FXUS63 KOAX 140901
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
301 AM CST SUN NOV 14 2010
.DISCUSSION...
HANDLING PRECIPITATION CHANCES/TYPES WITH SHORTWAVES MOVING THROUGH
MONDAY AND WEDNESDAY IS THE PRIMARY FORECAST CONCERN.
MODELS ARE CONSISTENT IN KEEPING BROAD UPPER TROUGH OVER THE MIDDLE
OF THE COUNTRY THROUGH THE MIDDLE OF THE WEEK BEFORE ZONAL FLOW AND
WEAK RIDGING TAKES OVER LATE IN THE WEEK. SEVERAL IMPULSES WILL ROLL
SOUTH AND SOUTHEAST THROUGH THE TROUGH OVER THE NEXT SEVERAL
DAYS...BRINGING VARYING DEGREES OF PRECIPITATION CHANCES/TYPES TO
OUR PART OF THE COUNTRY.
A COUPLE OF SHORTWAVES THAT WILL BRING AT LEAST CLOUDS TO OUR AREA
TODAY WERE NOTED IN WATER VAPOR IMAGERY THIS MORNING. ONE WAS
DRIFTING SOUTHEAST THROUGH EASTERN SOUTH DAKOTA...AND WAS SPARKING
LIGHT PRECIPITATION THERE. THIS LOOKS TO MOVE NORTHEAST OF OUR
AREA...BUT MID LEVEL CLOUDINESS OR PERHAPS SOME LOWER CLOUDS WILL
SKIRT OUR NORTHERN CWA. ANOTHER WAVE WAS DRIFTING EAST FROM WESTERN
KANSAS...AND WAS CAUSING MID LEVEL CLOUDS IN CENTRAL NEBRASKA
ALREADY. NAM PAINTS A STRIPE OF LIGHT PRECIP IN OUR SOUTH WITH THIS
WAVE...BUT NOTHING NOTED ON AREA RADARS YET. RELATIVELY DRY LOW
LEVEL AIR SHOULD KEEP ANY OF THIS PRECIP VERY LIGHT SO NO MENTION
PLANNED.
THE NEXT WAVE WAS DIVING OUT OF THE CANADIAN ROCKIES...AND WILL MOVE
INTO SOUTH DAKOTA ON MONDAY. WARM ADVECTION AHEAD OF THIS FEATURE
WILL LIKELY PRODUCE PRECIPITATION...AND MODELS HAVE HINTED AT THIS
OVER THE LAST COUPLE OF DAYS. 06Z NAM HAS COME AROUND TO 00Z GFS AND
ECMWF SOLUTIONS IN PAINTING LIGHT PRECIP IN OUR NORTH ON MONDAY...SO
HAVE ADDED SMALL POPS TO THAT AREA. FORECAST SOUNDINGS SHOW WARM
SURFACE LAYER UP TO ABOUT 900MB...SO EXPECT LIQUID PRECIP TYPE.
A MORE SIGNIFICANT WAVE WILL ROLL INTO THE PLAINS TUESDAY AND
WEDNESDAY. BOTH ECMWF AND GFS HAVE SHOWN THIS FEATURE FOR SEVERAL
RUNS...AND ARE AGAIN CONSISTENT THIS MORNING. CURRENT RUNS SUGGEST
PRECIP MAY MOVE INTO OUR NORTHWEST AS EARLY AS TUESDAY
AFTERNOON...WITH THE BULK OF THE PRECIPITATION TUESDAY NIGHT AND
WEDNESDAY MORNING. LATITUDINAL DIFFERENCES IN REGARDS TO SURFACE LOW
PLACEMENT EXIST WITH GFS FARTHER NORTH...HOWEVER TIMING IS
CONSISTENT. EXPECT SWATH OF PRECIP FROM NORTHWEST CWA THROUGH OUR
SOUTHEAST TUESDAY NIGHT...THEN ENDING WEDNESDAY MORNING IN THE EAST.
PRECIP TYPE WILL BEGIN AS RAIN TUESDAY EVENING THEN SWITCH TO SNOW
FROM NORTHWEST TO SOUTHEAST OVERNIGHT. MOSTLY A SNOW EVENT FOR OUR
FAR NORTH MUCH OF THE NIGHT...SO HAVE INITIALLY PAINTED AN INCH OR
SO OF SNOW THERE. HOWEVER A QUICKER CHANGEOVER WOULD YIELD HIGHER
AMOUNTS...AND COULD SEE 3 INCH TOTALS COMMON FROM NORTHEAST NEBRASKA
THROUGH WEST CENTRAL IOWA BASED ON GARCIA CALCULATIONS ALONG 295K
ISENTROPIC SURFACE. WILL CONTINUE TO MENTION THIS POSSIBILITY IN
HAZARDOUS WEATHER OUTLOOK.
SNOW OR RAIN/SNOW WILL MOSTLY END BY EARLY WEDNESDAY AFTERNOON. COOL
ADVECTION ON GUSTY NORTHWEST WINDS WILL KEEP TEMPS IN THE 30S AND
LOWER 40S WEDNESDAY AFTERNOON.
A COLD START TO THURSDAY WITH TEMPS IN THE TEENS AND 20S WILL BE
FOLLOWED BY MODERATING TEMPERATURES THROUGH EARLY NEXT WEEKEND.
HIGHS SHOULD GRADUALLY WARM TOWARD 50 BY FRIDAY BEFORE WEAK FRONTAL
BOUNDARY SLIPS INTO THE PLAINS FOR SATURDAY. NO CHANGES WERE MADE TO
PREVIOUS FORECAST FOR THIS PERIOD.
DERGAN
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
06Z TAFS
SERIES OF WEAK SHORT WAVES PROGGED TO MOVE THROUGH MEAN TROUGH OVER
THE CENTRAL CONUS DURING PERIOD RESULTING IN PERIODS BKN VFR CIGS.
FOBERT
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$