525
FXUS10 KWNH 310451
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1150 PM EST THU JAN 30 2020
VALID JAN 31/0000 UTC THRU FEB 03/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION AND PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...EVOLUTION OF TROUGH OVER EASTERN HALF OF THE U.S. THROUGH SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~
PREFERENCE: BLEND OF 12Z ECMWF/UKMET...SUPPORTED BY 12Z GEFS MEAN
AND 00Z ECMWF ENSEMBLE MEAN
CONFIDENCE: AVERAGE
DOWNWIND OF A SHARP WESTERN U.S. RIDGE, NORTHWESTERLY FLOW WITH
SOUTHERN AND NORTHERN STREAM COMPONENTS WILL ABSORB A LOW SHEARING
OUT OF MEXICO, FORMING A FULL-LATITUDE TROUGH OVER THE EASTERN
U.S. THROUGH SATURDAY. THE LATEST RUNS OF THE NAM AND GFS MADE A
SHIFT BACK TOWARDS A MORE SOUTHERLY TRACK WITH ITS SOUTHERN STREAM
ENERGY, RESULTING IN A POSITIVELY TILTED TROUGH AXIS THAT WAS A
BIT FARTHER SOUTH OF WHERE THE 12Z RUNS PLACED IT. THE RESULTING
CYCLOGENESIS ALONG OR NEAR THE SOUTHEAST COAST IS ON PAR WITH
PREVIOUS RUNS NEAR THE RIGHT ENTRANCE REGION OF A 140 TO 160 KT
UPPER JET.
...PACIFIC NORTHWEST ATMOSPHERIC RIVER LEADING A LONGWAVE TROUGH
PUSHING INTO THE WEST ON SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF 12Z ECMWF / UKMET...SUPPORTED BY 12Z GEFS
MEAN AND 00Z ECMWF ENSEMBLE MEAN
CONFIDENCE: AVERAGE
THE LEADING EDGE OF AN ATMOSPHERIC RIVER REACHING THE WASHINGTON
COAST OVERNIGHT WILL WAIVER NORTH/SOUTH THROUGH FRIDAY NIGHT
BEFORE SHIFTING DOWN THE OREGON COAST SATURDAY. THIS OCCURS IN
ADVANCE OF A LONGWAVE TROUGH THAT REACHES TO CENTRAL CALIFORNIA AS
IT PUSHES INLAND SUNDAY. THE 31/00Z SUITE OF DID LITTLE TO SETTLE
THE DILEMMA WITH RESPECT TO WHERE THE EXACT AXIS AND TIMING OF
HEAVY PRECIPITATION SETS UP LATER ON DAY 1 AND INTO ON DAY 2 AS
WELL AS THE TIMING OF THE TROUGH THAT MOVES ASHORE BY DAY 3 ALONG
WITH ANY ASSOCIATED CYCLOGENESIS. WITH THE NCEP GUIDANCE SHOWING
REASONABLY GOOD AGREEMENT WITH THEIR PREVIOUS RUNS, THE 30/12Z
ECMWF IS STILL PROBABLY A BIT TOO SLOW AND THE 31/00Z GFS MAY BE A
TAD TOO FAST. IN PARTICULAR, IT LOOKS LIKE THE GFS IS TOO QUICK
IN PHASING CUTOFF ENERGY OVER THE SOUTHWEST U.S. BACK INTO THE
ZONAL FLOW. THE UKMET OFFERS A NICE MIDDLE GROUND, SO WE RECOMMEND
AN ECMWF/UKMET BLEND, ALTHOUGH THE GFS IS REALLY ONLY MINIMALLY
FASTER.
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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