Prognostic Meteorological Discussion
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000
FXUS10 KWNH 090652
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
151 AM EST TUE FEB 09 2016

VALID FEB 09/0000 UTC THRU FEB 12/1200 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

00Z GUIDANCE EVALUATION INCLUDING MODEL PREFERENCE AND FORECAST
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

LONGWAVE TROF ACROSS THE EASTERN THIRD OF THE U.S LIFTING OUT BY
WED
ASSOCIATED SURFACE LOWS OVER THE E GREAT LAKES/THE MID-ATLANTIC
COAST TUESDAY/WEAK LOW S OF LONG ISLAND WED MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/ECMWF/UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

LARGE SCALE DIFFERENCES ARE CONTINUING TO BECOME BETTER RESOLVED
WITH AN OVERALL MODEL AGREEMENT THROUGH THE TROF`S EVOLUTION
INCLUDING ITS FILLING AND LIFTING NORTHEASTWARD BY THE END OF THE
FORECAST PERIOD.  THE 12Z CMC IS THE ONLY MAJOR OUTLIER IN THIS
RESPECT FILLING A BIT QUICKER THAN THE REST OF THE GUIDANCE
INCLUDING THE 18Z GEFS AND 12Z ECENS ENSEMBLE SPREAD BUT NOT
SIGNIFICANTLY SO TO DISREGARD IT.   THE DIFFERENCES REMAIN TIED TO
INTERNAL WAVE TIMING/STRENGTH DIFFERENCES BUT EVEN THESE ARE
STARTING TO COME TO BETTER AGREEMENT.  THE SIGNIFICANT DIFFERENCES
APPEAR MOSTLY WITH RESPECT TO THE INITIAL COASTAL DEVELOPMENT
EXITING THE VA COAST THIS MORNING...WITH THE 00Z NAM/12Z CMC AND
12Z UKMET DEVELOPING INITIALLY EAST AND SOUTH OF FAIRLY STRONG
GEFS/ECENS SURFACE CLUSTER (THE CMCE CLUSTER DOES SUPPORT THESE
SOLUTIONS - BUT EVEN THE OPERATIONAL IS ON THE SE SIDE OF THAT
CLUSTER).  THE ECMWF MEMBERS COMPOSE THE MAJORITY OF THE WESTERN
MEMBERS THOUGH THE OPERATIONAL IS ON THE EAST SIDE OF THOSE
MEMBERS VERY CLOSE TO THE GFS AND GEFS MEMBERS.  THE 12Z UKMET IS
CLOSER TO THE GFS/ECMWF AND ALSO DEVELOPS IN A SIMILAR MANNER AND
TIMING/STRENGTH COMPARED TO THE WEAKER CMC/NAM SOLUTIONS.  SOME OF
THESE DIFFERENCES LEAK INTO THE TRAILING PRESSURE TROF AND
SUBSEQUENT CYCLOGENESIS SOUTH (EAST) OF LONG ISLAND WED MORNING
WITH THE ECMWF WEAKEST AND SLOWEST TO DEVELOP THIS LOW ALSO BEING
ON THE SOUTHERN PACKING BUT WITHIN PROXIMITY TO THE GFS.  MODELS
ARE ALL IN STRONG AGREEMENT WITH THE LINGERING SURFACE LOW ACROSS
THE GREAT LAKES INTO NEW ENGLAND THROUGH WED NIGHT/THUR MORNING.
COULD SUPPORT A NON-CMC BLEND OVERALL BUT WITH TIGHT AGREEMENT IN
TIMING/PLACEMENT AND FOR THE MOST PART STRENGTH OF ALL MAIN
FEATURES...WILL SUPPORT THE GFS/ECMWF/UKMET BLEND THAT IS STRONGLY
SUPPORTED BY THE 18Z GEFS/12Z ECENS MEAN PACKING.  CONFIDENCE IS
SLIGHTLY ABOVE AVERAGE IN THIS BLEND.

07Z UPDATE: LITTLE INTERNAL SHIFTS IN THE 00Z ECMWF KEEP FAIRLY
STRONG AGREEMENT WITH THE 00Z GFS. THE 00Z UKMET WAS ON THE SLOW
SIDE WITH THE COASTAL LOW AND A BIT SLOWER WITH THE LEE SURFACE
WAVE SE OF LONG ISLAND TO MAKE IT A BIT LOOSER OF AN OVERALL FIT
BUT THIS IS MINOR COMPARED TO THE 00Z CMC WHICH REMAINS WEAKER AND
FURTHER E WITH THE FIRST COASTAL LOW.  AS SUCH SEE NO REASON TO
DEVIATE FROM A 00Z GFS/ECMWF/UKMET BLEND AT SLIGHTLY ABOVE AVERAGE
CONFIDENCE.


