290
FXUS10 KWNH 300656
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
155 AM EST THU JAN 30 2020
VALID JAN 30/0000 UTC THRU FEB 02/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH FINAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...PRIMARY MID-LEVEL TROUGH OVER THE FOUR CORNERS NOW, CROSSING
SOUTH TEXAS THURSDAY AND THE SOUTHEAST FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF 29/12Z ECMWF/UKMET WITH SOME 29/12Z CMC AND
30/00Z GFS
CONFIDENCE: AVERAGE
A LEADING SHORTWAVE TROUGH OFF A RIDGE OVER THE INTERIOR PACIFIC
NORTHWEST EARLY THIS EVENING WILL SWING ACROSS NORTHERN MEXICO
THROUGH THURSDAY THEN SOUTH TEXAS ON THURSDAY NIGHT. A SECONDARY
TROUGH DIGS IN BEHIND THURSDAY NIGHT, WEAKENING THE MID-LEVEL
ENERGY AS IT CROSSES THE SOUTHEAST FRIDAY. THE 30/00Z NAM HAD
DECENT RUN TO RUN CONSISTENCY, BUT THAT LEFT THE NAM ON THE SLOWER
SIDE OF THE ENVELOPE OF SOLUTIONS.
...EVOLUTION OF TROUGH OVER EASTERN HALF OF THE U.S. FRIDAY INTO
SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~
PREFERENCE: BLEND OF 30/00Z ECMWF/GFS/NAM
CONFIDENCE: BELOW AVERAGE
COMPLEX INTERACTION OF SEVERAL STREAMS LEADS TO A BELOW AVERAGE
CONFIDENCE FORECAST FROM THURSDAY NIGHT/FRIDAY MORNING THROUGH
SATURDAY. AT JET-STREAM LEVEL, THE FLOW PATTERN SEEMS STRAIGHT
FORWARD ENOUGH WITH THE NOSE OF A 110 TO 130 KT UPPER LEVEL JET
TOPPING THE WESTERN U.S. RIDGE AND NOSING INTO THE UPPER MIDWEST
AND WESTERN GREAT LAKES REGION...WITH THE AXIS OF 130 TO 150 KT
UPPER LEVEL JET ORIENTED FROM SOUTHWEST TO NORTHEAST FROM THE GULF
OF MEXICO INTO THE MID ATLANTIC REGION AND APPROACHING SOUTHERN
NEW ENGLAND.
PART OF THE JET ENERGY DROPS SOUTHWARD ACROSS THE MIDDLE OF THE
COUNTRY, WITH THE 30/00Z NCEP GUIDANCE FORMING A TROUGH WHICH
DROPS SOUTH INTO THE CENTRAL/SOUTHERN PLAINS IN THE WAKE OF THE
SYSTEM MENTIONED ABOVE...WHILE THE NON-NCEP GUIDANCE WAS MORE
INCLINED TO HAVE A MORE UNIFIED FLOW WITH LITTLE MID-LEVEL
DEVELOPMENT WITHIN THE FLOW. FOCUS IS GREATEST HERE CONSIDERING
ITS IMPACTS ON THE DEVELOPMENT OF A SURFACE LOW ALONG THE
SOUTHEAST COAST THAT WOULD CLIP PARTS OF THE MID-ATLANTIC AND
NORTHEAST U.S ON DAYS 2/3. WITH THE 30/00Z ECMWF MOVING TOWARDS
THE IDEA OF A SPLIT BETWEEN NORTHERN AND SOUTHERN STREAM...SUSPECT
THERE WAS A SLOW CONVERGENCE ON A COMMON SOLUTION. HOWEVER, THERE
WAS STILL DISAGREEMENT ON HOW DEEP/STRONG THE SOUTHERN STREAM WILL
BE...WITH THE NCEP GUIDANCE SOME 60 METERS TO 80 METERS DEEPER
THAN THE ECMWF. FOR NOW, THINK STARTING WITH THE NCEP GUIDANCE
AND TEMPERING THE DEPTH OF THE SYSTEM WITH THE ECMWF SHOULD BE A
REASONABLE FIRST GUESS. THE UKMET STARTED TO SHOW A SPLIT FLOW
BUT NOT NEARLY TO THE EXTENT WHILE THE CANADIAN HELD ITS GROUND ON
A MORE UNIFIED FLOW.
FARTHER TO THE NORTH, THERE REMAINS SOME DISAGREEMENT IN TERMS OF
HOW QUICKLY THE NORTHERN STREAM WAVE WILL PROPAGATE EASTWARD
TOWARDS THE NORTHEAST U.S...BUT A BLEND OF THE ECMWF/GFS SHOULD
PROVIDE A DECENT FIRST GUESS THAT MINIMIZES THE DIFFERENCES.
...LONGWAVE TROUGH APPROACHING THE WEST COAST OF CANADA FRIDAY
NIGHT/SATURDAY AND DOWNSTREAM ATMOSPHERIC RIVER INTO THE PACIFIC
NORTHWEST LATE THURSDAY INTO SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 30/00Z ECMWF/UKMET/ECENS/NAM
CONFIDENCE: AVERAGE
THE PASSAGE OF A SHORTWAVE AND ACCOMPANYING COLD FRONT INTO
BRITISH COLUMBIA ON THURSDAY WILL BRING INITIALLY ZONAL FLOW INTO
WESTERN CANADA THAT AMPLIFIES AS RIDGING INCREASES AHEAD OF AN
UPSTREAM SHORTWAVE FRIDAY. GIVEN REASONABLY GOOD RUN-TO-RUN
CONSISTENCY IN THE 30/00Z NCEP GUIDANCE, DETERMINISTIC CONSENSUS
AND ENSEMBLES CONTINUE TO FAVOR A 30/00Z ECMWF/UKMET/NAM FOR THE
TROUGH 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
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