FXUS63 KOAX 211927
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
227 PM CDT THU OCT 21 2010
.SHORT TERM...TONIGHT THROUGH SUNDAY.
RAIN CHANCES THROUGH THE WEEKEND AND AFFECTS ON TEMPERATURES ARE THE
MAIN FORECAST CHALLENGES.
UPPER LOW MOVING IN FROM THE SOUTHWEST WAS BEGINNING TO INFLUENCE
WEATHER PATTERN IN THE PLAINS THIS AFTERNOON AS NORTHEAST WINDS WERE
BEGINNING TO VEER TO SOUTHEAST IN OUR WESTERN CWA. HIGH CLOUDS WERE
STILL WELL TO THE SOUTHWEST...ALLOWING TEMPERATURES TO REBOUND INTO
THE 60S. MORNING UPPER AIR CHARTS SHOWED 850 MOISTURE BEGINNING TO
SURGE NORTH IN THE HIGH PLAINS WITH 10C+ DEW POINTS NOTED IN WESTERN
KANSAS.
LOW AND MID LEVEL MOISTURE ARE FORECAST TO SPREAD NORTHEAST WITH
TIME TONIGHT AND THROUGH THE WEEKEND. MODELS HAVE BEEN HINTING
OVER THE LAST FEW DAYS AT THICKENING MID LEVEL CLOUDS IN OUR CWA
TONIGHT...BUT THIS MORNING NAM/GFS WERE SQUEEZING OUT QPF IN
SOUTHEAST NEBRASKA. STRENGTH OF WARM/MOIST ADVECTION WILL LIKELY
PRODUCE SOME ACCAS THERE...BUT LOW LEVEL DRY AIR SHOULD EVAPORATE
RAIN BEFORE HITTING THE GROUND. HOWEVER WILL LIKELY INSERT A SMALL
CHANCE FOR SHOWERS/THUNDER IN OUR SOUTH LATER TONIGHT.
BETTER CHANCES FOR RAIN/THUNDER COME LATER FRIDAY AFTERNOON/NIGHT.
DIFFLUENT FLOW ALOFT COMBINED WITH MOISTENING LOW LEVELS WILL LEAD
TO SHOWERS IN OUR SOUTH BY FRIDAY AFTERNOON...THEN SPREADING ACROSS
ALL OF THE CWA FRIDAY NIGHT. HAVE CONTINUED LIKELY POPS FOR THIS
TIME.
SATURDAY IS A BIT MORE IN QUESTION WITH UPPER LOW MOVING INTO OUR
AREA AND AFFECTS OF DRY SLOT ON SOUTH SIDE OF LOW. EXPECT COMMA HEAD
SHOWERS CONTINUING IN OUR NORTH MUCH OF THE DAY...AND A LIKELY BREAK
IN PRECIPITATION IN THE SOUTH WHERE MID LEVEL MOISTURE IS SCOURED
OUT. HOWEVER...SURGING TEMPERATURES IN DRY SLOT ALONG WITH DEW
POINTS APPROACHING 60 WILL LEAD TO MODEST INSTABILITY FOR THIS
TIME OF YEAR. DAY 3 CONVECTIVE OUTLOOK PAINTS A SLIGHT RISK FOR
SEVERE FROM SOUTHEAST NEBRASKA AND SOUTHWEST IOWA SOUTH...BUT ALSO
CAUTIONS ON TIMING/PLACEMENT OF SURFACE FEATURES AND INSTABILITY.
IF ANY STORMS DO FIRE IN OUR SOUTHEAST CWA...THEY SHOULD HAVE
PLENTY OF INSTABILITY AND SHEAR TO YIELD A CHANCE FOR
STRONG/SEVERE STORMS. WILL LET LATER SHIFTS ANALYZE THIS
FURTHER...AND FOR NOW INSERT THUNDERSTORMS TO GRIDS AND MENTION
POTENTIAL SEVERE IN HAZARDOUS WEATHER OUTLOOK.
