE A
CHANCE FOR THUNDERSTORMS WITH THE MOISTURE AND STEEP MID LEVEL LAPSE
RATES IN PLACE AND AS THE SHORT WAVE TROUGH PROGRESSES ACROSS SOUTH
DAKOTA AND NEBRASKA. ADDITIONALLY...SURFACE LOW PRESSURE WILL MOVE
INTO NORTHEAST KANSAS AND NORTHWEST MISSOURI. BEING ON THE NORTH
SIDE OF THE LOW...WE WILL BE MORE STABLE IN THE LOW LEVELS AND HAVE
WARM MID LEVEL TEMPERATURES OVER ALL BUT THE NORTHERN AND EASTERN
FRINGES OF THE FORECAST AREA. THIS CAP DOES ERODE DURING THE DAY
AND EVENING. THERE IS A SEVERE WEATHER POTENTIAL WITH THE STORMS
THAT FORM TODAY INTO TONIGHT WITH MODERATE INSTABILITY AND
SUFFICIENT DEEP LAYER SHEAR.
BELOW NORMAL TEMPERATURES ARE EXPECTED WITH THE CLOUDS TODAY.
LOCATIONS IN THE SOUTH MAY BREAK OUT SOME WITH HIGHS IN THE 80S..
THE STORMS SHOULD CONTINUE TO PUSH EASTWARD AFTER MIDNIGHT TUESDAY
WITH SUBSIDENCE AND DRIER CONDITIONS MOVING IN. THE DRY WEATHER
WILL CONTINUE WEDNESDAY AND WEDNESDAY EVENING. SURFACE LOW PRESSURE
RE-DEVELOPS OVER THE LEE OF THE ROCKIES AND THE LOW LEVEL JET
STRENGTHENS OVER THE CENTRAL PLAINS WEDNESDAY NIGHT WITH A CHANCE OF
THUNDERSTORMS AGAIN BY EARLY THURSDAY MORNING. SOME CONVECTION MAY
LINGER DURING THE DAY WITH A RENEWED CHANCE FOR MORE STORMS
OVERNIGHT WITH THE NEXT SHORTWAVE TROF.
&&
.AVIATION...
LOW PRESSURE CENTER OVER THE OKLAHOMA PANHANDLE AT 08Z SHOULD TRACK
NORTHEAST INTO NORTHWEST MISSOURI BY 21Z TODAY. CURRENT EASTERLY
WINDS WILL SHIFT TO NORTH OR NORTHWEST. CEILINGS WERE MAINLY BETWEEN
1000 AND 2000 FEET EARLY THIS MORNING BUT SHOULD DROP BELOW 1000
FEET AND REMAIN THERE UNTIL LATE MORNING. VISIBILITIES MAY ALSO DROP
INTO THE 3 TO 5 MILE RANGE. EXPECT CEILINGS TO INCREASE TO MVFR THIS
AFTERNOON BUT COULD DROP BACK TO IFR TONIGHT. THUNDERSTORM ACTIVITY
WILL BE DIFFICULT TO TIME AND GENERALLY LEFT THIS OUT OF THE TAFS
FOR NOW...BUT WILL AMEND AS NEEDED. EXPECT SOME DECREASE IN CLOUD
COVER AFTER 06Z WEDNESDAY WITH VFR CONDITIONS PREVAILING BY 14Z
WEDNESDAY.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
ZAPOTOCNY/MILLER