000
FXUS63 KGLD 172015
AFDGLD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
215 PM MDT SAT MAY 17 2008
.DISCUSSION...
208 PM MDT SAT MAY 17 2008
17Z WATER VAPOR IMAGERY INDICATED LARGE RIDGE ACROSS THE WESTERN
CONUS WITH SHORT WAVE TROUGH MOVING ACROSS TEXAS. AT THE
SFC...BREEZY NORTHWESTERLY WINDS WERE COMMON ACROSS THE ENTIRE CWA.
WITH RIDGING IN CONTROL OF AREA THROUGH THE SHORT TERM...TEMPS WILL
BE PRIMARY CONCERN.
TONIGHT...H5 RIDGE WILL CONTINUE BUILD OVER THE AREA THROUGH THE
PERIOD. DESPITE NVA ASSOCIATED WITH RIDGE...DIV Q FIELDS INDICATE
WAA MAY BE STRONG ENOUGH FOR WEAK ASCENT TONIGHT...BUT PROFILES VERY
DRY AND STABLE AND WOULD EXPECT LITTLE MORE THAN A FEW MID LEVEL
CLOUDS OVERNIGHT.
SUNDAY-SUNDAY NIGHT..H5 RIDGE WILL CONTINUE TO IMPACT THE REGION
WITH LITTLE IF ANY FORCING OCCURRING ACROSS THE AREA. LEE TROUGH
DEVELOPS DURING THE DAY WITH SOME CONVERGENCE ALONG IT...BUT ANY
MEANINGFUL MOISTURE RETURN LOOKS UNLIKELY AHEAD OF THE
TROUGH...KEEPING THINGS DRY. FIRE WX CONCERNS WILL ALSO ONCE AGAIN
DEVELOP DURING THE AFTERNOON BEHIND THE SFC TROUGH. ALTHOUGH AMOUNT
OF DRYING IS A BIT UNCERTAIN DUE TO THE SPREAD IN OBSERVED TDS
UPSTREAM...MIXED LAYER TD`S AND FORECAST TEMPERATURES SUPPORT RHS
FALLING INTO THE 10 TO 15 PERCENT RANGE TOMORROW AFTERNOON. ALREADY
HITTING RH CRITERIA TODAY AND WITH WARMER TEMPS TOMORROW CRITICAL RH
VALUES SEEM LIKELY. MAIN QUESTION IS THE WIND...AS LIGHT WINDS WILL
BE COMMON ACROSS THE AREA AHEAD OF THE TROUGH. BEHIND THE
TROUGH...WINDS WILL BEGIN TO PICK UP INTO THE 10 TO 20KT RANGE...BUT
GETTING THE PERSISTENT GUSTS TO 25 MPH FOR SEVERAL HOURS APPEARS
QUESTIONABLE AT THIS POINT. MAY SEE A GUST OR TWO HIT 25 MPH...BUT
CONFIDENCE IS LOW. WITH WARNING ALREADY IN PLACE AND MARGINAL SET UP
FOR A WATCH TOMORROW...WILL HOLD OFF ANY HIGHLIGHTS FOR NOW.
MONDAY-TUESDAY...CWA REMAINS ON PERIPHERY OF LARGE H5 RIDGE THROUGH
THE PERIOD. SHORT WAVE TROUGH WILL SLIDE AROUND RIDGE ACROSS
MINNESOTA...HELPING DRIVE A WEAK COLD FRONT ACROSS THE AREA. SOME
VERY WEAK INSTABILITY DEVELOPS AHEAD OF THIS FRONT...BUT WITH
SYNOPTIC SCALE NOT REALLY FAVORABLE DO NOT THINK ANYTHING WILL FORM.
AREA OF ISENTROPIC ASCENT/WAA DEVELOPS ACROSS THE CWA OVER TOP THE
SHALLOW FRONTAL ZONE. NAM SUGGESTS SOME INSTABILITY DEVELOPING ABOVE
FRONTAL ZONE IN AREA OF ASCENT...BUT GFS MUCH MORE STABLE. ALSO MAY
BE SOME POTENTIAL FOR SFC BASED CONVECTION LATE IN THE DAY AS NARROW
INSTABILITY AXIS DEVELOPS ACROSS EASTERN COLORADO. SOUTHEAST
FLOW/WEAK OROGRAPHIC FORCING COULD BE ENOUGH TO SET OFF A STORM OR
TWO...BUT FAIRLY STRONG CAP IN PLACE. FOR NOW...PLAN ON KEEPING
FORECAST DRY BUT WILL HAVE TO KEEP AN EYE ON THIS PERIOD.
IN THE EXTENDED...MAIN CONCERN FOR THE PERIOD WILL BE DEVELOPMENT OF
LARGE H5 TROUGH ACROSS THE WESTERN CONUS AND ASSOCIATED IMPACTS
ACROSS THE CWA. WHILE MODELS HAVE HAD VARIOUS SOLUTIONS TO THE
HANDLING THIS TROUGH...ECMWF HAS GENERALLY HAD THE MOST CONSISTENCY
ALTHOUGH DETAILS VARY. 06Z GFS LOOKS A LOT LIKE 00Z ECMWF AND 00Z
GFS ENSEMBLE MEAN...WITH BOTH 00Z AND 06Z 570 DM SPAGHETTI DIAGRAMS
FAVORING A SOLUTION SIMILAR TO 06Z GFS/00Z ECMWF AND PLAN TO LEAN
THIS WAY FOR FORECAST.
