675
FXUS10 KWNH 120635
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
135 AM EST SUN JAN 12 2020
VALID JAN 12/0000 UTC THRU JAN 15/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH FINAL PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..LARGE SCALE PATTERN/VERY COLD CLOSED LOW IN S CANADA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
07Z UPDATE: SMALL ADJUSTMENTS BY THE 00Z ECMWF/UKMET STAY CLOSE TO
THE ECENS MEAN, BUT WITH OVERALL TIGHTER AGREEMENT TO THE 00Z NAM.
THE CMC AND 00Z GEFS SHOWS SOME INCREASING ELONGATION EASTWARD
BUT ALSO SIMILAR TO THE 00Z NAM, ENOUGH TO CONTINUE INITIAL
PREFERENCE OF A NON-GFS BLEND.
---PRIOR DISCUSSION---
WITH THE SHEARING/STRETCHING OF THE LEAD SHORTWAVE CURRENTLY OVER
OHIO VALLEY LIFTING INTO CONFLUENT FLOW IN THE NORTHEAST BY EARLY
MORNING TODAY, A VERY BROAD LARGE SCALE TROF DEVELOPS ACROSS THE
ENTIRE CONTINENT AS A SMALLER LOBE OF THE LARGER POLAR VORTEX
SETTLES INTO WESTERN CANADA BY SUNDAY. STRONG BUT A LOW WAVY
AMPLITUDE FLOW ALONG THE PERIPHERY OF THIS CENTER WILL ALLOW FOR
NUMEROUS SHORTWAVES TO PROGRESS QUICKLY ACROSS THE CONUS (PLEASE
SEE SECTIONS BELOW). AS FOR THE CENTRAL HUB AND ASSOCIATED ARCTIC
AIR MASS, THE GFS HAS BEEN TOO FAR EAST THROUGHOUT THE LAST WEEK'S
CYCLES AND WHILE THE ECMWF/CMC BOTH HAVE ANCHORED THE WESTERN
SOLUTIONS, THERE IS GREATER CONSISTENCY THERE AS WELL AS, GIVEN
THE OVERALL PATTERN WITH THE ACTIVE WNW FLOW ACROSS THE BERING SEA
INTO THE GULF OF ALASKA AND THE OTHER 'HALF' OF THE VORTEX LOCKED
ON BAFFIN ISLAND. THE 18Z GEFS IS MUCH FURTHER WEST THAN THE
OPERATIONAL 00Z GFS AND WHILE NOT AS FAR WEST AS THE ECWMF/CMC AND
ECENS ENSEMBLE SOLUTIONS IT IS CLOSER TO THE UKMET AND CMC
PARTICULARLY AT THE END OF THE SHORT-RANGE. THE GOOD NEWS IS
THERE ARE LIMITED INFLUENCES ALONG THE ACTIVE SHORTWAVE AXIS, SO
EVEN THOUGH THE GFS IS NOT PREFERRED WITH THE COLD AIR, IT MAY
VERY WELL BE PREFERRED IN THE SHORTWAVE FEATURES ACROSS THE CONUS.
THE 00Z NAM HAS TRENDED NORTH, BUT STILL HAS BEEN FURTHER SOUTH
THAN THE CONSISTENT PATTERN, HOWEVER, THIS IS THE BEST IT HAS BEEN
RELATIVE TO THE SOLUTIONS FOR THE LAST FEW DAYS, THAT
INCORPORATING IT (ALONG WITH THE GEFS) MAY HELP TO STABILIZE THE
UNCERTAINTY REMAINING IN THE OVERALL PATTERN. SO A NON-GFS
PATTERN IS PREFERRED NORTH OF THE CONUS AND ANY THERMALS THAT
BLEED OVER THE US/CANADIAN BORDER THAT COULD BE BETTER HANDLED
WITH OTHER GUIDANCE SOLUTIONS.
...SHORTWAVE #1 - UPPER OHIO VALLEY INTO NORTHEAST TODAY
(SUNDAY)...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
07Z UPDATE: NO SIGNIFICANT CHANGES WITH THE NEW ECMWF/GEFS/CMC OR
UKMET WERE NOTED TO DIVERGE FROM THE INITIAL GENERAL MODEL BLEND
PREFERENCE.
---PRIOR DISCUSSION---
THIS SYSTEM HAS MATURED AND IS SLIDING INTO INCREASINGLY CONFLUENT
FLOW AS IT TRACKS INTO THE NORTHEAST LATER TODAY AND THROUGH THE
CANADIAN MARITIMES. OVERALL THE SPREAD IS QUITE LOW TO SUPPORT A
GENERAL MODEL BLEND FOR THIS SYSTEM AT ABOVE AVERAGE CONFIDENCE.
