126  
FXCN01 CWAO 160900  
 
DAYS 4 TO 7 SIGNIFICANT WEATHER DISCUSSION WITH UPDATE TO THE DAYS 1 TO 3 - WEST  
 
UPDATE TO THE DAYS 1 TO 3 DISCUSSION - WEST  
 
NO UPDATE NECESSARY.  
 
DAYS 4 TO 7 SIGNIFICANT WEATHER DISCUSSION - WEST  
VALID 00Z THURSDAY JULY 19 2018 - 00Z MONDAY JULY 23 2018  
 
CONVECTIVE INVERTED TROUGH OVER AB THURSDAY AND MOVING EASTWARD..  
PREFERRED GUIDANCE: GDPS.  
SCENARIO CONFIDENCE LEVEL: MEDIUM.  
ALL GUIDANCE ARE IN GOOD AGREEMENT TO SLIDE EASTWARD THE INVERTED SURFACE  
TROUGH ACROSS THE PRAIRIES, WHERE CONVECTION ARE FORECAST TO DEVELOP HERE AND  
THERE INTO THE WIDE SURFACE TROUGH. MODELS BEGIN TO DIFFER WITH TIMING BEYOND  
22/00Z WHERE GEPS MOVE THE TROUGH FASTER TOWARDS EASTERN PRAIRIES WHILE ECMWF  
IS ON THE SLOW SIDE, BUT NOT SO MUCH FROM THE CONSENSUS. DESPITE OF THE SMALL  
DIFFERENCE BY END OF THE PERIOD, THERE IS NO REASON TO REJECT THE GDPS.  
 
GDPS CYAN, GEPS YELLOW, GFS RED, NAEFS GREEN, ECMWF GREY.  
[HTTP://COLLABORATION.CMC.EC.GC.CA//CMC/CMOP/FXCN/20180716/IMAGES/200_MULTI_2018071600Z_144HR_CENTRE.JPG]  
 
HIGH ARCTIC..  
PREFERRED GUIDANCE: ECMWF.  
SCENARIO CONFIDENCE LEVEL: LOW..  
MODELS ARE FAR FROM AGREEMENT HERE WITH A SYSTEM FORECAST TO SWEEP THE HIGH  
ARCTIC. THE GDPS ON THE FAST SIDE IS AN EASY OUTLIER HERE, WHILE THE ECMWF SHOW  
SIMILAR TRACK THAN THE GDPS, BUT SLOWER. THE GEPS GIVE SOME SUPPORT TO THE  
ECMWF, BUT IS WEAKER DUE TO THE SPREAD OF INDIVIDUAL MEMBERS. HOWEVER, THE GDPS  
PARALLEL RUN SEEMS GIVING SOME SUPPORT TO THE ECMWF TO FORECAST A SLOWER  
SOLUTION THAN THE GDPS OPERATIONAL.. HENCE WITH LOW CONFIDENCE, WE OPT FOR THE  
ECMWF, AND WE WON'T BE SURPRISE TO SEE THE GDPS TO CONVERGE TOWARDS THAT  
SOLUTION.  
 
 
THE COMPLETE VERSION OF THIS DISCUSSION IS AVAILABLE AT THE FOLLOWING LINK:  
[HTTP://COLLABORATION.CMC.EC.GC.CA/CMC/CMOP/FXCN/20180716/FX_D4-7_WEST_2018071600.HTML]  
 
END/CHENARD  
 
 
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