985  
FXUS66 KOTX 182324  
AFDOTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SPOKANE WA  
424 PM PDT SAT AUG 18 2018  
   
SYNOPSIS
 
 
THIS WEEKEND WILL BE HAZY AND SEASONABLY HOT WITH MOST OF THE  
REGION REACHING THE UPPER 80S TO MID 90S DRY NORTHERLY WINDS WILL  
DEVELOP ON MONDAY RAISING WILDFIRE CONCERNS. TEMPERATURES ARE  
EXPECTED TO COOL THURSDAY AND FRIDAY WITH THE ARRIVAL OF A COLD  
FRONT AND BREEZY WEST WINDS.  
 

 
   
DISCUSSION
 
 
TONIGHT THROUGH MONDAY: SHORTWAVE RIDGING LINGERS THRU MUCH, IF NOT  
ALL OF, TONIGHT WHILE AN AREA OF LOW PRESSURE APPROACHES AND IS  
POSITIONED JUST OFF THE WASHINGTON COAST SUNDAY MORNING. MODELS AT  
THIS POINT IN TIME ARE STILL SUGGESTING SOME POTENTIAL FOR SHORT  
LIVED SPOTTY CONVECTION ALONG THE FAR NORTHEAST FRINGE OF THIS  
INCOMING LOW THAT GETS POSITIONED WITHIN THE VICINITY OF THE EAST  
SLOPES OF THE NORTH CASCADES SUNDAY WITH CONFIDENCE IN THIS SOLUTION  
REMAINING LOW. THE DISCUSSED UPPER LEVEL LOW THEN DRIFTS  
SOUTH/SOUTHEAST WITH A POSITION OVER OREGON AND EXTREME SOUTH  
CENTRAL WASHINGTON MONDAY. AT THE SAME TIME THE LOW SHOWS SOME  
DEEPENING AND INTENSIFICATION ALOFT AND AT THE SURFACE AND FURTHER  
NORTH THE THE OFFSHORE RIDGE OBTAINS A POSITIVE TILT AND FLOPS OVER  
INTO BRITISH COLUMBIA. THIS POSITIONING OF BOTH THE LOW AND THE FLOP  
OVER RIDGE AIDS IN THE INCREASE IN NORTH AND NORTHEAST WINDS ACROSS  
A LARGE PORTION OF EASTERN WASHINGTON AND NORTH IDAHO SUNDAY NIGHT  
INTO MONDAY. FLIES IN THE OINTMENT INCLUDE SOME MODELS SUGGESTING  
SPOTTY HIT AND MISS ELEVATED FORCED CONVECTION FOLLOWED BY A  
TRANSITION TO SURFACE BASED CONVECTION ALONG THE OUTTER EDGES OF THE  
LOW AS SMALL SCALE DISTURBANCES ROTATE COUNTERCLOCKWISE ALONG ITS  
OUTER EDGES. UPPER LEVEL LAPSE RATES ARE QUITE STEEP BETWEEN 700-  
500MB. IT'S HARD TO SEE A GOOD MOISTURE FEED PER PROG PRECIPITABLE  
WATER VALUES BUT PERHAPS THE POSITIONING OF THE UPPER LEVEL LOW  
COULD ALLOW FOR ENOUGH MOISTURE TO SNEAK UP AHEAD AND ALONG ITS  
EASTERN EDGE TO ALLOW SOMETHING IN THE WAY OF SPOTTY CONVECTION TO  
OCCUR. OTHERWISE THE ENHANCED LOW LEVEL NORTH/NORTHEASTERLY WINDS  
FOR MONDAY ARE ACCOMPANIED WITH DRY AIR AT LOW LEVELS AND THERE IS A  
POSSIBILITY THEY MAY NEED TO BE ADDRESSED WITH FIRE WEATHER  
HIGHLIGHTS AS SOME TERRAIN COULD SUPPORT INCREASED FIRE DANGER,  
HOWEVER FOR A GOOD NUMBER OF MOUNTAIN LOCATIONS THIS CHANGE IN WIND  
DIRECTION MAY NOT BE TOO PROBLEMATIC (OTHER THAN THE POTENTIAL FOR  
SPOTTING IN A DIFFERENT DIRECTION) AS FIRE FUELS ON NORTH AND  
NORTHEAST FACING SLOPES ARE OFTEN NOT AS HOT, DRY, AND CAPABLE OF  
SUSTAINING EXCESSIVE FIRE BEHAVIOR IN COMPARISON TO THE HOTTER AND  
DRIER SOUTH AND SOUTHWEST FACING ASPECTS. /PELATTI  
 