..SHORTWAVE #2 - CENTRAL ROCKIES TODAY THUR GREAT LAKES MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
07Z UPDATE: THE 00Z CMC TRENDED MUCH WEAKER AND WHILE IT LAGS THE
OTHERWISE VERY TIGHT AGREEMENT IN THE REMAINING DETERMINISTIC
SUITE, ITS INCLUSION WOULD NOT BE DETRIMENTAL...SO A GENERAL MODEL
BLEND IS PREFERRED FOR THIS SHORTWAVE AT ABOVE AVERAGE CONFIDENCE.
---PRIOR DISCUSSION---
NEXT SHORTWAVE CURRENTLY EXITING UT INTO CO, PER GOES-WV SUITE,
VERTICALLY STRETCHES ACROSS THE HIGH PLAINS THIS MORNING, AND THE
12Z CMC IS THE GREATEST AMPLIFICATION WITHIN THE SUITE AND REMAINS
SO LIFTING THROUGH THE UPPER MIDWEST INTO THE NORTHERN GREAT LAKES
IN AN OTHERWISE SOLID AGREEMENT. AS SUCH, ABOVE AVERAGE
CONFIDENCE CAN BE GIVEN TO A NON-CMC BLEND FOR THIS WAVE EVEN INTO
S CANADA AND CLIPPING INTERIOR NEW ENGLAND BY EARLY NEXT WEEK.
...SHORTWAVE #3 - AMPLIFYING ALONG VANCOUVER ISLAND SUNDAY THROUGH
WY/CENTRAL PLAINS MON & GREAT LAKES BY TUES/EARLY WED...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND (WEIGHT TO GFS/ECMWF)
CONFIDENCE: AVERAGE
07Z UPDATE: THE 00Z ECWMF TRENDED SIGNIFICANTLY NORTHWARD WITH THE
SHORTWAVE ENERGY EXITING THE ROCKIES AND NOW MATCHES THE BETTER
NORTHWARD CLUSTERING OF THE GFS AND EVEN THE STRONGER UKMET/NAM
SOLUTIONS. THE 00Z CMC TRENDED THIS WAY AS WELL BUT REMAINS MUCH
WEAKER AND SHUNTS THE MOISTURE AND QPF FORCING EASTWARD UNLIKE THE
ECMWF. SO WILL FAVOR A GFS/ECMWF IN A NON-CMC BLEND TO GET VERY
CLOSE TO THE CENTER OF THE ECENS/GEFS ENSEMBLE SUITE (INITIAL
PREFERENCE. WHILE THIS IS SUBSTANTIAL CHANGE; CONFIDENCE
INCREASES BUT ONLY TO AVERAGE GIVEN THE NATURE OF LIKELY CONTINUED
RUN TO RUN VARIATION WITH SUCH A WEAK WAVE.
---PRIOR DISCUSSION---
THE NEXT SYSTEM IS A BIT STRONGER AND LONGER IN WAVELENGTH AS IT
ENTERS THE PACIFIC NW LATE TODAY INTO MONDAY. IT ALSO HAS THE
GREATEST CONNECTIVITY TO THE CENTRAL HUB/COLD AIR IN W CANADA
GIVEN THE TIMING OF IT, SO IT ALSO STRETCHES MORE INTO A WEAKLY
NEGATIVE TILT AS IT SLIDES OUT OF THE ROCKIES INTO THE CENTRAL
PLAINS BY EARLY TUESDAY. THE ECMWF, HERE THE ECMWF AND CMC ARE
FURTHER SOUTH LOADING THE TROF LIKELY DUE TO LESS CONNECTIVITY TO
THE CLOSED LOW IN SW CANADA WHILE THE GFS/NAM AND LESSER SO UKMET
SLIDE THROUGH, FURTHER NORTH AND AS IT CURLS INTO A MORE MATURE
DEEPER CYCLONE IT IS OVER LAKE SUPERIOR RELATIVE TO THE LP/LOWER
LAKES PRESENTED BY THE CMC/ECMWF. GIVEN THE CMC IS ALREADY OUT
OF PLACE DUE TO THE PRIOR SYSTEM, THIS LEAVES THE ECMWF SOLUTIONS
AS THE ONLY SOUTHWARD SOLUTIONS; THOUGH THE OPERATIONAL ECMWF IS
SOUTHWEST OF THE MAJORITY OF ECENS MEMBERS. WITH THE ISSUES THE
00Z GFS HAS WITH THE POLAR VORTEX, THE 18Z GEFS AND ECENS ARE
FAIRLY CONGRUENT AND WILL PREFER A BLEND OF THE GEFS AND ECENS
MEAN SOLUTION OVER THE GFS OR ECMWF. THE NAM AND UKMET SHOW SOME
TYPICAL LATE DAY 2/3 OVER AMPLIFICATION WHICH SEEMS LESS LIKELY
GIVEN A GREATER STRETCHED/ELONGATED TROF IN FAST FLOW IS MORE
LIKELY. SO WILL PREFER A 18Z GEFS/12Z ECENS MEAN BLEND AT
SLIGHTLY BELOW AVERAGE CONFIDENCE FOR THIS SHORTWAVE.
