830  
FXUS63 KFSD 172301  
AFDFSD  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SIOUX FALLS SD  
601 PM CDT SUN JUN 17 2018  
   
SHORT TERM
 
(THIS EVENING THROUGH MONDAY NIGHT)  
ISSUED AT 351 PM CDT SUN JUN 17 2018  
 
AT THIS TIME, LEADING EDGE OF THE SURFACE COLD FRONT EXTENDS FROM  
NEAR REDWOOD FALLS MN, SOUTHWESTWARD BISECTING THE SIOUX FALLS CWA,  
AND TO JUST EAST OF AINSWORTH NE. ALOFT, WE STILL HAVE OUR LARGE  
BLOCKING UPPER RIDGE CENTERED OVER THE GULF COAST STATES. TONIGHT,  
NOT AT ALL CONFIDENT ANYMORE THAT A SHORT WAVE WILL MOVE THROUGH  
THIS AREA, UNLESS IF ITS CONVECTIVELY DEVELOPED. THE REMNANTS OF BUD  
REALLY DID NOT SURVIVE ITS TRACK OVER THE CENTRAL ROCKIES, SO WE ARE  
LEFT WITH MID LEVEL HEIGHTS WHICH ARE ACTUALLY SLIGHTLY RISING. AS  
THE UPPER RIDGE BREAKS DOWN A TAD, WE DO COOL OFF IN THE MID LEVELS  
AS THE NIGHT PROGRESSES. SOUNDING PROFILES SHOW A LAPSE RATE WHICH  
IS NOT OVERLY UNSTABLE WITH FAIRLY THIN CAPE VALUES. SHEAR IS  
MARGINAL WITH WIND SPEEDS IN THE MID LEVELS ONLY ABOUT 25 KNOTS. AS  
THE LOW LEVEL BOUNDARY OOZES SOUTHWARD, CORFIDI VECTORS ARE LARGELY  
ORIENTATED PARALLEL WITH THE WIND SHIFT. SO ALL SAID, NOT TOO  
CONCERNED ABOUT SEVERE WEATHER POTENTIAL ANYMORE. HOWEVER WE DO  
STILL HAVE A THREAT FOR POCKETS OF HEAVY RAINFALL IF TSRA HAPPENS TO  
TRAIN OVER THE SAME AREAS FOR A FEW HOURS. GOES 16 WATER VAPOR  
IMAGERY SHOWS A STRIPE OF ENHANCED MOISTURE STREAMING NORTHWARD FROM  
CENTRAL MEXICO, ACROSS THE WESTERN PLAINS AND BENDING INTO OUR  
WESTERN ZONES. BUT THE DEEP RICH TROPICAL MOISTURE WHICH THE  
REMNANTS OF BUD PROVIDED APPEARS TO BE LARGELY ABSENT. SO WIDESPREAD  
HEAVY RAIN MAY NOT BE A HUGE THREAT ANYMORE.  
 
ONE BIG QUESTION IS WHERE HEAVY RAINFALL MAY OR MAY NOT OCCUR. THE  
PLACEMENT OF IT IS EXTREMELY TRICKY TONIGHT. THE ECMWF AND NAM KEEP  
THE HEAVIEST PRECIP JUST NORTH OF I 90, TRAILING A BIT SOUTHWESTWARD  
INTO OUR SOUTH CENTRAL SD ZONES. THIS IS RIGHT ALONG THE 925-850MB  
FRONT AND THIS SCENARIO IS PLAUSIBLE AS CONVECTION WILL BE ELEVATED  
TONIGHT. MANY OF THE VARIOUS CAMS HAVE THE HEAVIEST PRECIP FURTHER  
SOUTH, PRIMARILY EXTENDING FROM THE YANKTON AREA, NORTHEASTWARD TO  
THE SOUTHERN SECTIONS OF SOUTHWEST MINNESOTA. THIS SCENARIO WOULD  
HAPPEN IF THE COLD POOL TAKES OVER A BIT AND PUSHES THE TSRA A BIT  
FURTHER SOUTHWARD FROM THE ELEVATED FRONT. THEREFORE HAVE LIKELY TO  
CATEGORICAL POPS PROBABLY IN A WIDER NORTH TO SOUTH EXTENT THEN WHAT  
MAY HAPPEN IN REALITY, BUT CHOSE TO DO THIS TO COVER THE TWO  
DIFFERENT SCENARIOS. POPS SHOULD BE PRETTY HIGH IN OUR NORTH ANYWAY  
BECAUSE EVEN IF THAT AREA DOES MISS THE HEAVIEST OF RAINFALL, THE  
CHANCES OF OUR NORTHERN ZONES RECEIVING RAIN OUR VERY GOOD. THE ONE  
EXCEPTION IS IN OUR FAR NORTHWEST NEAR HURON, WHERE ALL SOLUTIONS  
SHOW MUCH OF THE ACTIVITY SOUTH OF. FOR QPF, PUT MORE STOCK IN THE  
CAMS AT THIS TIME AND HAVE THE HEAVIEST PRECIP FROM SOUTHEAST SD, TO  
EXTREME NORTHWEST IA AND THE SOUTHERN SECTIONS OF SOUTHWEST MN. BUT  
AGAIN, NOT REAL CONFIDENT OF THAT SO HATE TO SPECULATE ON WHAT EXACT  
AMOUNTS MAY BE OTHER THAN ONE TO THREE INCHES, WITH THE HEAVIER  
AMOUNTS UNDER TRAINING ECHOES.  
 
