Srain Posted January 7, 2012 Share Posted January 7, 2012 The HPC Morning Update discusses the variability that is present regarding late next week into the weekend of the Olympic Trails Marathon and the upper low that could be lurking to our W... PRELIMINARY EXTENDED FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 731 AM EST SAT JAN 07 2012 VALID 12Z WED JAN 11 2012 - 12Z SAT JAN 14 2012 MODELS SHOW AN AMPLIFYING CENTRAL TO EASTERN US TROUGH DAYS 3-6 WITH THE TROUGH DEAMPLIFYING ON DAY 7. UPSTREAM...THE PRIMARY UNCERTAINTY REVOLVES AROUND THE EVOLUTION OF A WAVE AND POTENTIAL 500 MB CLOSED LOW MOVING EITHER OFF THE CA COAST OR ONSHORE AND EVENTUALLY INTO THE SOUTHWEST. ON DAY 7...A HIGH AMPLITUDE WAVE OVER THE NORTHEAST PACIFIC MOVES TOWARDS THE PACIFIC NORTHWEST AND BRITISH COLUMBIA. THE GENERAL AGREEMENT ON THE LARGE SCALE PATTERN LED TO A CONSENSUS APPROACH...WITH MORE WEIGHTING TOWARDS THE 00Z ECMWF ENSEMBLE MEAN IN LATER PERIODS. THUS...CONFIDENCE IS NEAR NORMAL THROUGH THE PERIOD...WITH THE EXCEPTION OF BELOW NORMAL CONFIDENCE IN THE SOUTHWEST WITH THE CLOSED LOW EVOLUTION. A MULTI-MODEL/ENSEMBLE MEAN APPROACH WAS USED. EASTERN AND CENTRAL US... THE 00Z ECMWF/GFS/UKMET WERE IN GOOD AGREEMENT ON THE PROGRESSION OF THE CLOSED LOW LEAVING TX ON DAY 3 AND MOVING INTO THE TN VALLEY BY DAY 4 AND ACROSS THE NORTHEAST ON DAY 5. THIS SYSTEM WILL BRING WIDESPREAD PRECIPITATION TO THE EASTERN US. THIS SYSTEM WILL BE FOLLOWED BY A DEEP LAYER TROUGH MOVING EAST FROM THE CENTRAL US. THE 00Z ECMWF CLOSED OFF A 500 MB LOW SOUTH OF THE 12Z FRI RUN ON THU 12 JAN. THE 00Z ECMWF/GEFS MEANS/00-06Z GFS/00Z UKMET SHOW THE DEVELOPING LOW FURTHER NORTH NEAR LK SUPERIOR ON THU. THE MULTI-MODEL/ENSEMBLE MEAN APPROACH MITIGATED THE IMPACT OF THE ONE RUN ADJUSTMENT OF THE OPERATIONAL ECMWF. THE MEAN EASTERN TROUGH STARTS TO DEAMPLIFY AND MOVE EAST ON DAYS 6-7...WITH THE 0Z GFS STANDING OUT FROM THE PACK OF SOLUTIONS BY MOVING THE TROUGH FASTER THAN THE LARGE MAJORITY OF ECMWF/GEFS ENSEMBLE MEMBERS/RESULTANT MEANS AND 12Z FRI-00Z SAT OPERATIONAL ECMWF. WESTERN US... THE DRY PATTERN OF LATE IN THE PACIFIC NORTHWEST CONTINUES AS THE DEPARTURE OF THE NORTHERN ROCKIES TROUGH ON DAY 3 IS FOLLOWED BY THE APPROACH OF A DEEP LAYER RIDGE FROM THE NORTHEAST PACIFIC. THIS RIDGE PERSISTS UNTIL DAY 7...WHEN THE NEXT NORTHEAST PACIFIC TROUGH DEVELOPS AND DRIFTS TOWARDS THE COAST. THIS TROUGH IS ANTICIPATED BY TELECONNECTIONS FROM THE PERSISTING UPPER RIDGE SOUTH TO SOUTHWEST OF THE ALEUTIANS...AND SHOWN IN THE MAJORITY OF MODELS/RUNS. THE 06Z GFS WAS AN OUTLIER WITH FASTER PROGRESSION OF THE TROUGH...WITH BETTER CLUSTERING AMONG THE 12Z FRI-00Z SAT ECMWF/ECMWF ENSEMBLE MEAN/00Z GFS. SOUTH OF THE MEAN RIDGE POSITION...THE MODELS FORECAST A WAVE TO MOVE SOUTH ACROSS CA AND ADJACENT COASTAL WATERS...AND POSSIBLY INTO THE SOUTHWEST WITH TIME. THE MODELS AND ENSEMBLES SHOW WEST-EAST VARIABILITY OF WHERE A CLOSED LOW DEVELOPS. THE 00Z ECMWF DEVELOPMENT IS OFF THE COAST AND THE 00Z-06Z GFS/00Z UKMET CLOSED LOW DEVELOPS ONSHORE. THE 06Z GFS MARKS THE EASTERN EDGE OF THE CLUSTER OF SOLUTIONS WITH THE CLOSED LOW POSITION/TRACK NEXT THU 12 JAN TO SAT 14 JAN. A MULTI-MODEL/ECMWF ENSEMBLE MEAN APPROACH RESULTS IN SHOWING THE ELONGATED TROUGH ACROSS THE REGION BUT NOT COMMITTING TO ANY ONE SOLUTION...GIVEN THE LARGE SPREAD AND ABOVE NORMAL UNCERTAINTY AS TO WHERE THE CLOSED LOW WILL DEVELOP WITHIN THE 500 MB TROUGH AXIS. Link to comment Share on other sites More sharing options...
Srain Posted January 7, 2012 Author Share Posted January 7, 2012 The good news for those attending the Olympic Trails Marathon is the 12Z GFS is suggesting the front will pass on Thursday. The interesting features are a short wave trough to our W and a developing Coastal Low/trough along the Lower/Middle Texas Coast spreading over running precip as that low begins to strengthen... Link to comment Share on other sites More sharing options...
Srain Posted January 7, 2012 Author Share Posted January 7, 2012 The GFS Ensembles and Canadian paint a rather interesting scenario for later next week into Saturday... Link to comment Share on other sites More sharing options...
Srain Posted January 10, 2012 Author Share Posted January 10, 2012 It is looking like a great forecast for the Olympic Trails Marathon on Saturday. Dry and cool conditions appear to be ahead. A strong Canadian front will pass Wednesday night/Thursday morning and should be well offshore mid day Thursday. The weak upper low well off California can be seen on water vapor imagery and should stay out of our hair allowing for near perfect conditions for the Marathon... Link to comment Share on other sites More sharing options...
Srain Posted January 10, 2012 Author Share Posted January 10, 2012 Light freeze area wide Friday morning and possibly Saturday morning as the strong Canadian front passes very early on Thursday morning. Gusty winds during the day Thursday should make it difficult to reach the mid 50's. If we have some clouds, upper 40's like we saw today may not be out of the question. Cold and dry for the Olympic Trails Marathon on Saturday with some possible mid/high clouds as a weak upper air disturbance passes in an upper NW flow looks possible. Good luck to all those in the Houston Marathon as well on Sunday! Link to comment Share on other sites More sharing options...
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