427  
FXUS66 KPDT 260230  
AFDPDT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PENDLETON OR  
730 PM PDT MON MAR 25 2019  
   
SHORT TERM
 
LARGE UPPER LOW OFFSHORE IS PUSHING A COLD FRONT  
THROUGH THE REGION THIS EVENING INTO THE OVERNIGHT PERIOD. RADAR  
INDICATES PRECIPITATION HAS BEEN INCREASING IN AREAL COVERAGE  
OVER THE PAST FEW HOURS. THIS TREND SHOULD CONTINUE AND EXPECT  
ALL AREAS WILL HAVE SOME RAIN WITH SNOW FOR THE HIGHER MOUNTAINS.  
WINDS HAVE BEEN FAIRLY GUSTY IN MANY LOCATIONS WITH STRONGER WINDS  
ALOFT MIXING DOWN. THIS WILL LIKELY DECREASE LATER TONIGHT. THE  
UPPER LOW REMAINS CENTERED OFFSHORE TUESDAY WITH THE COLD FRONT  
MOVING EAST OF THE REGION BY MORNING. SKIES WILL BE CLEARING.  
ANOTHER FRONT WITH ADDITIONAL RAIN WILL MOVE ACROSS THE FORECAST  
AREA LATE TUE NIGHT AND WEDNESDAY. 94  
 

 
   
PREV DISCUSSION
 
/ISSUED 500 PM PDT MON MAR 25 2019/  
 
SHORT TERM...TONIGHT THROUGH THURSDAY...DEEP AND LARGE UPPER  
LOW/TROUGH OFFSHORE WITH MULTIPLE EMBEDDED WAVES ROTATING AROUND IT  
WILL CONTINUE TO BE THE BIG WEATHER PLAYER FOR THE REGION THROUGH  
THURSDAY. CURRENTLY, A COLD FRONT IS PUSHING INTO THE PACNW AND WILL  
SPREAD VALLEY RAIN/MOUNTAIN SNOW SHOWERS WEST TO EAST ACROSS THE  
AREA THROUGH TONIGHT. THE FRONT DOES NOT HAVE A GOOD MOISTURE FEED  
AND LACKS STRONG UPPER-LEVEL SUPPORT, SO PRECIP AMOUNTS WILL BE  
LIGHT; UP TO 0.25 INCHES OF RAIN WITH 1-3 INCHES OF SNOW POSSIBLE  
ABOVE 4000-5000 FEET. A TIGHT SOUTHERLY GRADIENT FROM THE LOWER  
TREASURE VALLEY TO MEACHAM AND ISENTROPIC DOWNGLIDE WILL CAUSE WINDS  
IN THE GRANDE RONDE VALLEY AND ALONG THE BLUE MOUNTAIN FOOTHILLS TO  
GUSTS TO AROUND 20-35 MPH. WINDS COULD ALSO BE BREEZY IN THE  
COLUMBIA BASIN TONIGHT DURING THE FRONTAL PASSAGE. TUESDAY AND  
TUESDAY NIGHT WILL BE QUIETER, BUT A FEW LINGERING SHOWERS REMAIN  
POSSIBLE IN SE OREGON INTO WALLOWA COUNTY WITH JET SUPPORT OVER  
THE AREA. WEDNESDAY INTO THURSDAY WILL SEE A RETURN TO ACTIVE, WET  
WEATHER ACROSS THE WHOLE CWA AS THE MAIN UPPER-LEVEL LOW/TROUGH  
BEGINS TO PUSH EAST OVER THE PACNW. WARM FRONT WILL LIFT NORTH  
ACROSS THE REGION ON WEDNESDAY/WEDNESDAY NIGHT AND WILL SPREAD  
SHOWERS FROM THE SOUTH. SNOW LEVELS WILL INCREASE TO 5000-5500  
FEET, THEREFORE ANY MODERATE TO HEAVY SNOW WILL OCCUR ALONG THE  
PEAKS OF THE WALLOWAS, ELKHORNS, AND STRAWBERRY MOUNTAINS. THIS  
SYSTEM LOOKS TO BE A BIT WETTER THAN THE PREVIOUS ONE WITH DEEPER  
MOISTURE SOURCE AND STRONGER SUPPORT ALOFT. ALONG WITH THE  
CONTINUED MILDER TEMPS, THIS COULD CONTRIBUTE TO ADDITIONAL  
MOUNTAIN SNOW RUNOFF AND HIGH WATER FLOWS IN AREA RIVERS AND  
STREAMS. THE UPPER-LEVEL LOW WILL THEN WORK OVERHEAD ON THURSDAY  
WITH WIDESPREAD SHOWERS EXPECTED. WITH THE COLD TEMPS ALOFT AND  
MODEST INSTABILITY, A SLIGHT POTENTIAL EXISTS FOR SOME THUNDER  
WEDNESDAY INTO THURSDAY, BUT HAVE KEPT OUT OF THE FORECAST FOR NOW  
AS THE THREAT LOOKS QUITE MARGINAL FOR NOW. SEASONAL TEMPS  
CONTINUE WITH HIGHS IN THE UPPER 40S TO 50S WITH A FEW LOWER 60S  
IN THE LOWER COLUMBIA BASIN. LOWS IN THE UPPER 20S TO 30S WITH A  
FEW LOWER 40S IN THE LOWER COLUMBIA BASIN.  
 
