FXUS63 KOAX 180805
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
305 AM CDT FRI MAR 18 2011
.DISCUSSION...
MAIN CONCERNS CENTER AROUND CHANCES FOR PRECIPITATION THE NEXT
SEVERAL DAYS. THE BEST 12 HOUR PERIODS APPEAR TO BE SATURDAY NIGHT
AND MONDAY NIGHT.
LARGE SCALE PATTERN FEATURES A DECENT TROUGH AT 500 MB OFF THE WEST
COAST OF THE UNITED STATES AND STRONG JETSTREAM LEVEL WINDS FROM
SOUTHERN CALIFORNIA INTO UPPER MICHIGAN. WINDS AT 300 MB WERE THE
STRONGEST (AROUND 140 KNOTS) OVER SOUTH DAKOTA. REGIONAL RADAR
SUMMARIES HAVE SHOWN AN AREA OF ECHOES EXTENDING FROM COLORADO
ACROSS PARTS OF NEBRASKA AND INTO NORTHERN IOWA. THIS APPEARS TO BE
IN ASSOCIATION WITH UPPER LEVEL DIVERGENCE IN THE RIGHT ENTRANCE
REGION OF THE UPPER TROPOSPHERIC JETSTREAK. THERE IS ALSO SOME
FRONTOGENETICAL FORCING IN THE 700-500 MB LAYER. AT THE SURFACE...
HIGH PRESSURE IS OVER MUCH OF THE NORTHERN AND CENTRAL PLAINS. A
NEARLY STATIONARY FRONT CURVED FROM NORTHERN INDIANA INTO THE TEXAS
PANHANDLE...THEN BACK INTO LOW PRESSURE IN SOUTHERN COLORADO. THE
ECHOES OVER THE NORTHERN PART OF THE FORECAST AREA SHOULD PERSIST
THIS MORNING AND GRADUALLY SHIFT SOUTHWARD WITH THE MID LEVEL
MOISTURE AND LIFT. RAINFALL AMOUNTS LOOK TO BE VERY LIGHT WITH THIS
SYSTEM. LEFT THIS AFTERNOON DRY FOR NOW SINCE MID LEVEL DRYING SEEMS
TO TAKE OVER BY AROUND 18Z. BUMPED HIGHS UP JUST A BIT FROM THE
PREVIOUS FORECAST...MOSTLY TO THE MID 50S...CLOSER TO 00Z MODEL
GUIDANCE.
TONIGHT SHOULD BE DRY...WITH LOWS DROPPING INTO THE 30 TO 35 DEGREE
RANGE. EXPECT CLOUDINESS TO INCREASE TOWARD SUNRISE. BOTH THE 00Z
ECMWF MODEL AND THE 00Z GFS MODEL INDICATE A FAIRLY STRONG AREA OF
UPWARD VERTICAL MOTION MOVING ACROSS THE SOUTHERN AND CENTRAL PARTS
OF THE AREA SATURDAY. COMBINATION OF MOISTURE AND LIFT IS BEST OVER
SOUTHEAST NEBRASKA...SO KEPT HIGHEST RAIN CHANCES THERE. 850 MB
MOISTURE SHOULD INCREASE SATURDAY NIGHT...AND THE ATMOSPHERE SHOULD
BECOME MORE UNSTABLE. EXPECT SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS TO DEVELOP OVERNIGHT...WITH SOUTHEAST NEBRASKA AND
SOUTHWEST IOWA THE MOST LIKELY AREAS TO HAVE THUNDER. A FRONTAL
BOUNDARY SHOULD PUSH SOUTH OF THE AREA MONDAY. MODELS ALSO SHOW MID
LEVEL SHORTWAVE RIDGING...SO PRECIPITATION CHANCES WERE LOWERED FOR
ALL AREAS. DID LEAVE SOME LOW PROBABILITIES IN THE SOUTHERN THIRD OF
THE FORECAST AREA. CHANCES SHOULD INCREASE MONDAY NIGHT AS LOW
PRESSURE STRENGTHENS OVER EASTERN COLORADO AND MOVES TOWARD
SOUTHWEST NEBRASKA. 850 MB DEWPOINTS ARE FORECAST TO INCREASE TO
AROUND 10 DEGREES CELSIUS WITH LIFTED INDICES BECOMING NEGATIVE.
RAIN CHANCES WILL LINGER INTO TUESDAY NIGHT...THEN IT SHOULD BE DRY
WEDNESDAY INTO THURSDAY. THE GFS AND ECMWF ARE NOT IN GOOD AGREEMENT
AT THIS POINT IN REGARDS TO FRIDAY OF NEXT WEEK. THE GFS IS WET WITH
THE MID LEVEL FLOW FROM THE SOUTHWEST. THE ECMWF IS DRY...WITH MID
LEVEL FLOW FROM THE NORTHWEST.
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
VFR CONDITIONS ARE EXPECTED AT ALL THREE TAF SITES THROUGH THIS
FORECAST PERIOD WITH MID AND HIGH CLOUDS ACROSS THE REGION. THROUGH
12Z KOFK AND AREAS NORTH COULD EXPERIENCE A FEW SPRINKLES BUT NO
MENTION IN TAF AT THIS TIME. AFTER 12Z SOME VCSH...ESPECIALLY IN
THE KOKF AREA POSSIBLE AND MAY BE ADDED WITH NEXT TAF ISSUANCE.
WINDS AT KOMA AND KLNK WILL SHIFT FROM NORTH TO MORE NORTHEAST...
060-090 AROUND 06KT...AFTER 22Z.
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
DISCUSSION...MILLER
AVIATION...MEYER