370
FXUS10 KWNH 291651
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1151 AM EST WED JAN 29 2020
VALID JAN 29/1200 UTC THRU FEB 02/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL SYNOPSIS
AN ACTIVE PATTERN OVER SOUTHEAST AND PACIFIC NORTHWEST THROUGH
SATURDAY.
...PRIMARY MID-LEVEL TROUGH OVER THE FOUR CORNERS, CROSSING SOUTH
TEXAS THURSDAY AND THE SOUTHEAST FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF 29/00Z ECMWF/UKMET AND 29/12Z GFS
CONFIDENCE: AVERAGE
THIS LEADING SHORTWAVE TROUGH OFF A RIDGE OVER THE INTERIOR
PACIFIC NORTHWEST SWINGS ACROSS NORTHERN MEXICO TONIGHT AND
THURSDAY BEFORE SOUTH TEXAS THURSDAY NIGHT. A SECONDARY TROUGH
DIGS IN BEHIND THURSDAY NIGHT, WEAKENING THE MID-LEVEL ENERGY AS
IT CROSSES THE SOUTHEAST FRIDAY. THE 12Z GFS REMAINS FARTHER NORTH
WITH DAY 2QPF ALONG THE WESTERN/CENTRAL GULF COAST COMPARED TO THE
00Z ECMWF/UKMET. THE 12Z NAM CONTINUES TO DIVERGE FROM CONSENSUS
THURSDAY NIGHT WITH THE INTERACTION OF THE PRIMARY AND SECONDARY
SHORTWAVE TROUGHS OVER THE SOUTHERN PLAINS AND THE 00Z CMC IS
STILL SLOWER THAN THE CONSENSUS WITH THE TROUGH CROSSING SOUTH
TEXAS, SO NEITHER SOLUTION IS PREFERRED.
...SOUTHERN PART OF SECONDARY MID-LEVEL TROUGH DIGGING DOWN THE
ROCKIES FROM CANADA TO MEXICO TONIGHT THROUGH THURSDAY NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF 29/00Z ECENS/ECMWF/UKMET AND SOME 29/12Z GFS
CONFIDENCE: AVERAGE
THE SOUTHERN END OF THIS SHORTWAVE TROUGH CROSSING THE INTERIOR
PACIFIC NORTHWEST RIDGE IS IN BETTER AGREEMENT SO FAR TODAY. THE
00Z ECMWF IS NOW FARTHER WEST THAN THE 12Z GFS AND 00Z UKMET WHICH
FAVOR THE IMMEDIATE LEE SIDE OF THE ROCKIES THROUGH THURSDAY
NIGHT. THIS SOUTHERN END FEATURE THEN SPLITS OFF INTO MEXICO
FRIDAY WITH A TROUGH OVER SOUTHERN TEXAS. THE 12Z NAM FAVORS A
NORTHERN STREAM LOW OVER THE CENTRAL/SOUTHERN PLAINS AND IS AN
OUTLIER WHICH IS SIMILAR TO THE 00Z CMC SOLUTION OF MUCH LESS
FORCING INTO MEXICO.
...NORTHERN PORTION SECONDARY MID-LEVEL TROUGH CROSSING THE
CENTRAL PLAINS THURSDAY NIGHT/FRIDAY AND PUSHING OFF THE SOUTHEAST
COAST SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF 29/00Z ECENS/ECMWF/UKMET AND SOME 29/12Z GFS
CONFIDENCE: BELOW AVERAGE
COMPLEX INTERACTION OF THE NORTHERN STREAM PORTION OF A SECONDARY
SHORTWAVE CROSSING THE INTERIOR PAC NW RIDGE THAT BREAKS OFF LATE
THURSDAY OVER THE NORTHERN PLAINS AND INTERACTS WITH A TROUGH OVER
THE GREAT LAKES FRIDAY INTO SATURDAY. HOWEVER, THERE IS DECENT
AGREEMENT THAT THE RESULTING TROUGH PUSHES OFF THE SOUTHEAST COAST
AND STAYS OFFSHORE AS IT LIFTS NORTH SATURDAY NIGHT/SUNDAY.
EARLIER NOTES ABOUT THE 12Z NAM AND CMC HOLD THAT THEY ARE MUCH
FARTHER SOUTH THAN THE PREFERRED CONSENSUS OF THE EC/GFS/UKMET.
THERE IS STILL DECENT RUN-TO-RUN VARIABILITY OF THIS FEATURE AND
HOW THE PARTS INTERACT AND THE THERMAL DIFFERENCES SO THIS REMAINS
A WAIT AND SEE FOR A SOLID SOLUTION TO BE BORNE OUT.
...LONGWAVE TROUGH APPROACHING THE WEST COAST OF CANADA FRIDAY
NIGHT/SATURDAY AND DOWNSTREAM ATMOSPHERIC RIVER INTO THE PACIFIC
NORTHWEST LATE THURSDAY INTO SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 29/00Z ECENS/ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE
THE PASSAGE OF A SHORTWAVE AND ACCOMPANYING COLD FRONT INTO
BRITISH COLUMBIA THURSDAY WILL INITIALLY BRING ZONAL FLOW INTO
WESTERN CANADA THAT AMPLIFIES AS RIDGING INCREASES AHEAD OF AN
UPSTREAM SHORTWAVE FRIDAY. ENSEMBLE MEANS AND THE REMAINING
DETERMINISTIC CONSENSUS SUGGEST THAT THE 29/12Z GFS AND 29/00Z CMC
REMAIN TOO QUICK WITH THE SHORTWAVE...SO A BLEND OF THE 29/00Z
ECENS/ECMWF/UKMET REMAINS IS RELATIVE AGREEMENT 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
JACKSON
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