ALTHOUGH GFS AND ECMWF LOOK A LOT ALIKE ALOFT...SMALL CHANGES WITH
THE ORIENTATION OF TROUGH AND DEVELOPMENT OF CLOSED LOW OFF OF THE
SW COAST. ECMWF MORE AMPLIFIED SOLUTION KEEPS DEEP SOUTHERLY FLOW
ACROSS THE ARE THROUGH THE PERIOD WHICH WOULD SEEM TO INHIBIT ANY
FRONTAL PASSAGES. GFS HAS SLIGHTLY MORE SOUTHWESTERLY FLOW AND MORE
TILT WITH THE TROUGH...AND EVENTUALLY SPLITS TROUGH INTO SOUTHERN
CUT OFF AND NORTHERN STREAM TROUGH. 00 AND 06Z GFS ENSEMBLE MEMBERS
AND CMC MEAN REALLY SUPPORT THIS IDEA LATE IN THE PERIOD.
DIFFERENCES MAKE DETERMINING THE MOST LIKELY SFC FLOW
DIFFICULT...ALTHOUGH H25 ISOTACHS /PV FIELDS/DIV Q WOULD SUGGEST
THAT SYNOPTIC SCALE FORCING WOULD GENERALLY KEEP ANY SFC LOWS ACROSS
WYOMING/NEB PANHANDLE THROUGH FRIDAY WHICH SHOULD KEEP FLOW
GENERALLY SOUTH SOUTH EASTERLY. AFTER THAT...IF TROUGH DOES SPLIT
WOULD SEEM LIKELY TO GET A FRONTAL PASSAGE BUT CONFIDENCE FAIRLY LOW
AT THIS POINT.
SEVERAL POTENTIAL CONCERNS THROUGH THE PERIOD...FIRST BEING
POTENTIAL FOR SEVERAL ROUNDS OF THUNDERSTORMS/SEVERE WX THROUGH THE
END OF THE WEEK. MODELS HAVE BEEN TRENDING FURTHER WEST WITH DRY
LINE POSITION THE LAST FEW RUNS...WITH ECMWF PUSHING IT ALL THE WAY
BACK TO LIC BY FRIDAY. DIFFERENCES REALLY SEEM TO CENTER AROUND
WHETHER TROUGH WILL SPLIT OR NOT. WITH POSITION OF THE
TROUGH...WOULD EXPECT PRESSURE FALLS SOMEWHERE TO THE WEST NORTHWEST
OF THE CWA...WHICH WILL HELP ADD AN EASTERLY COMPONENT TO WINDS AND
WOULD EXPECT THAT TO HELP HOLD DRYLINE BACK...SO GENERALLY WENT THAT
WAY WITH THE FORECAST. WITH THE POSITION OF THE TROUGH AND FAIRLY
STRONG WINDS ALOFT...LOOKS LIKE SEVERAL ROUNDS OF STRONG/SEVERE
WEATHER POSSIBLE THROUGH SATURDAY. OTHER CONCERN WILL BE FIRE
WX...WHICH ALSO DEPENDS ON DRYLINE POSITION. ECMWF/GFS SUGGEST VERY
DRY AIR ON WEST OF DRY LINE AND WITH WINDY CONDITIONS DEVELOPING
THURS AND FRI AFTERNOON...ANY LOCATION THAT DOESNT HAVE SVR
POTENTIAL WILL LIKELY MEET RED FLAG WARNING CONDITIONS. TO FAR OUT TO
NEED HIGHLIGHTS ATTM...BUT WILL NEED TO BE WATCHED.
JRM
&&
.AVIATION...
1144 AM MDT SAT MAY 17 2008
FOR THE 18Z TAF CYCLE...VFR CONDITIONS WILL PREVAIL THROUGHOUT THE
ENTIRE TAF PERIOD. ONLY FEW/SCT MID- TO UPPER-LEVEL CLOUDS ARE
EXPECTED FOR BOTH KGLD AND KMCK. BREEZY WINDS FROM THE NORTH AT 20
TO 30 MPH ARE EXPECTED TO DIMINISH AFTER 00Z AND BECOME LIGHT FROM
THE WEST BY 06Z.
BLM
&&
.FIRE WEATHER...
208 PM MDT SAT MAY 17 2008
RED FLAG WARNING WILL CONTINUE ACROSS ENTIRE AREA UNTIL 00Z...WHEN
WINDS BEGIN TO DECOUPLE AND HUMIDITIES RECOVER. RELATIVE
HUMIDITIES WILL ONCE AGAIN DROP TO THE 10 TO 15 PERCENT RANGE
TOMORROW...BUT WINDS ARE EXPECTED TO BE MUCH KIGHTER AND GENERALLY
IN THE 10 TO 20 MPH RANGE. POTENTIALLY CRTICAL FIRE WEATHER
CONDTIONS WILL BE POSSIBLE ACROSS THE AREA AGAIN ON WEDNESDAY AND
THURSDAY AS A DRYLINE DEVELOPS ACROSS THE AREA. ANYONE WITH
BURNING PLANS FOR THE MIDDLE OF THE WEEK SHOULD KEEP MONITORING
THE LATEST FORECASTS.
JRM
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...RED FLAG WARNING UNTIL 6 PM MDT /7 PM CDT/ THIS AFTERNOON FOR
KSZ001>004-013>016-027>029-041-042.
NE...RED FLAG WARNING UNTIL 6 PM MDT /7 PM CDT/ THIS AFTERNOON FOR
NEZ079>081.
CO...RED FLAG WARNING UNTIL 6 PM MDT THIS AFTERNOON FOR COZ252>254.
&&
$$
WFO GOODLAND