...SHORTWAVE #4 - REACHING OR/N CA LATE MONDAY/EARLY TUES INTO S
PORTIONS OF NORTHERN PLAINS WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE
07Z UPDATE: THE 00Z ECMWF SHOWED LITTLE CHANGE THOUGH WAS A BIT
SLOWER AND AMPLIFIED EJECTING OUT INTO THE NORTHERN PLAINS
RELATIVE TO THE FASTER GFS. THE UKMET TRENDED MUCH CLOSER TO THIS
EVOLUTION, A BIT BETWEEN THE GFS AND ECMWF IN TIMING. THE CMC
INITIALLY TRENDS WELL THROUGH THE WEST COAST, BUT MUCH LIKE THE
00Z NAM, IS VERY STRONG/COMPACT WITH THE WAVE IN THE NORTHERN
PLAINS, SO WILL REMOVE BOTH FROM THE PREFERENCE. AS SUCH A 00Z
GFS/UKMET/ECMWF BLEND IS PREFERRED BUT REMAINS ONLY AT AVERAGE
CONFIDENCE OVERALL.
---PRIOR DISCUSSION---
THE NEXT SHORTWAVE SLIDES UNDER THE OMEGA BLOCK IN ALASKA AND
QUICKLY THROUGH THE GULF OF AK TOWARD THE OR/N CA BY LATE MONDAY.
HERE, THE DISTANCE TO THE CLOSED UPPER LOW IN CANADA IS NOT
INFLUENCING ITS TRACK. THE 00Z NAM IS FLATTER AND FAST, WHILE THE
00Z CMC SHOWS GREATEST AMPLIFICATION. THE UKMET IS FAST, TYPICAL
OF BIAS WITH THE NAM WHILE THE ECMWF/GFS ARE TIMED AND SHAPED VERY
WELL IN THE MIDDLE OF THE SUITE INCLUDING A BULK OF THE ENSEMBLES
TO HAVE AVERAGE CONFIDENCE IN A GFS/ECMWF BLEND. BUT THIS SYSTEM
IS WELL OUT IN THE DATA VOID OF THE PACIFIC/EASTERN ASIA TO HAVE
TREMENDOUS CONFIDENCE.
..SHORTWAVE #5 - SHARPENING SHORTWAVE NEAR PACIFIC NW COAST WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM/ECMWF BLEND WITH LOWER WEIGHTED INCLUSION OF
THE 00Z GFS
CONFIDENCE: AVERAGE
07Z UPDATE: THE 00Z ECMWF TRENDED A BIT MORE AMPLIFIED AT 15.12Z,
VERY SIMILAR TO THE 00Z NAM, AND WHILE THE UKMET REMAINS VERY
SIMILAR TO THE 12Z RUN, IT APPEARS A BIT TOO FAR SOUTH; WHILE THE
CMC IS FAST STILL, BUT SHOWING SOME TRENDS TOWARD A CONSENSUS. SO
WILL KEEP WITH INITIAL PREFERENCE OF AN ECMWF/NAM HEAVY BLEND WITH
THE GFS AT AVERAGE CONFIDENCE.
---PRIOR DISCUSSION---
SIMILAR TO THE PRIOR SHORTWAVE, A STRONGER BUT ALSO MORE AMPLIFIED
WAVE CROSSES THE ALASKAN PENINSULA AND UPPER ALEUTIANS LATE MONDAY
INTO TUESDAY, A RELATIVELY FLAT DOWNSTREAM 'RIDGE' OR LACK
THEREOF, ALLOWS FOR GREATER BUCKLING OF THE FLOW THAT THE LEAD
PORTION OF THE WAVE SUPPORT STRONG CYCLOGENESIS BY LATE TUESDAY
INTO WED NEARING 130W. THIS IS PRESENTED BY NEARLY ALL THE
GUIDANCE WITH EXCEPTION OF THE CMC, WHICH IS UNCHARACTERISTICALLY
FAST (DUE TO NARROWED SPACING BETWEEN THE PRIOR WAVE). THE UKMET
SHOWS SOME TYPICAL NEGATIVE FEEDBACK IN THE INNER CORE, WHICH
ALLOWS FOR A SOUTHWARD DRIFT RELATIVE TO THE REMAINING GUIDANCE
AND ENSEMBLE SUITE. THE GFS IS A BIT FASTER WHILE THE NAM/ECMWF
ARE SLOWER (NAM A BIT SLOWER, BUT STRONGER). A BLEND OF THE
NAM/ECMWF AND GFS SEEMS APPROPRIATE BUT HEDGING TOWARD THE
ECMWF/NAM GIVEN THE GFS MAY BE SHOWING FAST BIAS. UNCERTAINTY, IS
OBVIOUSLY HIGH GIVEN THE PROGRESSIVE FLOW, BUT THE AGREEMENT EVEN
AT 84HRS IS HIGH ENOUGH TO HAVE AVERAGE CONFIDENCE IN A NAM/ECMWF
WEIGHTED BLEND WITH THE GFS.
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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