611  
FXUS63 KBIS 221004  
AFDBIS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BISMARCK ND  
504 AM CDT SUN OCT 22 2017  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
 
ISSUED AT 445 AM CDT SUN OCT 22 2017  
 
FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE MILD AND  
BREEZY CONDITIONS TODAY FOLLOWED BY COLD FRONTAL PASSAGES TONIGHT  
AND RESULTANT STRONG WINDS.  
 
CURRENTLY, UPPER LEVEL TROUGH MOVING OFF TO OUR EAST WITH A  
SUBTLE SW/V MID LEVEL RIDGE MOVING INTO THE DAKOTAS. SUBSIDENCE  
UNDERNEATH THE RIDGE RESULTS IN A CLEAR SKY OVER WESTERN AND  
CENTRAL NORTH DAKOTA AT THE MOMENT ALONG WITH WEAK PRESSURE RISES  
CONTRIBUTING TO A STEADY WEST/SOUTHWEST WIND. DESPITE THE MIXING  
TEMPERATURES HAVE DROPPED INTO THE UPPER 20S TO LOWER 30S OVER  
AREAS OF WESTERN ND WITH VERY DRY AIR IN PLACE.  
 
FOR TODAY, A WEAK WARM FRONT WILL MOVE EAST ACROSS THE AREA  
QUICKLY FOLLOWED BY A POTENT EMBEDDED SW/V TROUGH. BOUNDARY LAYER  
WAA ACROSS THE SOUTH WILL COMBINE WITH A BREEZY SOUTHWEST FLOW TO  
HELP TEMPERATURES WARM INTO THE 60S SOUTH. 50S NORTH WHERE  
TEMPERATURE ADVECTION WILL BE NEAR ZERO. BUFKIT ANALYSIS INDICATES  
WINDS TODAY SHOULD REMAIN SUB-ADVISORY WITH 30-35KTS WITHIN THE  
MIXED LAYER AT MOST SO NO HEADLINES ARE PLANNED FOR THE TODAY  
PERIOD. INCREASING CLOUDS AHEAD OF THE WAVE AFTER 12Z WITH MOST  
AREAS WITH THE EXCEPTION OF PARTS OF THE JAMES RIVER VALLEY  
CLOUDED OVER BY 18Z. LEFT EXIT REGION UPPER JET DYNAMICS PUSHING  
INTO THE NORTHERN PLAINS COUPLED WITH MOISTURE ADVECTION WEST TO  
EAST SHOULD CONTRIBUTE TO LIGHT RAIN DEVELOPMENT ACROSS MY  
COUNTIES LATER THIS MORNING AND AFTERNOON ONCE CIGS LOWER TO BELOW  
10K FT AGL. CHANCES DECREASE SUNDAY EVENING WHEN MODELS DIMINISH  
JET FORCING AND MOISTURE.  
 
FOR TONIGHT, PRIMARY COLD FRONT SWEEPS EAST ACROSS WESTERN AND  
CENTRAL ND THIS EVENING MAINTAINING A STEADY AND BREEZY WESTERLY  
WIND. SECONDARY COLD FRONT THEN MOVES INTO NORTHWEST/NORTH CENTRAL  
ND AFTER 08Z ACCOMPANIED BY A STRONG EMBEDDED MID LEVEL IMPULSE.  
THIS SECONDARY FROPA WILL BE ACCOMPANIED BY A MODERATELY STRONG  
PRESSURE RISE BUBBLE WITH 3-HR PRESSURE RISES 4-8MB (NAM/GFS/HIGH  
RES EC) MOVING INTO MY NORTH AFTER 08Z AND CONTINUING SOUTH-  
SOUTHEAST BEFORE WASHING OUT MID MORNING MONDAY. TWO RECENT EVENTS  
DURING THE NIGHTTIME WE HAD 10MB 3 HOUR RISES CONTRIBUTED TO WIND  
GUSTS WELL OVER 45 MPH. DIFFERENCE THIS TIME AROUND WE NOTICED IS  
THE PRESSURE SURGE WILL BE ACCOMPANIED BY STRONGER CAA AND  
STEEPER LAPSE RATES WHICH WOULD CONTRIBUTE TO DEEPER MIXING. WIND  
ADVISORY VALUES SHOULD EASILY BE REACHED WITH THIS PRESSURE RISE  
BUBBLE, WITH NAM/GFS BUFKIT EVEN HIGHER ADVERTISING 50-55KTS  
WITHIN THE MIXED LAYER. OPTED TO HOIST A HIGH WIND WATCH FROM  
08-15Z MONDAY MORNING ACROSS THE NORTH AND CENTRAL.  
 
MID LEVEL IMPULSE DRIVING THE SECONDARY COLD FRONT WILL ALSO BRING  
A CHANCE FOR RAIN AND LOW LEVEL CLOUDS INTO THE NORTH LATE TONIGHT  
THEN SOUTH-SOUTHEASTWARD THROUGH MONDAY AM. ANY PRECIPITATION  
COULD ALSO INCREASE THE MIXING POTENTIAL FOR STRONGER WINDS TO  
REACH THE SURFACE.  
 
