413
FXUS10 KWNH 290653
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
153 AM EST WED JAN 29 2020
VALID JAN 29/0000 UTC THRU FEB 01/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SPLIT FLOW TROUGH CROSSING THE GREAT PLAINS TODAY AND REACHING
THE SOUTHEAST WEDNESDAY NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
THE LATEST NUMERICAL GUIDANCE REMAINS IN DECENT AGREEMENT WITH THE
EVOLUTION OF A SHORTWAVE WHICH WAS OVER THE SOUTHERN PLAINS AT
29/00Z. AS THE WAVE TRACKS EAST, THE 29/00Z NAM WAS SLIGHTLY
FASTER THAN THE 28/12Z RUNS AND WELL WITHIN THE CLUSTERING OF
OTHER MODEL GUIDANCE. A GENERAL MODEL BLEND SHOULD LOOK VERY
SIMILAR TO ANY OF THE INDIVIDUAL MODEL RUNS WHILE DAMPENING THE
MINOR DIFFERENCES IN AMPLITUDE AND SPEED OF PROPAGATION.
...SPLIT FLOW TROUGH IN NORTHERN STREAM FROM THE UPPER MIDWEST TO
THE MID-ATLANTIC THURSDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 28/12Z UKMET BLEND
CONFIDENCE: AVERAGE
THE NUMERICAL GUIDANCE GOT INTO BETTER AGREEMENT WITH RESPECT TO
THE ENERGY IN THE NORTHERN STREAM DURING THE 28/12Z MODEL RUNS.
THERE WERE A COUPLE OF MINOR RUN TO RUN DIFFERENCES IN THE NAM AND
GFS...BUT THE OVERALL SOLUTION CHANGED LITTLE. THAT LEAVES THE
28/12Z UKMET BEING A MORE AMPLIFIED SOLUTION WITH THE WAVE THAT
MAKES ITS WAY ACROSS PARTS OF THE GREAT LAKES AND OHIO VALLEY. NO
REASON TO CHANGE PREFERENCES BASED ON THE 29/00Z GUIDANCE.
...MID-LEVEL TROUGH OVER THE PACIFIC NORTHWEST TODAY AND
AMPLIFYING INTO THE DESERT SOUTHWEST WEDNESDAY, REACHING THE
SOUTHERN PLAINS THURSDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 29/00Z GFS AND 28/12Z ECMWF BLEND
CONFIDENCE: AVERAGE
BOTH THE 29/00Z GFS AND 28/12Z OPERATIONAL ECMWF SHOWED SHORTWAVE
ENERGY DROPPING SOUTH AND FORMING A CLOSED LOW WHICH DROPS INTO
NORTHERN MEXICO...AN IDEA THAT WAS SUPPORTED BY THE ECMWF
ENSEMBLES...WHILE THE NAM AND UKMET WERE BOTH HEDGING TOWARDS A
FASTER SOLUTION WITHOUT THE DEPTH OF THE ECMWF/GFS. WILL NOT MAKE
ANY CHANGES TO THE EARLIER PREFERENCE FOR THE GFS/ECMWF BLEND.
...MID-LEVEL TROUGH ENTERING BRITISH COLUMBIA ON WEDNESDAY AND
AMPLIFYING SOUTHWARD INTO THE GREAT PLAINS BY FRIDAY MORNING...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 28/12Z ECMWF AND 28/12Z CMC HYBRID
CONFIDENCE: BELOW AVERAGE
UNCERTAINTY REMAINED HIGH AS THE MODELS STRUGGLE WITH THE SOUTHERN
END OF A SHORTWAVE TROUGH AND HOW IT EVOLVES ONCE IT CROSSES
THROUGH A RIDGE CENTERED OVER SOUTHWESTERN CANADA AND THE
NORTHWESTERN U.S.. NEITHER THE NAM OR GFS HAD VERY GOOD RUN TO
RUN CONSISTENCY. THE GFS AND CANADIAN HAVE BOTH BEEN INDICATING A
COMPACT CLOSED LOW SHOULD FORM SOMEWHERE OVER THE UPPER MIDWEST OR
CENTRAL PLAINS THAT THEN HEADS EASTWARD INTO THE OHIO VALLEY LATER
IN THE DAY. THE 29/00Z NAM WAS NOT INCLUDED IN THE MODEL
PREFERENCES GIVEN ITS LACK OF SUPPORT FROM ANY OF THE OTHER
OPERATIONAL OR ENSEMBLE RUNS. THE QUESTION THEN REVOLVES AROUND
THE PREFERENCE OF THE DEEP, BROAD OPEN TROUGH LIKE THE ECMWF OR
THE SOLUTIONS INCLUDING A LOW. THINKING IS THAT THE OVERALL
ANSWER MAY INVOLVE A WEAK AND MORE POORLY DEFINED LOW CLOSER TO
THE H5 LOW SHOWN BY THE 28/12Z CMC WITHIN A BROADER FLOW PATTERN
CLOSER TO THE ECMWF IDEA. CONFIDENCE IS BELOW AVERAGE.
...LEADING EDGE OF LONGWAVE TROUGH, OFFSHORE OF THE WEST COAST OF
CANADA FRIDAY EVENING AND DOWNSTREAM ATMOSPHERIC RIVER INTO THE
PACIFIC NORTHWEST...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE
AFTER THE PASSAGE OF A SHORTWAVE AND ACCOMPANYING COLD FRONT INTO
BRITISH COLUMBIA ON THE 30TH, INITIALLY ZONAL FLOW INTO WESTERN
CANADA WILL BEGIN TO AMPLIFY AS RIDGING INCREASES AHEAD OF AN
UPSTREAM SHORTWAVE NEAR 40N 145W BY 01/00Z. ENSEMBLE MEANS AND THE
REMAINING DETERMINISTIC CONSENSUS SUGGEST THAT THE 29/00Z GFS AND
29/12Z CMC MAY BE A BIT TOO QUICK WITH THE SHORTWAVE...SO A BLEND
OF THE 29/00Z NAM AND 28/12Z ECMWF/UKMET REMAINS CLOSEST TO THE
RELATIVELY AGREEABLE ENSEMBLE MEAN'S POSITION AND THE DOWNSTREAM
ATMOSPHERIC RIVER MOVING INTO THE PACIFIC NORTHWEST.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
BANN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page