ARCTIC CUT-OFF/COLD SURGE ENTERING THE NORTHERN GREAT
LAKES/ARROWHEAD OF MN FRI MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

IN THE WAKE OF THE FILLING LARGE SCALE TROF ACROSS THE EASTERN
U.S...A STRONG WAVE IS DEEPENING ACROSS THE NORTH POLE TODAY WHICH
WILL DROP SOUTH AND DEEPEN THE ARCTIC VORTEX BUILDING A DEEP POOL
OF ARCTIC COLD ACROSS HUDSON BAY THURS AND JAMES BAY BY FRIDAY
MORNING.  OVERALL THE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE
TIMING OF THE WAVE.  THE 12Z CMC IS MOST OUT OF PHASE WITHIN THE
LARGE SCALE ENSEMBLE SPAGHETTI PLOT...THIS IS CONTRIBUTED TO A FEW
FACTORS.  IT IS THE DEEPEST LOW (ALMOST 60 DM MORE THAN THE
REST/CONSENSUS) CONTRIBUTED BY THE COLDEST OF THE GUIDANCE THOUGH
ALSO IS QUITE BROAD WITH THAT COLD POOL WEST TO EAST --- THIS
ALLOWS FOR A BROADER UPPER LEVEL WAVE EXTENDING WEST TO LAG ACROSS
BOREAL CANADA COMPARED TO THE OTHER GUIDANCE. THOUGH THE 12Z
ECMWF/UKMET ARE ALSO SLIGHTLY WEST COMPARED TO THE 00Z NAM/GFS
WITH RESPECT TO THE INNER CORE OF THE UPPER LOW AND COLD
POOL;THOUGH THE 00Z GFS ALSO DID TREND A BIT EAST OF THE 12Z/18Z
GEFS INCREASING SPACING WITH THE ECMWF/UKMET BY THE END OF THE
FORECAST PERIOD...IT IS NOT LARGE ENOUGH TO FAVOR ON CAMP OVER THE
OTHER.  MAINLY DUE TO THE DIFFERENCES IN DEPTH/SHAPE OF THE UPPER
LOW...WILL FAVOR A NON-CMC BLEND AND WITH OVERALL SMALL SPREAD
CONFIDENCE IS FAIRLY HIGH...SLIGHTLY ABOVE AVERAGE.

07Z UPDATE: SMALL DIFFERENCES IN THE 00Z CMC SEEM TO HAVE RESOLVED
WITH A MUCH BETTER SHAPE TO THE WAVE OVERALL AND COLD POOL/THERMAL
FIELDS THOUGH FAVORING THE SLIGHT WESTWARD PACKING OF THE 00Z
ECMWF/UKMET THAN THE GFS/NAM...THOUGH THIS DETAILS ARE SMALL
ENOUGH BY DAY 3 TO SUPPORT AN OPERATIONAL MODEL BLEND FOR THIS
WAVE AT SLIGHTLY ABOVE AVERAGE CONFIDENCE.


WEAK LOW PRESSURE MOVING FROM MONTANA TO TEXAS WED-THU
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 12Z ECMWF SHIFTED FASTER AND IS REMAINS GENERALLY WEAKER AND
WEST COMPARED TO THE REST OF THE GUIDANCE AND THOUGH THE 12Z ECENS
MEAN TRENDED THIS WAY TOO...IT WAS NOT AS DRAMATIC AND IS CLOSER
PACKED TO THE 12Z CMC/00Z NAM/GFS/UKMET AT THE SURFACE. THE 12Z
CMC IS STRONGER WITH THE WAVE AND HAS IS A BIT MORE ROBUST IN
MOISTURE AND THEREFORE ASSOCIATED QPF SWATH OUT OF SASKATCHEWAN
INTO THE NORTH RED RIVER VALLEY AND ALSO LINGERS INTO THE OH/MS/TN
RIVER CONFLUENCE AREA. THE 12Z UKMET IS TIMED A BIT FASTER ALOFT
THAN THE GFS/NAM/CMC BUT TRACKS WELL WITH AT THE SURFACE AND
WITHIN THE QPF AXIS.  THE 00Z GFS REMAINS QUITE CONSISTENT RUN TO
RUN THOUGH DID SHIFT SLIGHTLY TO A DEEPER AND EASTWARD TRACK AT
THE SURFACE LIKE THE 12Z CMC...AND AS SUCH WILL FAVOR WITH SUPPORT
OF THE GEFS A NON-ECMWF BLEND AT AVERAGE CONFIDENCE.

