933  
FXUS66 KOTX 172339  
AFDOTX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SPOKANE WA  
439 PM PDT SUN JUN 17 2018  
   
SYNOPSIS
 
 
A BREAK IN THE WEATHER IS EXPECTED TODAY WITH TEMPERATURES  
REBOUNDING INTO THE 70S AND 80S. ANOTHER BAND OF RAIN WILL IMPACT  
THE IDAHO PANHANDLE AND SOUTHEASTERN WASHINGTON ON MONDAY. SHOWERS  
WILL PERSIST THROUGH MID WEEK WITH SLOW MOVING AND WET  
THUNDERSTORMS POSSIBLE IN THE AFTERNOON AND EVENING. TEMPERATURES  
WILL PEAK ON WEDNESDAY AND THURSDAY WITH HIGHS IN THE 80S TO LOW  
90S.  
 

 
   
DISCUSSION
 
 
TONIGHT THROUGH TUESDAY NIGHT: LARGE AREA OF LOW PRESSURE REMAINS  
WITHIN CLOSE PROXIMITY TO EASTERN WASHINGTON AND NORTHERN IDAHO  
THROUGH THIS TIME INTERVAL. MOISTURE FEEDING INTO IT AND THE  
CONDITIONALLY UNSTABLE AIRMASS CONTAINED IN IT ALLOW FOR A MENTION  
OF CONVECTION ALONG LOCATIONS THAT BRUSH UP AGAINST THE EDGES OF THE  
LOW OR ARE UNDER IT. MODELS CONTINUE TO HAVE DIFFICULTY IN  
DETERMINING HOW AND WHEN THIS LOW EVENTUALLY MOVES AWAY. AS IT  
STANDS RIGHT NOW GOING INTO TOMORROW THE LARGE LOW WILL KEEP THE  
PRESSURE PATTERN NEAR THE LOWER LEVELS OF THE ATMOSPHERE SET UP IN A  
WAY TO FAVOR NORTH/NORTHEAST WINDS, BREEZY AND GUSTY AT TIMES,  
LINGERING OVER THE FORECAST AREA INTO MONDAY. MINOR DISTURBANCES  
ROTATING IN AND AROUND THE EDGES OF THIS LOW WILL HAVE THE BEST  
POTENTIAL TO BRUSH OVER THE SOUTHEAST PORTION OF THE FORECAST AREA  
THUS SOME MENTION OF CONVECTION REMAINS IN PLACE THERE TONIGHT INTO  
MONDAY. TUESDAY INTO TUESDAY NIGHT DISTURBANCES AND MOISTURE ALONG  
THE NORTHWEST OUTER EDGE OF THE LOW HAVE BETTER POTENTIAL TO  
INFLUENCE A LARGER PORTION OF WASHINGTON AND AS SUCH THE POPS FOR  
SHOWERS AND POSSIBLE THUNDERSTORMS EXTEND FURTHER WEST TO THE  
WASHINGTON CASCADES. THE LARGE LOW PROVIDES A SLOW STORM MOTION SO  
ANY CONVECTION IN THE FORM OF SHOWERS OR THUNDERSTORMS WOULD BE SLOW  
MOVING. FORECAST TEMPERATURES SHOW A GRADUAL WARMING TREND AND ARE A  
BIT ON THE WARM SIDE OF WHAT WOULD BE CONSIDERED NORMAL FOR THIS  
TIME OF YEAR BUT ARE NOT EXCESSIVELY HOT COMPARING THE RECORD HIGH  
TEMPERATURES IN THE BOOKS FOR JUNE 19TH INCLUDE HIGHS OF 97 FOR  
SPOKANE INTERNATIONAL AIRPORT, 96 FOR WENATCHEE PANGBORN AIRPORT,  
AND 98 FOR LEWISTON NEZ PERCE COUNTY AIRPORT. /PELATTI  
 
