235
FXUS63 KFGF 210153
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
753 PM CST FRI NOV 20 2009
DISCUSSION
THE MAIN CHALLENGE OVERNIGHT WILL BE TEMPS. THE PRESSURE GRADIENT
WILL SLOWLY TIGHTEN OVERNIGHT...ALONG WITH INCREASING HIGH CLOUDS.
WARM AIR ADVECTION ABOVE THE SFC WILL ALSO INCREASE. THIS SHOULD
ALL SERVE TO HOLD TEMPS UP OVERNIGHT SO WILL INCREASE OVERNIGHT
LOWS A BIT MAINLY ALONG AND WEST OF THE VALLEY WHERE WINDS WILL BE
A BIT STRONGER THAN FURTHER EAST.
ON SATURDAY...WINDS SHOULD INCREASE WITH A TIGHT PRESSURE GRADIENT
AND NEARLY 45KT TO MIX FROM 925MB BY AFTERNOON. THE MAIN QUESTION
WILL BE WHAT LEVEL MIX DOWN FROM. IF WINDS CAN MIX FROM
925MB...THEN A WIND ADVISORY MAY BE NEEDED FOR TOMORROW. IT WILL
BE WINDY NONETHELESS...SO HAVE INCREASE WINDS IN THE GRIDS TO
REFLECT THIS REASONING.
AVIATION
SOUTHERLY WINDS WILL INCREASE BY SATURDAY AFTERNOON WITH GUSTS
FROM 30-35KT POSSIBLE AT ALL SITES. VFR CONDITIONS WILL BE
EXPECTED OTHERWISE WITH JUST SOME VERY HIGH CIRRUS AT TIMES
THROUGH SATURDAY.
PREV DISCUSSION
/ISSUED 259 PM CST FRI NOV 20 2009/
SHORT TERM...
MAIN FCST CHALLENGE WILL BE TEMPS AND WINDS FOR SATURDAY. MODELS
INITIALIZED WELL BUT GFS DIVERGES FROM REST OF ENSEMBLE SO WILL GO
WITH A BLENDED NAM/ECMWF/GEMS SOLN ATTM.
SFC ANALYSIS SHOWS RIDGE AXIS OVER CENTRAL PORTION OF MN SHIFTING E
ALLOWING SRLY WINDS TO DEVELOP ACROSS THE AREA. ABUNDANT SUNSHINE
WILL KEEP TEMPS PROPPED UP THIS AFTERNOON AND INCREASING
THICKNESSES...ALONG WITH INCREASING CLOUD COVER...WILL LIMIT COOLING
OVERNIGHT.
PACIFIC FRONT WILL BEGIN PUSHING INTO THE DVL BASIN LATE SAT
AFTERNOON AND EXIT THE AREA BY LATE SAT NIGHT. AHEAD OF THE
FRONT...PRESSURE GRADIENT INCREASES AND 850MB WINDS OF 40 TO 50
KNOTS IS EXPECTED TO MIX DOWN TO THE SFC. THEREFORE...LOOKING TO SEE
SFC GUSTS APPROACHING 30 MPH FROM THE VALLEY WEST...BUT NOT
ANTICIPATING REACHING ADVISORY CRITERIA ATTM. COOLER AIR BEHIND THE
FRONT WILL DROP TEMPS TO MORE SEASONAL VALUES. WITH LIMITED
MOISTURE DUE TO DRIER AIR IN THE LOWER LEVELS...NOT ANTICIPATING
MUCH IN THE WAY OF PCPN WITH THE FRONT.
FOR MONDAY...DEVELOPING LOW PRESSURE SYSTEM IN THE CENTRAL PLAINS
WILL PROVIDE THE NEXT CHANCE FOR PCPN AS INVERTED TROF CROSSES THE
REGION. ANTICIPATE MOST OF THE MOISTURE WILL REMAIN SOUTH AS IT
WRAPS INTO THE LOW...BUT SUFFICIENT MOISTURE SHOULD PUSH N AND LIFT
ASSOCIATED WITH THE TROF WILL HELP PRODUCE -RA...MAINLY E OF THE
VALLEY.
LONG TERM (TUE-FRI)...
THE LONG RANGE MODELS QUICKLY DIVERGE ON TIMING OF 500MB TROF/LOW AS
IT MOVES THROUGH THE PLAINS AND INTO THE GREAT LAKES REGION FOR THE
MIDDLE PART OF NEXT WEEK. THE GFS IS THE MEAN SOLUTION BETWEEN THE
DGEX AND ECMWF AT THIS TIME. HOWEVER...THE ECMWF IS PREFERRED AT
THIS TIME BECAUSE IT HAS BEEN THE MOST CONSISTENT. THUS...STILL KEPT
CHC POPS FOR PCPN IN FORECAST FOR TUE AND TRENDED INTO E PARTS OF
AREA FOR WED. AS FAR AS TEMPS...LOOK FOR TEMPERATURES TO REMAIN
SLIGHTLY ABOVE NORMAL THROUGH THE EXTENDED FORECAST.
FGF WATCHES/WARNINGS/ADVISORIES
ND...NONE.
MN...NONE.
DK
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