FXCN01 CWAO 250930
MAIN WX DISCUSSION
UPPER LEVEL PATTERN
MODELS QUITE AGREE IN THE EVOLUTION OF THE UPPER-LEVEL PATTERN IN THE NEXT
48-HRS, EXCEPT OVER WRN NOAM, WHERE SOME DISCREPANCY ARE NOTED BTN MODELS. WITH
NEXT WAVE APPROCHING BC FROM EPAC BY DAY 2, UKMET FORECAST DEEPER FEATURE WITH
CLOSE UPPER LOW, WHILE ALL OTHER HINT FOR UPPER TROF. GEM-REG MAY ON FAST SIDE,
WHILE NAM AND ECMWF ARE LAGGING BEHIND. GEM-GLB AND GFS ARE IN THE MIDDLE OF THE
PACK ARE GOOD COMPROMISE. MODELS FORECAST MULTIPLE S/W OFF GULF OF ALASKA MOVING
THROUGH NRN PRAIRIES SRN ARCTIC, BUT SOLUTIONS DIFFER FROM MODEL TO ANOTHER ONE.
DIFFERENCES NOTES ALSO WITH UPPER TROF MOVING TOWARDS BFRTS BY T+48, WHILE GFS
IS ON FAST SIDE AND GEM-GLB OFFERS GOOD COMPROMISE. NO PROBLEMS NOTED OVER ERN
CANADA WHERE MODELS FAIRLY AGREE WITH PATTERN.
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WRN RGNS..
EXCEPTED FOR TOO PROGRESSIVE NAM, MODELS AGREE SOMEWHAT WITH AREA OF LOW
PRESSURE SYSTEM BUILDING OVER WRN CANADA FROM SYSTEM ORIGINALLY OVER GULF OF
ALASKA. UKMET AND GEM-GLB ARE ON E SIDE OF CONSENSUS, WHILE GFS AND GEM-REG
OFFER MIDDLE OF THE ROAD SOLUTION AND LOOKS FINE. MODELS HINT FOR DEVELOPMENT
OF NEW LOW BY T+48 OVER NWT AND SEEMS REASONABLE. IN GENERAL MASS FIELD PATTERN
QUITE SIMILAR WITH SAME RANGE OF SLP. QPF-WISE, GEM-REG REMAINS A BIT ON WET
SIDE ALONG BC COAST, WHILE NAM, GFS AND GEM-GLB FORECAST SIMILAR QPF PATTERN
AND AMOUNTS. GEM-REG SEEMS ON SLOW/LOW SIDE WITH PCPN ASSOCIATED TO SFC TROF
OVER PRAIRIES, WHILE THE LATTER TRIO HINT FOR FASTER MOTION WITH HIGH AMOUNTS.
HENCE GEM-GLB IS RECOMMENDED HERE. CMC SIG WX CHARTS SHOW 30-50 MM+ OF RAIN
OVER BC SHORE AND 15 CM+ OVER HIGHER TERRAIN AND ROCKIES. CHASRTS SHOW 10 CM OF
SNOW OVER NRN SK ASSOCIATED TO TROF. STRONG WINDS WILL PERSIST OVER CNTRL BC
COAST.
ALSO, NOTING THAT GEM-REG AND GEM-GLB ARE ALONE IN FORECAST FASTER INLAND
IMPUSLE FROM EPAC AFFECTING SRN BC/WA, WHILE CONSENSUS HINT SYSTEM OVER WRN USA
SEABORD. GEMS MODELS FORECAST STRONG UPPER RIDGE BEHIND WHILE FOREING HINT FOR
WEAKER FEATURE. ECMWF IS BTN CONSENSUS AND GEMS MODELS MAY REPRESENT BEST
GUESS GIVEN THAT THERE IS TOO MUCH DIFFERENCES BTN BOTH GROUPS. CEPS ARE
ON GEMS SIDE HERE WITH STRONG SFC RIDGE WITH LOW FURTHER INLAND. HOWEVER PCPN BY
GEM-REG LOOKS SUSPICIOUS BY T+48 OVER SRN BC/NRN WA. CONFIDENCE IS ON LOW SIDE.
HIGH ARTIC..
MODELS QUITE AGREE WITH LOW MOVING NWD AFFECTING XTRM NRN ARCTIC WITH SIG SN
PCPN. GEM-REG WELL SUPPORTS BY FOREING MODELS GIVES RELIABLE GUIDANCE. 5=10 CM
ON THE MENU OVER ELISLD. ALSO POTENTIAL OF NR BLIZZARD CONDITIONS IN THIGHT
GRADIENT AREA OVER CNTRL ARCTIC.
GRTLKS LOW WITH NWD EXTNTION TROF..
GOOD AGREEMENT BTN MODELS WITH DOUBLE BARREL LOW AFFECTING ON/QC WHERE MODELS
LOCATES NRN LOW IN SIMILAR PLACE, EXCEPT FOR UKMET TRACKING FURTHER E, AND NAM
3-6 HPA DEEPER THAN CONSENSUS. MODELS ALSO PUT SOME ENERGY ON SR LOW NR GGBAY,
WHERE GEM-REG MAY BE 2 HPA DEEPER THAN CONSENSUS, WHITOUT MUCH DIFFERENCES IN
QPF FORECAST. QPF-WISE, GIVEN THAT NAM IS DEEPER OVER NRN SXNS, IT MAY OVERDO
AMOUNTS, IN COMPARISON OF ALL OTHER MODELS CONSULTED AND IS NOT RECOMMENDED.
GEM-REG WELL SUPPORTED BY GEM-GLB AND GFS IS SUGGESTED. HOWEVER, NCEP MODELS
STILL ON COLDER SIDE COMPARING RA/SN LINE... BUT NOT SO MUCH. FZ PCPN POSSIBLE
BT T+30 OVER ERN SAGUENAY AREA THROUGH COTE NORD/SRN LBRDR BORDER BY T+48. CMC
SIG WX CHARTS SHOW 5-10 CM OVER CNTRL QC AND WRN LBRDR.
ATLANTIC CANADA LOW..
GEM-REG KEEPS ITS TREND TO BE MORE PROGRESSIVE AND AGRESSIVE THAN ALL OTHER
MODELS. HENCE IDEA IN EARLY FX IN REJECTING GEM-REG DOESN'T CHANGE HERE.
CONSENSUS SUGGESTS WEAKER AND MORE SWRN TRACK. NAM MAYBE TOO WEAK SUGGEST
FURTHER N TRACK AND IS REJECTED AS WELL. GFS SUPPORTED BY ECMWF AND CEPS ARE
BEST GUESS AT THE MOMENT. QPF-WISE, EXCEPT FOR NAM WITH ITS OWN SOLUTION, GFS,
GEM-REG AND GEM-GLB SHOW SIMILAR PATTERN, EVEN IF THEIR MASS FIELD FORECAST
DIFFER A BIT. BLEND OF GEM-REG AND GFS SEEMS A GOOD COMPROMISE HERE.
BY T+48, ANOTHER IMPULSE FROM USA SEABORD WILL APPROACH ATLANTIC CANADA. AT THE
MOMENT MODELS HINT THAT BULK OF PCPN WILL STAY WAY OFF SRN NS WATERS, BUT COULD
AFFECT MARITIMES BEYOND THAT. GEM-REG AND ESPECIALLY GEM-GLB MAYBE TOO
PROGRESSIVE.... LATENT HEAT RELEASE MAY BE IN CAUSE AGAIN HERE.
END/CHENARD