975
FXUS10 KWNH 180530
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
129 AM EDT WED MAR 18 2020
VALID MAR 18/0000 UTC THRU MAR 21/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..DEEP UPPER TROUGH/CLOSED LOW IMPACTING THE WEST
..LOW PRESSURE TRAVERSING THE HIGH PLAINS/MIDWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS, 12Z CMC AND 12Z ECMWF
CONFIDENCE: AVERAGE
A DEEP AND ELONGATED UPPER TROUGH WITH MULTIPLE CLOSED LOW CENTERS
WILL PIVOT WELL INLAND ACROSS THE INTERMOUNTAIN WEST BY WEDNESDAY
WHICH AND SET THE STAGE FOR LEE-SIDE CYCLOGENESIS OVER THE CENTRAL
HIGH PLAINS. IN PARTICULAR, THE CLOSED LOW CENTER CURRENTLY
SITUATED NEAR THE BASE OF THE TROUGH WEST OF THE BAJA PENINSULA
WILL QUICKLY EJECT NORTHEAST ACROSS THE SOUTHWEST ON WEDNESDAY AND
ARRIVE OVER THE CENTRAL HIGH PLAINS BY EARLY THURSDAY AND BE THE
DOMINANT PLAYER IN DEEPENING SURFACE LOW PRESSURE ACROSS THIS
REGION WHICH SHOULD LIFT NORTHEAST TOWARD THE UPPER GREAT LAKES BY
EARLY FRIDAY. THE 00Z NAM IS AGAIN SOMEWHAT STRONGER AND FASTER
THAN THE GLOBAL MODEL GUIDANCE WITH THIS SYSTEM, AND SUGGESTS A
LOW TRACK A TAD NORTHWEST OF THE GLOBAL MODEL GUIDANCE RELATING TO
ITS TRACK ACROSS THE MIDWEST AND UPPER GREAT LAKES. THE 12Z UKMET
OVERALL DOES STILL APPEAR TO BE TOO SLOW WITH ITS HEIGHT FALL
PROGRESSION AND ALSO ENDS UP WITH A NOTABLY FLATTER/WEAKER SURFACE
WAVE EVOLUTION. WHILE STILL AWAITING ARRIVAL OF THE 00Z NON-NCEP
MODELS, THE BETTER CLUSTERING TENDS TO BE TOWARD THE 00Z GFS, 12Z
CMC AND 12Z ECMWF FOR MOST OF THE PERIOD, AND SO A BLEND OF THESE
SOLUTIONS WILL BE PREFERRED FOR NOW.
..CLOSED LOW/ENERGY LINGERING OVER THE GREAT BASIN FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: ABOVE AVERAGE
THE LATEST GOES-17 AIRMASS RGB AND AMV DATA SHOW A WELL-DEFINED
AND SOMEWHAT ELONGATED CLOSED LOW OVER WESTERN NV WHICH IS
EMBEDDED IN THE AFOREMENTIONED DEEP WESTERN U.S. TROUGH AXIS. THIS
PARTICULAR LOW CENTER DOES NOT EJECT EAST OVER THE NEXT FEW DAYS
AND INSTEAD GETS LEFT BEHIND OVER THE GREAT BASIN. THE 00Z NAM
TENDS TO PLACE THE SYSTEM A TAD EAST OF THE GLOBAL MODELS. ALL OF
THE MODELS WEAKEN THE SYSTEM BY FRIDAY, AND SUGGEST THE ENERGY
WILL ELONGATE MORE EAST/WEST AND SHEAR OUT ON SATURDAY. A NON-NAM
BLEND WILL BE PREFERRED WITH THIS ENERGY.
..SERIES OF TROUGHS ARRIVING OVER THE NORTHERN HIGH PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS, 12Z UKMET AND 12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODELS BRING A SERIES OF NORTHERN STREAM SHORTWAVE TROUGHS
DOWN TOWARD THE NORTHERN HIGH PLAINS, WITH ONE ARRIVING BY LATE
WEDNESDAY, AND THEN AN ADDITIONAL ONE ON FRIDAY. THE 00Z NAM
OVERALL IS A TAD SLOWER AND DEEPER THAN THE GLOBAL MODELS WITH THE
INITIAL SYSTEM, AND THEN THIS MODEL ALONG WITH THE 12Z CMC TEND TO
BE A LITTLE SLOWER AND DEEPER WITH THE SECOND ONE. WILL PREFER THE
CLUSTERING OF THE 00Z GFS, 12Z UKMET AND 12Z ECMWF WITH THESE
SHORTWAVES AS THEY ARRIVE ACROSS THE NORTHERN PLAINS AND ADVANCE
EAST TOWARD THE UPPER MIDWEST AND GREAT LAKES REGION.
..TROUGH ARRIVING OVER SOUTHERN CA BY SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: BELOW AVERAGE
A NEW SURGE OF HEIGHT FALLS WILL BE DROPPING DOWN OFF THE WEST
COAST BY THE END OF THE WEEK AS A DEEP CLOSED LOW CENTER EVOLVES
SOUTH FROM THE GULF OF AK. AHEAD OF THIS CLOSED LOW WILL BE A
SEPARATE AND SMALLER CLOSED LOW CENTER THAT GETS CAUGHT UP IN THE
THE LARGER SCALE CYCLONIC FLOW OFF THE WEST COAST AND GETS
SLINGSHOTTED EAST TOWARD SOUTHERN CA AS A PROGRESSIVE SHORTWAVE
TROUGH. THE 12Z UKMET IS THE SLOWEST AND DEEPEST SOLUTION WITH
THIS SYSTEM. THE 12Z ECMWF IS ALSO ON THE SLOWER SIDE OF THE
GUIDANCE, BUT HAS SOME ENSEMBLE SUPPORT FROM THE ECENS MEAN. THE
REMAINING GUIDANCE LED BY THE 00Z GFS AND 00Z NAM ARE A BIT MORE
PROGRESSIVE AND HAS MORE SUPPORT FROM THE GEFS MEAN. WILL SUGGEST
A NON-UKMET BLEND AT THIS POINT, BUT WITH LIMITED CONFIDENCE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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