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Displaying AFOS PIL: AFDFSD Received: 2014-07-29 17:20 UTC
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538 FXUS63 KFSD 291720 AFDFSD AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SIOUX FALLS SD 1220 PM CDT TUE JUL 29 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 334 AM CDT TUE JUL 29 2014 COOL HIGH PRESSURE IN CONTROL EARLY THIS MORNING...WITH A FEW RANDOM PATCHES OF MID CLOUDS IN THE JAMES VALLEY...AND SOME RAGGED CIRRUS ROTATING INTO THE REGION ON THE EDGE OF THE SUBTROPICAL PLUME THROUGH THE ROCKIES. ALL BUT ASSURED TO SEE ADDITIONAL CUMULUS DEVELOP WITH THE DIURNAL CYCLE TODAY...BUT LAYER IS QUITE THIN COMPARED TO YESTERDAY...SO QUICK FORMATION AND A FASTER THAN TYPICAL ENTRAINMENT AIDED DISSIPATION ARE PROBABLY IN ORDER. TEMPS WILL BE 2-4 DEGREES WARMER THAN TUESDAY BASED ON TRENDS AT 850/925 HPA...MID 70S TO LOWER 80S EXPECTED. THERE IS A VERY SUBTLE CONVERGENCE BOUNDARY IN SEVERAL SOLUTIONS WHICH PUSHES SOUTHWARD FROM NORTH DAKOTA INTO SOUTH DAKOTA TONIGHT...AND A ROGUE SOLUTION OR TWO THAT SUGGEST AN ISOLATED SHOWER OR THUNDERSTORM COULD WANDER TOWARD THE NORTHWESTERN CWA LATER IN THE NIGHT. WITH LARGER SCALE LESS THAN HELPFUL TO SUSTAINED LIFT...HAVE CHOSEN TO IGNORE ANY THREAT FOR NOW...AND JUST PUT A FEW MORE CLOUDS INTO THE WEST AFTER EVENING CLEARING. LOWS UNDER LOW LEVEL RIDGE AXIS LIKELY AGAIN TOWARD THE LOWER SIDE OF GUIDANCE ENVELOPE. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 334 AM CDT TUE JUL 29 2014 AN EXTENDED PERIOD OF DRY AND PLEASANT WEATHER IS EXPECTED AT LEAST THROUGH THE END OF THE WEEK. A WELL AMPLIFIED BLOCKING PATTERN WILL ALLOW VERY LITTLE CHANGE IN THE UPPER LEVEL PATTERN DURING THIS TIME WITH COOL NORTHWEST UPPER FLOW REMAINING THE NORM. WEAK LOW LEVEL FLOW WILL ALSO RESULT IN AN EXTENDED PERIOD OF UNUSUALLY LIGHT WINDS...GENERALLY LESS THAN 10 MPH AND OFTEN LIGHT AND VARIABLE AT THE SURFACE. DIURNALLY DRIVEN SCATTERED CUMULUS WILL POP UP WITH THE HEAT OF THE DAY...HOWEVER AM NOT EXPECTING ANY MEASURABLE PRECIPITATION WITH VERY WEAK FORCING AND DRY LOWER LEVELS. THE GFS AND NAM ARE PICKING UP ON VERY SPOTTY SHOWERS OR SPRINKLES LATE WEEK...BUT CONFIDENCE IN ANY MEASURABLE REACHING THE GROUND IS LOW ENOUGH AT THIS TIME TO LEAVE OUT ANY MENTION. WITH A DECENT AMOUNT OF SUNSHINE...MIXING SHOULD BE DECENT ENOUGH TO CONTINUE FOLLOWING SOME OF THE WARMER GUIDANCE FOR DAYTIME TEMPERATURES. A VERY SUBTLE WARMING TREND CAN BE EXPECTED...BUT NOT MORE THAN A FEW DEGREES THROUGH THE ENTIRE PERIOD. HIGHS WILL BE IN THE UPPER 70S TO MID 80S...PERHAPS APPROACHING 90 IN SOUTH CENTRAL SD BY THE WEEKEND. MODELS ARE NOW COMING INTO SLIGHTLY BETTER AGREEMENT IN FINALLY BREAKING DOWN THE PATTERN EARLY NEXT WEEK. THE GFS IS QUITE A BIT MORE BULLISH IN DRIVING A TROUGH INTO THE NORTHERN PLAINS SUNDAY AFTERNOON THROUGH AND MONDAY WITH A TRAILING FRONT BECOMING STALLED NEAR THE MISSOURI RIVER INTO AT LEAST MONDAY NIGHT. THE ECMWF IS MUCH SLOWER IN PROGRESSION...THEREFORE PRECIPITATION CHANCES REMAIN LOW END AT THIS TIME WITH LOW CONFIDENCE IN THE TIMING OF THIS SYSTEM. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 1217 PM CDT TUE JUL 29 2014 VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. JUST SOME DIURNAL SCATTERED TO BROKEN CU BASED AROUND 5000 TO 6000 FEET THROUGH THIS AFTERNOON...WITH SOME LINGERING MID LEVEL CLOUDS POSSIBLE OVERNIGHT OUT WEST. COULD ALSO SEE SOME PATCHY AREAS OF SHALLOW FOG FOR A BRIEF PERIOD WEDNESDAY MORNING...SIMILAR TO WHAT WE SAW THIS MORNING. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...CHAPMAN LONG TERM... AVIATION...CHENARD