TUESDAY: A LOW WILL BE MOVING THROUGH THE OREGON DURING THIS  
PERIOD. THE MODELS ARE IN POOR AGREEMENT ON THE TIME OF PASSING.  
THIS CREATES A DIFFICULT TIME OF DETECTING THE IMPACTS OF THIS  
SYSTEM. THE MODELS HAVE ALSO DECREASED THE AMOUNT OF MOISTURE  
ASSOCIATED WITH THIS SYSTEM. WITH A DECREASING PRESSURE GRADIENT  
ON TUESDAY, THE WINDS WILL SLOW THROUGHOUT THE DAY. A LINE OF  
INSTABILITY IS HIGHLIGHTED ALONG THE WASHINGTON OREGON BORDER AND  
COULD DEVELOP INTO ISOLATED THUNDERSTORMS DURING THE DAYTIME  
PERIODS. HIGHS ARE EXPECTED TO BE IN THE 80S TO LOW 90S.  
 
WEDNESDAY: THE LOW IS EXPECTED TO PUSH THROUGH ON WEDNESDAY. THE  
GFS IS CARRYING MORE INSTABILITY THROUGH THE INLAND NORTHWEST THEN  
THE ECMWF. THE LOW AGREEMENT BETWEEN THE MODELS KEPT ANY MAJOR  
CHANGES FROM PREVIOUS FORECAST FROM OCCURRING. THUNDERSTORMS ARE  
MAINLY IN THE IDAHO PANHANDLE AND CASCADES. A WIND SHIFT FROM THE  
NORTHEAST TO SOUTH. THIS IS EXPECTED TO BRING MORE SMOKE AND HAZE  
INTO THE REGION AND LEAD TO ANOTHER PERIOD OF SMOKE AND HAZE FROM  
FIRES TO THE SOUTH OF WASHINGTON. HIGHS ARE EXPECTED TO BE IN THE  
80S TO LOW 90S  
 
THURSDAY AND FRIDAY: BY THURSDAY, THE REGION WILL BE A ZONAL FLOW  
PATTERN WITH A QUICK MOVING TROF PATTERN. THE WESTERLY FLOW  
PATTERN IS EXPECTED TO BRING BETTER AIR QUALITY TO THE REGION. IT  
WILL ALSO BRING COOLER AND MORE MOIST AIR INTO THE REGION.  
TEMPERATURES ARE EXPECTED TO BE COOLER THAN EARLIER IN THE WEEK,  
BUT STILL BE IN THE 80S. /JDC  
 

 
   
AVIATION
 
 
00Z TAFS: WILD FIRE SMOKE IS MOVING INTO THE AREA FROM THE NORTH  
CASCADES AS WELL AS SOUTHERN BC. NORTHERLY WINDS WILL CONTINUE  
THIS FLOW OF SMOKE INTO ALL OF THE TAF SITES. PREDICTIVE SKILL IS  
LOW FOR WHERE SMOKE WILL GO AND WHAT VISIBILITIES WILL RESULT. THE  
GENERAL THINKING IS THAT VISIBLITIES WILL BE LOWEST OVERNIGHT AND  
SUNDAY MORNING, AND THEN IMPROVE SOME IN THE AFTERNOON. RJ  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
SPOKANE 59 91 62 84 59 87 / 0 0 0 0 0 0  
COEUR D'ALENE 56 90 58 83 56 87 / 0 0 10 10 0 0  
PULLMAN 53 90 58 85 54 86 / 0 0 0 10 20 0  
LEWISTON 61 96 64 91 62 93 / 0 0 10 10 20 0  
COLVILLE 52 92 55 87 52 91 / 0 0 0 0 0 0  
SANDPOINT 53 87 53 80 50 85 / 0 10 10 10 0 0  
KELLOGG 54 87 55 79 52 84 / 0 10 10 10 0 0  
MOSES LAKE 55 94 62 92 60 92 / 0 0 0 0 0 0  
WENATCHEE 63 93 65 91 65 90 / 0 0 0 0 0 0  
OMAK 61 94 61 91 60 92 / 0 0 0 0 0 0  
 

 
   
OTX WATCHES/WARNINGS/ADVISORIES
 
 
ID...NONE.  
WA...NONE.  
 

 
 

 
 
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