219  
FXCN01 CWAO 181000  
 
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 TUESDAY NOVEMBER 21 2017 - 00Z SATURDAY NOVEMBER 25 2017  
 
SURFACE LOW OVER EASTERN PRAIRIES MOVING ACROSS ONTARIO BY 21/12Z INTO HUDSON  
BAY ON WEDNESDAY (22/12Z)...  
PREFERRED GUIDANCE: GEPS MEAN (GDPS A BIT TOO DEEP/SLOW)  
SCENARIO CONFIDENCE LEVEL: MEDIUM  
GDPS REMAIN ON DEEP SIDE TO THE WEST OF CONSENSUS MADE BY THE GEPS MEAN  
SOLUTION WHICH IS MORE IN LINE WITH GFS/NAEFS/ECMWF. GDPS KEEP THIS DEEPER REND  
AS THE SYSTEM IS MOVING ACROSS JAMES BAY/NORTHERN QC ON TUESDAY (23/00Z) AND  
MERGING WITH THE HUDSON BAY SYSTEM ON THURSDAY (23/12Z). ON FRIDAY ECMWF SEEM  
SUSPICIOUS WITH A DEEP SURFACE LOW JUST WEST OF LABRADOR BUT SEEM FINE ON  
SATURDAY (25/00Z) WHILE THE GDPS REMAIN A BIT ON THE NORTH AS THE SYSTEM IS  
SPINNING OVER THE HUDSON BAY AND WEAKENING BY SATURDAY (25/00Z).  
 
OFFSHORE BC BROAD SURFACE TROUGH WITH EMBEDDED SURFACE LOWS...  
PREFERRED GUIDANCE: GDPS ( GDPS UNTIL FRIDAY (24/12Z) AND GEPS MEAN ON SATURDAY)  
SCENARIO CONFIDENCE LEVEL: MEDIUM  
NO SIGNIFICANT DIFFERENCE WITH THE GDPS SOLUTION UNTIL 00Z ON WEDNESDAY  
(22/00Z). THE NEW GFS 00Z DEEPEN THE THE NORTHEASTERN QUADRANT OF THE  
ASSOCIATED UPPER LOW WHICH KEEP THE POSITION SURFACE FEAT TO THE NORTH/NORTHEAST  
WHICH IS MORE TO THE NORTHEAST OF GDPS WHICH IS MORE IN LINE WITH  
GEPS MEAN/UKMET AND EVEN WITH THE ECMWF WHICH IS A BIT TO THE NORTH BUT NOT  
BY MUCH. ON THURSDAY 23/00Z THE DIFFERENCE BETWEEN MODELS BECOME LARGER AS  
THE SYSTEM IS SPINNING AND WEAKENING ALONG THE HAIDA GWAII AREA AS THE  
SYSTEM SEEM TO MOVE INLAND TO DEVELOP ANOTHER SURFACE LOW OVER AB ON FRIDAY  
(24/00Z AND 24/12Z) AS THE SURFACE LOW IS DEEPENING OVER AB...GDPS REMAIN QUITE  
SIMILAR TO THE 12Z GDPS RUN MOVING THE SYSTEM ACROSS CENTRAL PRAIRIES INTO  
EASTERN PRAIRIES AND AFFECTING WESTERN ON. BY SATURDAY (25/00Z) THE GDPS SEEM ON  
DEEP SIDE WITH THE ASSOCIATED UPPER TROUGH SHOWING DEEP SURFACE LOW OVER  
WESTERN ON IN VICINITY AB BORDER WHILE GEPS MEAN PUSH SYSTEM JUST TO THE  
NORTH OF LAKE SUPERIOR JUST LIKE THE ECMWF/GFS.  
 
SYSTEM DEVELOPING OVER THE GULF OF ALASKA ON FRIDAY (24/12Z)...  
PREFERRED GUIDANCE: GDPS  
SCENARIO CONFIDENCE LEVEL: MEDIUM  
GDPS SOLUTION IS IN GOOD AGREEMENT WITH GFS/GEPS MEAN WITH THIS SYSTEM UNTIL  
FRIDAY (24/12Z). ON FRIDAY THE ECMWF KEEP POSITION OF SURFACE LOW TO THE SOUTH  
AS THE ASSOCIATED UPPER FEATURE IS ON DEEP SIDE WITH THE ASSOCIATED UPPER  
LOW....THE GFS LOOKS LIKE THE GDPS/GEPS MEAN.  
 
DEEP LOW PRESSURE SYSTEM TRACKING ACROSS NORTHERN QUEBEC WITH SURFACE TROUGH  
EXTENDING TO THE NORTHWEST OVER SOUTHERN ARCTIC AS THE SYSTEM IS SPINNING  
OVER THE NORTHERN HUDSON BAY BY 22/00Z...  
PREFERRED GUIDANCE: GEPS MEAN  
SCENARIO CONFIDENCE LEVEL: MEDIUM  
THE GDPS REMAIN ON DEEP SIDE WITH THE UPPER LOW OVER WESTERN LABRADOR  
WHICH KEEP POSITION OF SYSTEM A BIT TO THE EAST OVER THE HUDSON BAY AND  
NORTHERN LABRADOR. ON WEDNESDAY (22/00Z) GEPS MEAN IS ON WEAK SIDE BUT OVER  
CENTRAL HUDSON BAY NOT FAR WITH THE ECMWF JUST TO THE NORTHEAST BUT NOT BY MUCH  
WHILE THE GFS KEEP IT TO THE SOUTH WHILE THE GDPS OVER SOUTHERN ARCTIC/NORTHERN  
HUDSON BAY. ALSO WE CAN SEE THAT GDPS SEEM TO DEVELOP A SYSTEM ALONG THE DAVIS  
STRAIT JUST LIKE THE GFS WHILE GEPS MEAN/ECMWF DO NOT SHOW THAT.  
 
 
THE COMPLETE VERSION OF THIS DISCUSSION IS AVAILABLE AT THE FOLLOWING LINK:  
[HTTP://COLLABORATION.CMC.EC.GC.CA/CMC/CMOP/FXCN/20171118/FX_D4-7_WEST_2017111800.HTML]  
 
END/LAROCQUEY  
 
 
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