LINGERING STORMS ARE POSSIBLE SATURDAY EVENING...WITH MORE
SHOWERY/RAIN TAKING OVER SATURDAY NIGHT AND SUNDAY UNDER CORE OF
UPPER LOW. GFS MOVES SYSTEM OUT MUCH MORE QUICKLY THAN NAM...AND
WOULD SUGGEST MOST OF SUNDAY WOULD BE DRY. GIVEN THESE SYSTEMS ARE
NORMALLY SLOWER THAN MODEL PROGS...AND THIS PARTICULAR SYSTEM HAS
BEEN SLOWED DOWN BY MODELS ALL WEEK...WILL CONTINUE WITH AT LEAST
SMALL RAIN CHANCES ALL DAY SUNDAY.
TEMPERATURES FRIDAY ARE LOOKING WARMER THAN FIRST THOUGHT EARLIER IN
THE WEEK. SOUTHERLY FLOW AND INCREASING LOW LEVEL MOISTURE SHOULD
PUSH HIGHS IN TO THE 70S. COOLER SPOTS IN THE SOUTH ARE POSSIBLE
WHERE CLOUDS WILL BE THICKER AND PRECIP CHANCES HIGHER. SATURDAY
COULD YIELD A TIGHT GRADIENT IN TEMPS WITH LOWER 60S IN THE NORTH
UNDER CLOUDS/RAIN...AND MID 70S IN THE SOUTH IN DRY SLOT. COOLER
TEMPS IN THE 60S OR EVEN 50S LOOK PROBABLE ON SUNDAY UNDER CLOUD
COVER AND UPPER LOW/TROUGH.
DERGAN
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY.
EXTENDED PERIODS REMAIN QUITE COMPLEX AS TWO SYSTEMS MOVE ACROSS THE
REGION. UPPER LOW SHOULD BE WELL EAST OF THE AREA BY SUNDAY NIGHT.
STRONG WAA WILL BE UNDERWAY OVERNIGHT SUNDAY AND INTO MONDAY. CLOUD
COVER WL BE LIMITING FACTOR FOR HIGHS WARMING INTO THE MID TO UPPER
60S...WITH NEAR 70S POSSIBLE IN THE SOUTH. AN UPPER LOW IS FORECAST
TO MOVE EWD ACROSS THE DAKOTAS WHICH WL DRIVE A COLD FRONT INTO THE
AREA BY LATE MONDAY. WL CONTINUE CHANCE POPS ALONG THE BOUNDARY LATE
MONDAY AND INTO MONDAY NIGHT. THE UPPER LOW SHOULD PROGRESS INTO
ONTARIO BY TUESDAY NIGHT. THIS LEAVES THE FORECAST AREA DRY BEFORE A
SOUTHWESTERN US TROF DIGS INTO THE HIGH PLAINS REGION. THERE
CONTINUE TO BE MODEL DISCREPANCIES AND TIMING ISSUES ASSOCIATED WITH
THIS STRONG TROF...BUT HAVE FOLLOWED WITH HPC'S GUIDANCE AND
CONTINUED THE FORECAST MORE CLOSELY TO THE ECMWF. THIS WOULD ALLOW
COLD AIR TO DIVE SOUTH INTO THE SYSTEM ON THURSDAY AS IT CONTINUES
TO PROGRESS ACROSS THE CNTRL PLAINS. HAVE MENTIONED A RA/SN MIX IN
THE FAR NORTHERN COUNTIES...HOWEVER UNCERTAINTY REMAINS REGARDING
THE EVOLUTION OF THIS SYSTEM.
KERN
&&
.AVIATION...
TAF SITES KOFK/KOMA/KLNK
18Z TAFS
VFR CONDITIONS WILL CONTINUE THROUGH FORECAST PD. A LARGE UPPER
LEVEL LOW PRESSURE SYSTEM WILL BEGIN TO IMPACT AREA BEYOND TAF
FORECAST VALID TIMEFRAME...LATE FRI INTO SAT...BUT SOME HIGHER
CLOUDS EXPECTED TO BEGIN TO MOVE INTO AREA IN ADVANCE OF THIS
SYSTEM AFTER 22/06Z.
FOBERT
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&
$$
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