905
FXUS63 KFSD 161128
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
628 AM CDT WED OCT 16 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 312 AM CDT WED OCT 16 2013
STRONG DRYING AT ALL LEVELS WILL END LINGERING LIGHT SHOWERS AND
DRIZZLE BEFORE DAYBREAK...AND CONTINUE TO CLEAR CLOUDS FROM THE
NORTHWEST. AT DAYBREAK MIDDLE CLOUDS WILL BE GONE AND LOW CLOUDS
WILL LINGER OVER MAYBE HALF OF NORTHWEST IOWA...TO CLEAR OUR OF
THERE WITHIN ABOUT 3 HOURS. THE SUBSIDENCE AND DRYING SHOULD BE MORE
THAN STRONG ENOUGH TO PREVENT CUMULUS FORMATION WITH HEATING SO WE
ARE LOOKING AT SUNNY SKIES AFTER THE ABOVE MENTIONED CLEARING.
TEMPERATURES WILL REACH THE 50S FOR HIGHS...AS WE HAVE BEEN GOING
FOR...AND PROBABLY MID TO UPPER 50S AT THAT. A TOLERABLE WESTERLY
BREEZE SHOULD PEAK AT 10 TO 15 MPH. TONIGHT WILL BRING GENERALLY A
20 DEGREE DROP FROM HIGHS FOR MINIMUM TEMPERATURES. SKIES SHOULD BE
PARTLY CLOUDY OVERALL TONIGHT. BOTH NAM AND GFS SHOW A PRONOUNCED
INCREASE IN MOISTURE ABOUT 15K FEET PLUS...SUGGESTING SOME KIND OF A
DENSE OR SEMI DENSE CLOUD DECK...SO IT COULD GO MOSTLY CLOUDY OR BE
THIN ENOUGH FOR MOSTLY CLEAR. ALL THIS WILL BE AHEAD OF THE MAIN LOW
AND MID CLOUDS WITH APPROACHING COLD FRONT...THROUGH 17/12Z ANYWAY.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 312 AM CDT WED OCT 16 2013
ON THURSDAY...FAIRLY VIGOROUS MID AND UPPER LEVEL LOW DIVES DOWN
FROM THE NORTHWEST ACROSS THE NORTHERN AND CENTRAL PLAINS. THIS
WAVE IS CLEARLY MARKED BY BOTH THE NAM AND GFS UPPER QG FORCING.
IN ADDITION...BOTH MODELS SHOW SOME DECENT MOISTURE DEPTH THROUGH
AT LEAST 700MB ALONG AND NORTH OF I 90. THE FRONTAL BOUNDARY THAT
IS ASSOCIATED WITH THIS WAVE IS NOT REAL STRONG. BUT IT IS STRONG
ENOUGH TO KICK UP THE WINDS BEHIND THE WIND SHIFT AND BRINGS IN
SOME MODEST COLD AIR ADVECTION WHICH WILL LIKELY PUT THE BRAKES ON
DAYTIME TEMPERATURES AFTER THE FRONTAL PASSAGE. SLIGHT CHANCE TO
CHANCE POPS ARE CERTAINLY WARRANTED FOR NOW OVER MUCH OF OUR
FORECAST AREA...MINUS THE SIOUX CITY TO STORM LAKE REGION WHERE
THE DEPTH OF MOISTURE IS LACKING SOME. WHEN THE TIME COMES...THIS
COULD TURN INTO A HIGH POP...LOW QPF EVENT FOR AREAS NORTH OF
INTERSTATE 90. HIGHS ON THURSDAY WILL RANGE FROM ABOUT 50
NORTH...TO 60 SOUTH. AND AGAIN...BREEZY CONDITIONS MENTIONED ABOVE
WILL GIVE THE AIR AN EXTRA CHILL.
AFTER THURSDAYS WAVE PASSAGE...SKIES SHOULD CLEAR THURSDAY NIGHT
BEFORE CLOUDING RIGHT BACK UP AGAIN WITH THE NEXT UPPER
DISTURBANCE MOVING THROUGH ON FRIDAY. THIS WAVE IS WEAKER THEN
THURSDAYS...AND MOISTURE DEPTH IS GENERALLY NOT AS DEEP. BUT IT IS
SHOWING UP IN THE QG FIELDS...AND LOW POPS ARE WARRANTED PRIMARILY
ALONG AND NORTH OF THE I 90 CORRIDOR FRIDAY AFTERNOON...LINGERING
IN SOUTHWEST MN FRIDAY EVENING.
THURSDAYS AND FRIDAYS WAVES WILL MARK A SIGNIFICANT PATTERN CHANGE
WHERE NORTHWEST FLOW ALOFT LOOKS TO DOMINATE FOR THE FORESEEABLE
FUTURE. UPPER LOW PRESSURE WILL DOMINATE THE EASTERN HALF OF NORTH
AMERICA WITH UPPER RIDGING THROUGHOUT THE WEST COAST AND EASTERN
PACIFIC. THIS WILL CONTINUE A BROAD NORTHWEST FLOW ALOFT FOR OUR
AREA...WITH PERIODIC UPPER WAVE PASSAGES MOVING DOWN THE WEST SIDE
OF THE EASTERN CANADIAN UPPER LOW. THE DETERMINISTIC MODELS ARE
HAVING THEIR USUAL TIMING DIFFICULTIES THAT FAR OUT WITH REGARDS
TO EXACT FRONTAL TIMING AND PLACEMENT...WHICH IS CRUCIAL FOR
PRECIPITATION CHANCES. HOWEVER THERE DOES NOT APPEAR TO BE A
STRONG CHANCE FOR LIGHT RAINFALL IN ANY GIVEN PERIOD. THEREFORE
CONTINUITY IS IN ORDER IN KEEPING PERIODIC LOW POPS IN PLACE FOR
EARLY NEXT WEEK...AND CHILLY TEMPERATURES THROUGHOUT THE ENTIRE
FRIDAY THROUGH TUESDAY TIME FRAME.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 6228AM CDT WED OCT 16 2013
AREAS OF CEILINGS BELOW 1K FEET AND VISIBILITIES BELOW 3SM JUST
NORTHWEST OF FSD...FROM MADISON TO DE SMET...SHOULD DISSIPATE
BEFORE 16Z. CEILINGS 1-3K FEET OVER NORTHWEST IA TO THE OTG/MJQ/MWM
AREA OF SOUTHWEST MINNESOTA SHOULD IMPROVE TO VFR FROM THE
NORTHWEST BY 16Z. OVER THE REST OF THE AREA THROUGH 16Z AND
OVER ALL OF THE AREA AFTER 16Z THROUGH 17/12Z...VFR CONDITIONS
ARE EXPECTED.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...
LONG TERM...MJ
AVIATION...