611
FXUS10 KWNH 161609
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1108 AM EST SUN FEB 16 2020
VALID FEB 16/1200 UTC THRU FEB 20/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES & CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..GREAT LAKES/GULF THROUGH EAST COAST SYSTEM(S)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 06Z GFS AND 00Z ECMWF/CMC BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
BROAD GLOBAL CYCLONIC FLOW CURRENTLY EXIST ACROSS THE CONUS WITH A
HIGHLY SHEARED SHORTWAVE MOVING THROUGH OLD MEXICO INTO THE GULF
REGION SPARKING SOME DISTURBED WEATHER ACROSS THE GULF COAST THAT
WILL SHIFT INTO THE SOUTHEAST BY MONDAY. GUIDANCE IS FAIRLY SOLID
IN THE REMAINING EVOLUTION OF THIS PATTERN IN ADVANCE OF STILL
BROAD BUT SHARPENING OF A TROF ACROSS THE NORTH CENTRAL PLAINS
INTO THE SNAKE RIVER PLAIN BY MONDAY MORNING. THE LEADING EDGE OF
THE HEIGHT-FALLS IN COMBINATION WITH A DIGGING ARCTIC SHORTWAVE
WILL AMPLIFY THROUGH THE GREAT LAKES MONDAY INTO TUESDAY. THERE
REMAINS MODEST MODEL SPREAD MAINLY IN THE SPACING AND TIMING OF
THESE WAVES BETWEEN EACH OTHER. THE 00Z UKMET TRENDED MUCH WEAKER
WITH THE LEAD PACIFIC ENERGY, WHILE THE NAM APPEARS TO GO TO THE
OPPOSITE EXTREME THOUGH THE RESULTANT SURFACE WAVE IS CONGRUENT
WITH THE REMAINING GUIDANCE/ENSEMBLE SUITE IT IS A BIT TOO STRONG
WITH THE SURFACE WAVE AND MOISTURE FLUX INTO THE SYSTEM TO BE
ACCEPTABLE IN A BLEND AT THIS TIME (THIS ALSO REDUCES
CONVERGENCE/QPF ACROSS THE SOUTH AS A RESULT). THE 12Z GFS
TRENDED A BIT FASTER WITH THE SHORTWAVE EMERGING OUT OF THE
NORTHERN ROCKIES, WHICH TRACKS THE SURFACE WAVE A BIT TOO FAST
THROUGH THE GREAT LAKES INTO THE NORTH-EAST. THE 06Z RUN IS MORE
IN LINE WITH THE FLATTER CMC AND SLIGHTLY SLOWER ECMWF WHICH
APPEAR TO BE THE NORMAL BIASES, ONCE BLENDED FIT NICELY TOWARD
VERIFICATION...SO WILL SUPPORT A 06Z GFS/ECMWF/CMC BLEND WITH THIS
SYSTEM CROSSING THE GREAT LAKES THROUGH THE SOUTH AND EAST COAST
FROM LATE MONDAY THROUGH THE END OF THE FORECAST PERIOD.
...DEVELOPING POSITIVE TILT WESTERN TROF WITH WINTER PRECIP IN
SOUTHERN HIGH PLAINS WED...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS AND 00Z CMC/UKMET BLEND
CONFIDENCE: AVERAGE
FURTHER WEST, AS THE TAIL END OF THE INITIAL SHORTWAVE SWINGS OUT
OF THE ROCKIES INTO THE GREAT LAKES ON TUESDAY; REINFORCING
SHORTWAVE ENERGY OVER-TOPS THE AMPLIFYING PACIFIC RIDGE DROPPING
INTO THE DEVELOPING LARGER SCALE TROF OVER THE WEST BY WED. THIS
WAVE, IN COMBINATION WITH EMERGING SHORTWAVE ENERGY OUT OF THE
EAST-CENTRAL PACIFIC (UNDER THE PACIFIC RIDGE, AS WELL AS
LINGERING FRONTAL ZONE ACROSS TX INTO THE SOUTHERN HIGH PLAINS
WILL SET UP THE NEXT SYSTEM WITH THE POTENTIAL FOR WINTRY PROBLEMS
BY LATE WED INTO THURSDAY. HERE, THERE IS MUCH MORE SUBSTANTIAL
SPREAD, KEYING ON THE TIMING OF THE THE CENTRAL PACIFIC
SHORTWAVE/MOISTURE TRANSPORT THROUGH THE DESERT SOUTHWEST INTO THE
AREA OF CONCERN. HERE THE ECMWF SHOWS THE GREATEST TIMING
DIFFERENCES BEING QUITE SLOW WITH THE WAVE, MAINLY AS IT LOST SOME
ENERGY TO THE NORTHERN STREAM ALONG THE WESTERN SIDE OF THE
DEVELOPING PACIFIC RIDGE, WHICH DELAYS THE ENERGY ADVANCING AS
WELL AS DROPPING THE FOCUS FURTHER SOUTH. SO AS THE SHORTWAVE
FROM THE NORTHERN STREAM DROPS, IT DOES NOT PHASE/AMPLIFY DELAYING
ITS EJECTION INTO THE PLAINS. THE 12Z GFS AND 00Z CMC ARE MUCH
FASTER WITH THIS SHORTWAVE CAPTURE AND START TO BREAK OUT
INCREASED QPF ACROSS THE SOUTHERN HIGH PLAINS/TX BY 00Z THURSDAY.
EVEN THOUGH IT IS TYPICAL OF THE GFS TO HAVE A FAST BIAS, THE
SIMILARITY IN TIMING PRESENTED BY THE 00Z CMC AND UKMET SUGGEST
LESS OR NO INFLUENCE OF THE ECMWF IN A PREFERRED BLEND AT THIS
TIME. WHILE NOT FAVORED DUE TO TYPICAL DEEPER/OVER-AMPLIFIED
SOLUTION THROUGH THE WEST; THE 12Z NAM IS ALSO FASTER LIKE THE
GFS/CMC WITH THIS ENERGY, PROVIDING SOME CONFIDENCE, AS A STRONGER
MORE AMPLIFIED SYSTEM SHOULD BE SLOWER. CONFIDENCE IN AVERAGE IN
A 12Z GFS AND 00Z CMC/UKMET BLEND FOR THIS FEATURE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
GALLINA
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