THE ACTIVITY SLOWLY WANES AFTER MIDNIGHT. THEN ON MONDAY AND MONDAY  
NIGHT, THE LARGE UPPER LOW TO THE WEST NUDGES EVER SO SLOWLY  
EASTWARD INTO THE INTERMOUNTAIN WEST. A SHORT WAVE MOVES EASTWARD  
AHEAD OF THIS LOW THROUGH OUR AREA LATE MONDAY AFTERNOON AND NIGHT.  
THE LOW LEVEL BOUNDARY KIND OF STALLS IN NORTHWEST IA NEAR THE SIOUX  
CITY AREA LATE TONIGHT AND MONDAY. THEREFORE HAVE AN AREA OF  
ENHANCED POPS DRAWN JUST NORTH OF THAT BOUNDARY MONDAY AFTERNOON  
FROM SPENCER IA, TO YANKTON AND LAKE ANDES SD. THEN THE SHORT WAVE  
INTERACTION MONDAY NIGHT KEEPS POPS PRETTY HIGH ACROSS THE AREA.  
CONCERNING TEMPERATURES, IT WILL BE COOLER FOR MANY AREAS ON MONDAY  
BUT STILL QUITE WARM AND HUMID NEAR THE STALLED FRONTAL BOUNDARY  
FROM SIOUX CITY TO STORM LAKE WHERE MID 80S SHOULD PREVAIL.  
   
LONG TERM
 
(MONDAY NIGHT THROUGH SUNDAY)  
ISSUED AT 351 PM CDT SUN JUN 17 2018  
 
FOR THE REST OF THE WEEK, THE AFOREMENTIONED UPPER LOW BEGINS TO  
MOVE EASTWARD FROM THE INTERMOUNTAIN WEST AND INTO THE PLAINS  
BEGINNING ON WEDNESDAY. THERE IS MODEL CONSENSUS THAT THE LOW THEN  
SOMEWHAT CLOSES OFF AS IT MOVES EASTWARD ON THURSDAY AND FRIDAY.  
INITIALLY TUESDAY NIGHT THROUGH WEDNESDAY NIGHT, THE HIGHER POPS  
STILL FAVOR OUR WESTERN AND SOUTHERN ZONES WITH SHOWERS AND EMBEDDED  
TSRA, AS AN EASTERLY FETCH OF LOW LEVEL AIR STABILIZES AND GIVES A  
DRIER AIR MASS TO OUR EASTERN ZONES. BUT ON THURSDAY AND THURSDAY  
NIGHT, THE CHANCES FOR RAIN BECOMES MORE UNIFORM ACROSS THE  
ENTIRE FORECAST AREA AS THE UPPER LOW CLOSES OFF AND SPINS VERY  
NEAR OUR AREA. SO IT IS RATHER UNSETTLED THIS ENTIRE WEEK, NOT  
TOO UNCOMMON FOR MID JUNE TYPE WEATHER. FROM TUESDAY THROUGH  
FRIDAY, THE UNSETTLED PATTERN AND UPPER LOW WILL PRODUCE HIGHS  
ONLY IN THE 70S, WITH PERHAPS A MODEST WARM UP FOR THE WEEKEND AS  
THE UPPER LOW PULLS EASTWARD.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)  
ISSUED AT 557 PM CDT SUN JUN 17 2018  
 
A FRONTAL BOUNDARY WILL PUSH SLOWLY ACROSS THE REGION, BRINGING A  
THREAT OF SHOWERS AND THUNDERSTORMS FOR TONIGHT. RAIN COULD BE  
HEAVY AT TIMES IN STRONGER STORMS. AS THE FRONT MOVES TO THE  
SOUTHEAST, MVFR CEILINGS WILL FILL IN BEHIND THE FRONT AND  
PERSIST INTO MONDAY.  
 

 
   
FSD WATCHES/WARNINGS/ADVISORIES
 
 
SD...NONE.  
MN...NONE.  
IA...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR IAZ002-003-012>014-  
020>022-031-032.  
 
NE...HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NEZ014.  
 

 
 

 
 
SHORT TERM...MJ  
LONG TERM...MJ  
AVIATION...JM  
 
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