   
LONG TERM
 
(MONDAY THROUGH SATURDAY)  
 
ISSUED AT 445 AM CDT SUN OCT 22 2017  
 
ACTIVE PATTERN PREVAILS IN THE LONG TERM PERIOD.  
 
TIGHT PRESSURE GRADIENT DURING THE DAY MONDAY WILL SEE STRONG  
NORTHWEST WINDS ACROSS THE REGION. HIGHEST WINDS ARE ADVERTISED  
ACROSS THE HIGHER TERRAIN OF THE SOUTHWEST WHERE BUFKIT IS NEAR  
HIGH WIND WARNING CRITERIA. ADDITIONAL WIND HEADLINES ARE THUS  
LOOKING LIKELY FOR MONDAY ACROSS MUCH OF WESTERN AND CENTRAL NORTH  
DAKOTA DURING THE DAY. ONGOING PRECIPITATION MONDAY MORNING SHOULD  
DIMINISH INTO THE DAY AS FORCING DECREASES.  
 
UPPER LEVEL RIDGE OVER THE WESTERN CONUS TRIES TO REBUILD  
EASTWARD TUESDAY NIGHT INTO WEDNESDAY. SOME WAA ON TUESDAY WILL  
SEE MILD TEMPERATURES TRY TO MOVE BACK INTO OUR AREA. ON WEDNESDAY  
A SUBTLE MID LEVEL RIDGE AND SURFACE HIGH PRESSURE WILL BE OVER  
THE DAKOTAS. EXPECT A TIGHT TEMPERATURE GRADIENT WITH LOW 50S IN  
THE NORTHEAST PART OF THE STATE AND 60S SOUTHWEST.  
 
WE CONTINUE TO WATCH CLOSELY THE WED NIGHT/THURSDAY (AND ONWARD?)  
TIME PERIOD CLOSELY. VIGOROUS SW/V DIVING EAST-SOUTHEAST FROM  
SOUTHWEST CANADA WED AFTERNOON INTO THE NORTHERN PLAINS WEDNESDAY  
NIGHT WILL BRING A STRONG SURFACE LOW/COLD FRONT ACROSS THE  
DAKOTAS WED NIGHT/THURSDAY. BOTH THE GFS AND ECMWF REMAIN IN  
AGREEMENT WITH THIS THOUGH THERE STILL REMAIN SUBTLE DIFFERENCES  
ON TIMING AND PLACEMENT OF THE LOW. STRONG CAA/GRADIENT FORCING  
WILL LIKELY RESULT IN A PERIOD OF STRONG WINDS DURING AND AFTER  
THE FROPA.  
 
BOTH MODELS SUGGEST A RAIN TO SNOW CHANGEOVER LATE WED NIGHT INTO  
THE DAY THURSDAY FROM NORTH TO SOUTH WHEN TEMPERATURES ALOFT  
BECOME SUBZERO. BLENDED MODELS HAVE COOLED TEMPERATURES THE LAST  
TWO DAYS NOW, WITH DAYTIME HIGHS THURSDAY NOW IN THE 30S WEST AND  
NORTH AND 40S ELSEWHERE. ANOTHER DROP WOULD NOT BE SURPRISING.  
 
BIGGEST DIFFERENCE BETWEEN THE GFS/ECMWF IS THE EVOLUTION OF THE  
SW/V AS IT MOVES INTO THE NORTH CENTRAL CONUS. THE GFS HAS  
CONSISTENTLY BEEN MORE PROGRESSIVE KEEPING THIS FEATURE AN OPEN  
WAVE AND TAKING ALL FORCING TO OUR EAST BY FRIDAY. THE EC THE PAST  
COUPLE RUNS MORPHS THE SW/V INTO A CLOSED LOW OVER THE NORTHERN  
PLAINS AND MAINTAINS PRECIPITATION THROUGH THE END OF THE WORK  
WEEK. THE EC IS ALSO COLDER AND THUS PUTS MODERATE ACCUMULATING  
SNOW ACROSS MY NORTHEAST. WE WILL CONTINUE TO WATCH THIS SYSTEM  
CLOSELY AND WILL ALSO CONTINUE TO MENTION IN THE HWO AND SOCIAL  
MEDIA.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)  
 
ISSUED AT 102 AM CDT SUN OCT 22 2017  
 
VFR CONDITIONS ARE EXPECTED. HAZARDS TO AVIATION INCLUDE LLWS  
AT ALL TAF SITES. GUSTY SOUTHWEST WINDS TODAY WILL USHER IN WARMER  
CONDITIONS AND MID LEVEL CLOUDS ACROSS THE TAF SITES TODAY. WINDS  
WILL INCREASE SUNDAY EVENING INTO MONDAY AHEAD OF A COLD FRONT  
THAT WILL PUSH SOUTHEAST ACROSS OUR AREA SUNDAY NIGHT.  
 

 
   
BIS WATCHES/WARNINGS/ADVISORIES
 
 
HIGH WIND WATCH FROM LATE TONIGHT THROUGH MONDAY MORNING FOR  
NDZ001>005-009>013-017>023-034>036.  
 

 
 

 
 
SHORT TERM...NH  
LONG TERM...NH  
AVIATION...JV  
 
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