LONG TERM...THURSDAY NIGHT THROUGH MONDAY...THURSDAY NIGHT AN  
UPPER TROUGH WILL BE OVER THE AREA WITH A CLOSED LOW OFF THE OREGON  
COAST. MODELS ARE IN AGREEMENT IN HAVING THE LOW MOVE ASHORE AND  
DISSIPATING EITHER LATE THURSDAY NIGHT (ECMWF) OR FRIDAY (GFS). HAVE  
TRIED TO COMPROMISE BETWEEN THE TWO WITH A CHANCE OF RAIN AND  
MOUNTAIN SNOW ABOVE 4500 FEET THURSDAY NIGHT AND FRIDAY WITH JUST A  
SLIGHT CHANCE OF RAIN IN THE COLUMBIA BASIN. FRIDAY NIGHT THROUGH  
SATURDAY NIGHT RIDGING DEVELOPS AND THIS APPEARS TO BE A BREAK  
BETWEEN SYSTEMS AND HAVE A DRY FORECAST. MODELS BEGIN TO DIVERGE  
SUNDAY BUT IN GENERAL WANT TO BRING ANOTHER SYSTEM INTO THE AREA.  
HAVE BROADBRUSHED A CHANCE OF RAIN AND MOUNTAIN SNOW ABOVE 5000 TO  
6000 FEET FOR SUNDAY THROUGH MONDAY WITH A SLIGHT CHANCE OF RAIN IN  
THE COLUMBIA BASIN. TEMPERATURES WILL BE GENERALLY IN THE 50S AND  
LOWER 60S FRIDAY THROUGH MONDAY. PERRY  
 
AVIATION...00Z TAFS. FRONT MOVING ACROSS THE AREA THIS EVENING AND  
OVERNIGHT WITH PERIODS OF LIGHT RAIN. CEILINGS LOWERING TO 040-080.  
IMPROVING CONDITIONS TUE. LOCALLY BREEZY WINDS 15-25KT THIS EVENING.  
94  
 
HYDROLOGY...AREA RIVER AND STREAM LEVELS ARE STILL A BIT HIGH,  
BUT CONTINUE TO SLOWLY DECREASE. THE GROUND IS STILL QUITE  
SATURATED, BUT THE APPROACHING FRONT TODAY IS NOT EXPECTED TO  
BRING SIGNIFICANT PRECIPITATION AMOUNTS. AS STATED IN THE SHORT-  
TERM DISCUSSION, QPF AMOUNTS WILL BE 0.25 INCH OR LESS. HOWEVER,  
THE QPF TUESDAY NIGHT AND WEDNESDAY WILL REACH 0.25 OR HIGHER IN  
SOME AREAS OF EASTERN OREGON AND FAR SOUTHERN WASHINGTON IN  
ADDITION TO SNOW MELT RUNOFF ASSOCIATED WITH A WARM FRONT. A FEW  
RIVERS TO MONITOR FOR THE NEXT SEVERAL DAYS WILL BE JOHN DAY  
RIVER, UMATILLA RIVER, GRANDE RONDE RIVER, AND WALLA WALLA RIVER.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
PDT 39 57 37 52 / 30 10 10 40  
ALW 42 58 37 54 / 40 10 10 40  
PSC 40 63 37 58 / 30 0 0 30  
YKM 34 60 33 55 / 50 0 0 30  
HRI 40 60 37 55 / 30 10 10 40  
ELN 33 57 30 51 / 60 10 0 20  
RDM 29 55 31 48 / 40 10 20 80  
LGD 37 51 34 50 / 40 30 30 50  
GCD 35 51 37 52 / 30 20 40 80  
DLS 36 59 36 51 / 60 10 10 60  
 

 
   
PDT WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
WA...NONE.  

 
 

 
 
94  
 
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