WEDNESDAY AND THURSDAY: THE WARMEST DAYS OF THE WEEK SHOULD BE WED  
AND THU. THERE IS GOOD AGREEMENT BETWEEN THE MEDIUM RANGE MODELS  
THAT THE UPPER LOW THAT HAS BEEN LANGUISHING OVER THE NORTHERN  
ROCKIES WILL EJECT INTO THE GREAT PLAINS WED AND THU LEAVING A  
FLAT HIGH PRESSURE RIDGE OVER THE WESTERN U.S. AFTERNOON HIGHS ARE  
EXPECTED TO RANGE FROM THE LOW TO MID 80S OVER THE NORTHERN AND  
CENTRAL IDAHO PANHANDLE TO THE UPPER 80S TO LOW 90S FOR THE LOW  
ELEVATIONS OF CENTRAL WASHINGTON. WIDELY SCATTERED SHOWERS AND  
THUNDERSTORMS WILL BE POSSIBLE ON WED AFTERNOON INTO THE NIGHT.  
SURFACE DEWPOINTS ARE EXPECTED TO BE IN THE LOW TO MID 50S AND THE  
MODELS PROG A WEAK UPPER LEVEL DISTURBANCE IN THE VICINITY OF  
CENTRAL/EASTERN WASHINGTON DURING THE HOURS OF PEAK HEATING WED  
AFTERNOON. IF THE MODELS VERIFY, MID AND UPPER LEVEL WINDS WILL BE  
WEAK SUGGESTING THE POTENTIAL FOR SLOW MOVING CELLS CAPABLE OF  
LOCALLY HEAVY RAINFALL. THUNDERSTORM COVERAGE HAS THE POTENTIAL TO  
INCREASE ON THU. THERE ARE MODEL DIFFERENCES WITH THE TRACK AND  
TIMING OF AN INCOMING SHORTWAVE TROUGH. IF THE ECMWF AND CANADIAN  
MODELS VERIFY, THE TROUGH WILL BE OVER THE INLAND NORTHWEST DURING  
THE AFTERNOON AND EVENING SUGGESTING AN ACTIVE DAY FOR SHOWERS AND  
THUNDERSTORMS. ONCE AGAIN, WEAK WINDS ALOFT MAY PRODUCE SLOW  
MOVING CELLS CAPABLE OF HEAVY RAINFALL.  
 
FRIDAY: MODEL DIFFERENCES BECOME INCREASINGLY EVIDENT BY FRI. THE  
GFS AND CANADIAN MODELS HAVE TRENDED DEEPER AND SLOWER WITH A  
TROUGH IN THE FRI AND FRI NIGHT WHILE THE ECMWF IS QUICKER TO  
BUILD A RIDGE BACK OVER THE PACIFIC NORTHWEST. DEEP, SLOW MOVING  
LOWS HAVE BEEN THE NORM THE LAST SEVERAL WEEKS. WITH THAT IN MIND,  
THE GFS AND CANADIAN MAY BE TRENDING IN THE RIGHT DIRECTION. FOR  
NOW, WE ARE FORECASTING AFTERNOON TEMPERATURES TO FALL BACK INTO  
THE UPPER 70S TO MID 80S ON FRI WITH BREEZY WEST WINDS FROM  
CENTRAL WASHINGTON ACROSS THE COLUMBIA BASIN ONTO THE PALOUSE.  
 
SATURDAY AND SUNDAY: A TREND TOWARD A MORE PROGRESSIVE PATTERN IS  
ADVERTISED BY THE ECMWF, GFS, AND CANADIAN MODELS FOR NEXT  
WEEKEND. FLATTER FLOW ACROSS THE PACIFIC AND A BROAD TROUGH OVER  
THE GULF OF ALASKA SUGGESTS A DRIER REGIME. OUR 50 DEGREE  
DEWPOINTS SHOULD BE BLOWN OUT OF THE REGION AS THE WESTERLIES TAKE  
OVER. AT THIS TIME, IT LOOKS LIKE CHANCES FOR SHOWERS WILL  
DECREASE WITH SLIGHTLY WARMER THAN AVERAGE TEMPS FOR NEXT  
WEEKEND. /GKOCH  
 

 
   
AVIATION
 
 
00Z TAFS: LOW PRESSURE TO THE SOUTH OF THE AREA WILL CONTINUE TO  
SEND BANDS OF CLOUDS AND SHOWERS INTO THE AREA. BEST CHANCE OF  
RAIN WILL BE AT KLWS AND KPUW. THERE'S ALSO A THREAT OF  
THUNDERSTORMS AT KLWS MONDAY AFTERNOON. IF ANY HEAVY SHOWERS PASS  
OVER KLWS OR KPUW THEY COULD SEE BRIEF MVFR CONDITIONS. LIGHT  
SHOWERS ARE ALSO POSSIBLE AT KGEG/KSFF/KCOE. KMWH AND KEAT SHOULD  
BE TOO FAR WEST FOR ANY SHOWER ACTIVITY IN THE NEXT 24 HOURS. RJ  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
SPOKANE 58 75 57 81 57 84 / 10 20 20 20 10 10  
COEUR D'ALENE 55 74 55 79 55 81 / 10 40 30 20 20 10  
PULLMAN 55 69 54 75 54 81 / 20 70 50 50 30 10  
LEWISTON 60 75 59 81 59 86 / 30 60 50 40 30 10  
COLVILLE 54 80 55 86 56 88 / 0 10 10 10 10 10  
SANDPOINT 52 73 53 78 53 80 / 10 30 20 20 10 10  
KELLOGG 52 69 51 73 52 80 / 20 60 40 40 20 10  
MOSES LAKE 59 85 58 88 59 91 / 0 10 20 10 10 10  
WENATCHEE 61 86 61 87 65 91 / 10 10 10 10 10 10  
OMAK 56 87 58 88 61 91 / 0 10 10 10 10 10  
 

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

 
 

 
 
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