877
FXUS63 KOAX 161952
AFDOAX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
252 PM CDT FRI MAY 16 2008
DISCUSSION
PRIMARY FORECAST CONCERN FOR TONIGHT IS THE CHANCE FOR PCPN. ATTENTION
SHIFTS TO MAINLY TEMPERATURES FOR SATURDAY THROUGH TUESDAY...BUT THERE
IS AT LEAST A SLIGHT CHANCE FOR SHOWERS MONDAY NIGHT. PATTERN SHOULD
TURN ACTIVE FOR THE MID AND LATTER PART OF NEXT WEEK.
THE UPPER AIR CHARTS FROM 12Z AND LATEST SATELLITE WATER VAPOR IMAGES
INDICATED A VERY STRONG MID TROPOSPHERIC RIDGE ALONG THE WEST COAST
OF THE U.S. THAT EXTENDED UP INTO BRITISH COLUMBIA. A CLOSED LOW WAS
JUST EAST OF THE CHIHUAHUA/SONORA BORDER...AND A TROUGH STRETCHED
FROM HUDSON BAY DOWN INTO THE GREAT LAKES REGION. CLOSER TO HOME...
THERE WAS A SHORTWAVE DROPPING SOUTHEASTWARD FROM EASTERN MONTANA
AND WESTERN NORTH DAKOTA.
FOR TONIGHT...WILL KEEP MENTION OF ISOLATED SHOWERS ACROSS ABOUT THE
NORTHERN HALF OF THE AREA UNTIL MIDNIGHT. 12Z GFS OUTPUT GENERALLY
SUPPORTS THIS IDEA...AND FAVOR IT OVER THE 12Z NAM IN REGARDS TO THE
CHANCE OF RAIN AND CLOUDS. 12Z NAM WILL PROBABLY HANDLE THE SURFACE
PATTERN AND LOW LEVEL WINDS BETTER THOUGH. WENT WITH LOWS 50 TO 55.
WEAK LOW LEVEL COLD AIR ADVECTION IS EXPECTED FOR LATER TONIGHT AND
SATURDAY MORNING...BUT 850 MB TEMPERATURES WILL REBOUND A LITTLE BY
SATURDAY EVENING. WENT CLOSE TO PREVIOUS FORECAST...WITH HIGHS 75 TO
80 NORTH AND AROUND 80 SOUTH.
MID TROPOSPHERIC RIDGE TO OUR WEST WILL GRADUALLY FLATTEN DURING THE
WEEKEND AND THEN BUILD EASTWARD EARLY NEXT WEEK. ALTHOUGH THE PATTERN
SUGGESTS MAINLY DRY WEATHER...THERE IS A DECENT SETUP FOR SHOWERS
SUNDAY NIGHT WITH SOUTHERLY LOW LEVEL FLOW AND NORTHWEST FLOW ALOFT.
BOTH THE 00Z ECMWF AND LATEST GFS SUGGEST POTENTIAL FOR PCPN WITH
INCREASING 850 TO 700 MB MOISTURE AND ISENTROPIC UPGLIDE.
HIGHS FROM SUNDAY THROUGH WEDNESDAY WILL PROBABLY BE IN THE MID 70S
TO MID 80S WITH LOWS IN THE 50S TO AROUND 60.
MID LEVEL FLOW TURNS TO THE WEST AND THEN SOUTHWEST DURING THE DAY
WEDNESDAY. THE MODELS ARE IN GENERAL AGREEMENT THAT A TROUGH WILL
DEVELOP TO WEST AND PATTERN WILL TURN ACTIVE WITH DECENT MOISTURE
AVAILABLE FROM THE GULF OF MEXICO. TIMING THE BEST CHANCES FOR PCPN
WILL NOT BE EASY. MOSTLY BECAUSE ALTHOUGH THERE IS GENERAL AGREEMENT
ON THE PATTERN ALOFT...THERE IS A FAIR AMOUNT OF DISAGREEMENT WITH
THE SURFACE PATTERN. ECMWF KEPT A SURFACE LOW OVER THE WESTERN
HIGH PLAINS...WITH OUR AREA IN SOUTH OR SOUTHEAST LOW LEVEL FLOW.
THE 12Z GFS BROUGHT A FRONT EASTWARD AND TURNED WINDS TO THE NORTH.
FOR NOW...STAYED FAIRLY CLOSE TO GUIDANCE FROM HPC WHICH FAVORED THE
ECMWF SOLUTION. CONFIDENCE ON THIS IS ABOUT NORMAL...FOR DAY 7.
BUT I WOULD HAVE GONE MORE WITH THE 12Z GFS SOLUTION...OR A BLEND
OF THE GFS AND ECMWF.
AVIATION
FOR TAF SITES KOMA...KLNK AND KOFK.
NO SIGNIFICANT AVIATION CONCERNS WITH VFR CONDITIONS PREVAILING
THROUGH 17/18Z.
OAX WATCHES/WARNINGS/ADVISORIES
NE...NONE.
IA...NONE.
DISCUSSION...BCM
AVIATION...DEE
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