071
FXUS10 KWNH 091717
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1217 PM EST SUN FEB 09 2020
VALID FEB 09/1200 UTC THRU FEB 13/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z NAM/GFS EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...DIGGING TROUGH OVER THE GREAT BASIN/SOUTHWEST TODAY AND
EJECTING EAST TOWARD THE SOUTHERN PLAINS BY TUESDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GFS/00Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE ENSEMBLE GUIDANCE HAS BEEN FAIRLY CONSISTENT OVER THEIR PAST 3
12/00Z CYCLES, WITH PERHAPS A SUBTLE NUDGE TO BE FASTER WITH THE
CLOSED LOW PROGRESSING ACROSS THE SOUTHWEST. THE PREFERENCE IS TO
BE SOMEWHERE CLOSE TO THE LATEST GEFS/ECMWF MEANS WHICH ARE BEST
REPRESENTED BY A 12Z GFS/00Z ECMWF BLEND.
WHILE THE GFS HAS TRENDED SLOWER FROM ITS PREVIOUSLY FASTER
SOLUTIONS, THE 12Z NAM HAS DONE THE OPPOSITE AND TRENDED FASTER
FROM ITS PREVIOUSLY SLOWER SOLUTIONS AND AWAY FROM THE BETTER
MODEL CLUSTERING. THE 00Z UKMET/CMC APPEAR TO BE SLOW ENOUGH,
RELATIVE TO THE LATEST ENSEMBLE MEANS, TO EXCLUDE THEM FROM THE
PREFERENCE.
..NORTHERN STREAM TROUGH CROSSING THE GREAT LAKES TODAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
ONLY MINOR DIFFERENCES REMAIN WITH THIS SYSTEM SUCH THAT A GENERAL
MODEL BLEND CAN BE USED.
..NORTHERN STREAM TROUGH/FRONT OVER THE MIDWEST BY TUESDAY
...ENERGY CROSSING THE GREAT LAKES/NORTHEAST BY WEDNESDAY
MORNING...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THERE ARE ONLY MINOR DIFFERENCES WITH THIS SYSTEM CONCERNING
TIMING AND AMPLITUDE OF THE MID-LEVEL WAVE AND SURFACE REFLECTION.
A GENERAL MODEL BLEND SHOULD BE SUITABLE REGARDING THIS SYSTEM.
..QUASI-STATIONARY FRONT OVER THE GULF COAST STATES BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NEAREST TO THE 00Z ECMWF
CONFIDENCE: AVERAGE
THERE ARE SOME LATITUDINAL DIFFERENCES THAT DEVELOP ON TUESDAY
WITH THE FRONTAL PLACEMENT ACROSS THE GULF COAST STATES. THE 12Z
GFS LOOKS REASONABLE UPSTREAM WITH A CLOSED LOW BUT HAS A WEAKER
RIDGE SITUATED OFF OF THE SOUTHEASTERN U.S. WHICH CAUSES THE FRONT
IN THE GFS TO HAVE THE FRONT FARTHER SOUTH. OVERALL, CONSIDERING
THE RIDGE TO THE SOUTH, THE UPSTREAM CLOSED LOW OVER THE SOUTHWEST
AND A SHORTWAVE/SURFACE LOW TO THE NORTH, THE PREFERENCE IS TO BE
NEAR THE 00Z ECMWF GIVEN IT IS CONSIDERED REASONABLE WITH ALL
SURROUNDING SYNOPTIC SCALE FEATURES.
..SHORTWAVE CROSSING BRITISH COLUMBIA MONDAY NIGHT
..ENERGY DROPPING SOUTHEAST ACROSS THE NORTHERN ROCKIES TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/12Z NAM BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE
UNCERTAINTY HAS DECREASED REGARDING A SHORTWAVE THAT WILL ADVANCE
EAST ACROSS BRITISH COLUMBIA MONDAY NIGHT AND TOWARD THE NORTHERN
ROCKIES ON TUESDAY. MODELS HAVE CONVERGED COMPARED TO YESTERDAY
BUT THE 12Z GFS HAS A NOTABLE SLOWER TIMING OF THE SHORTWAVE
COMPARED TO THE REMAINING DETERMINISTIC GUIDANCE. GIVEN THE
ENSEMBLE MEANS DO NOT SUPPORT THE 12Z GFS AND MATCH BETTER TO A
BLEND OF THE 00Z ECMWF AND 12Z NAM, A NAM/ECMWF BLEND IS
RECOMMENDED. LARGE DIFFERENCES REMAIN IN THE ENSEMBLE GUIDANCE
REGARDING A DOWNSTREAM SURFACE LOW ON WEDNESDAY IN THE UPPER
MIDWEST, BUT A 12Z NAM/00Z ECMWF BLEND IS NEAREST TO BE BEST
CLUSTERING OBSERVED IN THE ENSEMBLE GUIDANCE AT THIS TIME.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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