000
FXUS63 KFGF 171918
AFDFGF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
218 PM CDT SAT MAY 17 2008
.SHORT TERM...
QUITE A FEW FORECAST CHALLENGES IN THE NEAR TERM...INCLUDING WIND
...CRITICAL FIRE WEATHER CONDITIONS AND FROST POTENTIAL TONIGHT.
MODELS DID A GOOD JOB FORECASTING THE WIND SPEEDS TODAY AND THERE
IS GOOD CONTINUITY ON THE QUICK DROP OFF AGAIN TONIGHT. FROST
POTENTIAL IS A DIFFERENT STORY...AS MODELS HAVE HAD A HARD TIME
NAILING THE DRY BOUNDARY LAYER (WHICH IS MORE LIKE A LATE MARCH
OR APRIL AIRMASS...NOT A MID MAY ONE). WILL USE A MODEL BLEND FOR
THIS FORECAST.
TONIGHT...WIND SPEEDS CAME UP A BIT FASTER TODAY THAN THEY DID ON
FRIDAY. HOWEVER...THE OVERALL SETUP WAS HANDLED VERY WELL. MODEL
SOUNDINGS SHOWED MIXING POTENTIAL TO AT LEAST 700MB...WITH ABOUT
40KTS AVAILABLE TO MIX DOWN. NUMEROUS 40-45KT GUSTS ACROSS THE
AREA...WITH QUITE A FEW OF THEM IN THE VICINITY OF SHOWERS...WHICH
WERE MOSTLY LOCATED ON THE EXTREME EASTERN FRINGE OF THE FA
(OUTSIDE THE ACTUAL WIND ADVISORY AREA). HOWEVER...THESE GUSTS ON
THE EASTERN FRINGE WERE NOT LONG IN DURATION AND THE SUSTAINED
WINDS DID NOT REMAIN HIGH FOR VERY LONG. AS THE SHOWERS ALSO
APPEAR TO BE MOVING AT ABOUT 40-45KTS...THEY ARE NOT LOCATED IN
ONE SPOT VERY LONG. HAVE HAD A COUPLE OF LIGHTNING STRIKES IN THIS
AREA TOO...BUT THIS IS PRETTY RARE AND WILL NOT MENTION THUNDER
INTO THE EVENING...BUT KEEP PCPN TYPE AS SHOWERS. WILL JUST KEEP
THESE SHOWERS ALONG THE EASTERN FRINGE THRU ABOUT 03Z TONIGHT. RED
FLAG WARNING WAS ALSO A GOOD CALL...WITH 2 PM OBSERVATIONS SHOWING
HUMIDITY LEVELS DOWN INTO THE TEENS. SFC DEW POINTS HAVE NOT BEEN
HANDLED WELL BY THE MODELS...AND AT 2 PM THE OBSERVATIONS ALSO
SHOWED A GOOD SWATH OF LOW TO MID 20 DEW POINTS IN THE FA. THIS
WILL ALSO AFFECT THE MIN TEMP FORECAST TONIGHT. WITH WIND SPEEDS
DYING OFF BY MID TO LATE EVENING AND CELLULAR CUMULUS
DISSIPATING...TEMPS WILL DROP QUICKLY. WILL UNDERCUT MODEL
GUIDANCE BASICALLY ACROSS THE BOARD. THIS GIVES TEMPS IN THE LOW
30S ACROSS MOSTLY THE NORTHERN HALF OF THE FA. SINCE WE HAVE
PASSED INTO THE GROWING SEASON NOW AND SOME PEOPLE HAVE ALREADY
PLANTED SENSITIVE PLANTS...WILL ISSUE A FROST ADVISORY FOR THE
NORTHERN HALF OF THE FA. THIS MAY NEED TO BE EXPANDED...BUT THE
EVENING SHIFT CAN MONITOR THAT.
SUNDAY-TUE NIGHT...SFC HIGH SHOULD BE RIGHT OVERHEAD ON SUNDAY
MORNING. THEREFORE SHOULD FINALLY NOT HAVE TO WORRY ABOUT FIRE
WEATHER OR WIND HEADLINES. AFTER THE COOL START...TEMPS ARE
EXPECTED TO STRUGGLE TO REACH THE LOW-MID 60S. MODELS ARE FAIRLY
CONSISTENT IN KEEPING SOME LOW CHANCES FOR PCPN SUNDAY NIGHT...AND
THEN MAINLY WEST OF THE RED RIVER. INSTABILITY PARAMETERS LOOK
BETTER WEST OF THE FA...SO WILL KEEP PCPN TYPE AS SHOWERS. CLIPPER
TYPE SYSTEM APPROACHES THE FA MONDAY AND MONDAY NIGHT. KEPT BEST
CHANCES FOR PCPN WITH THIS SYSTEM IN THE NORTH.
.LONG TERM [WED-SAT]...
MAIN CHALLENGE WILL BE DEVELOPING SW FLOW ALOFT DUE TO DEEPENING
W CONUS TROUGH. PERIODIC SHORTWAVES WITHIN THIS FLOW WOULD GIVE
NUMEROUS CHANCES FOR SHOWERS THROUGH THE PERIOD. 12Z MODELS
(GFS/GFS ENSEMBLE/CANADIAN/ECMWF) SHOWING SLOWER DEVELOPMENT TO
OVERALL PATTERN. THIS WOULD KEEP THE FA UNDER THE INFLUENCE OF THE
UPPER RIDGE DELAYING ONSET OF PRECIP (POSSIBLY UNTIL FRI). WOULD
LIKE TO SEE THIS TREND CONTINUE ANOTHER SET OF MODEL RUNS BEFORE
MAKING DRASTIC CHANGES. FOR NOW...WILL TREND POPS DOWN ONLY
SLIGHTLY WED-THUR. TEMPERATURES WILL DEPEND ON PRECIP CHANCES...
BUT GENERALLY NEAR NORMAL.
&&
.AVIATION...
STRONG WINDS WILL QUICKLY DIE OFF THIS EVENING. AFTERNOON CU WILL
QUICKLY DISSIPATE. THIS WILL LEAVE MOSTLY CLEAR SKIES WITH LIGHT
WINDS THROUGH THE NIGHT INTO THE MORNING HOURS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...RED FLAG WARNING UNTIL 9 PM CDT THIS EVENING FOR NDZ006>008-
014>016-024-026>030-038-039-049-052>054.
WIND ADVISORY UNTIL 9 PM CDT THIS EVENING FOR NDZ006>008-014>016-
024-026>030-038-039-049-052>054.
FROST ADVISORY FROM 1 AM TO 9 AM CDT SUNDAY FOR NDZ006>008-
014>016-024-026>030-038-054.
MN...WIND ADVISORY UNTIL 9 PM CDT THIS EVENING FOR MNZ001>005-007-008-
013>015-022-027-029-030-040.
FROST ADVISORY FROM 1 AM TO 9 AM CDT SUNDAY FOR MNZ001-002-
004>009-013>017-022>024.
&&
$$
GODON/TG