07Z UPDATE: THE 00Z ECMWF SLOWED A BIT AND IS IN LINE WITH THE 12Z
ECENS MEAN; THOUGH IT IS FASTER AND SLIGHTLY WEAKER THAN THE OTHER
GUIDANCE...ITS TRACK AND QPF SWATH ARE MUCH BETTER ALIGNED OVERALL
TO SUPPORT AN OPERATIONAL MODEL BLEND.  A LITTLE STRENGTHENING
WITH THE 00Z UKMET MATCHING THE 12Z CMC AND 00Z GFS...WHILE THE
00Z CMC WEAKENED A BIT...ALL TOGETHER THE SPREAD IS REDUCING FOR A
SLIGHTLY ABOVE AVERAGE CONFIDENCE IN THE OPERATIONAL MODEL BLEND.


DUAL SHORTWAVE PACK GLANCING THE PACIFIC NORTHWEST WED
DEEPER LARGE SCALE TROF APPROACHING LATE FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM/GFS/ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THE LARGE SCALE RIDGE IS WELL LOCKED INTO THE WESTERN US WHICH IS
FORCING THE PROGRESSIVE SHORTWAVES DANCING ALONG THE OUTER
PERIPHERY OF LARGE SCALE UPPER CYCLONE OVER THE NORTHERN PACIFIC
CURRENTLY.  THE LEAD WAVE WITHIN THE CYCLONE ALONG 140W IS IN
FAIRLY GOOD AGREEMENT IN TIMING DEPTH/INCLUDING THE LINGERING
CENTER THAT WILL SHEAR COMING ASHORE WED MORNING; THOUGH SPACING
WITH THE UPSTREAM KICKER IS A BIT DIFFERENT.  THE GFS IS THE MOST
REDUCED IN SPACING ALONG WITH THE 12Z UKMET WHICH IS ALSO QUITE
WRAPPED UP COMPARED TO THE CMC/ECMWF/NAM.  OVERALL AFFECTS ARE
MINOR EXCEPT OVER THE OCEAN AND GENERAL WEAKENING OF THE TOP OF
THE RIDGE...ALLOWING FOR THE ONSHORE SW ORIENTED MOISTURE FEED.
THE NEXT S/W MOVING THROUGH IS THEREFORE FASTER IN THE GFS/UKMET
BRINGING QPF TO THE NW NEARLY 6-12 HRS FASTER THAN THE SLOWER
ECMWF.  AT THIS POINT...THE GFS/UKMET RETAINED ENERGY UPSTREAM
WHICH SUPPORTS A MORE AMPLIFIED WAVE THAN THE 12Z ECMWF WHICH
PHASED THE WAVE WITH THE UPSTREAM ENERGY MAKING IT A BIT FASTER
AND LESS AMPLIFIED BY THE END OF THE FORECAST PERIOD THAN THE
GFS/GEFS.  THOUGH THE 00Z GFS DID TREND A BIT FASTER...THIS WOULD
SUPPORT MORE TOWARD THE ECMWF SOLUTION. THE 00Z NAM REMAINED IN
STRONG AGREEMENT WITH THE ECMWF TO SUPPORT A BLEND.  CONFIDENCE IS
GENERALLY LOW GIVEN THE SPREAD IN TIMING TOWARD THE END OF THE
PERIOD AND SLIGHT BUT INCREASING DIFFERENCE SEEN BETWEEN THE
OPERATIONAL ECMWF AND THE 12Z ECENS MEAN.

07Z UPDATE: STRENGTHENING AGREEMENT EXISTS WITH THE LEADING TWO
WAVES ON WED WITH STRONGER ALMOST FULL AGREEMENT WITH THE INITIAL
WAVE...BUT THE 00Z UKMET REMAINS STRONGER AND FURTHER EAST WITH
THE 00Z CMC A BIT FAST TOO LEADING A BETTER CLUSTERING OF THE 00Z
GFS/NAM/ECMWF.  THOUGH IMPACTS ARE MINOR WITH THIS WAVE...STILL
EFFECTIVELY OPENING THE ATMOSPHERIC RIVER TOWARD THE COAST AS IT
SUPPRESSES THE TOP OF THE WESTERN RIDGE.   THE MORE SIGNIFICANT
SPREAD REMAINS ON LATE THURS INTO FRIDAY AS THE 00Z UKMET IS
SLOWER BUT MUCH STRONGER/WOUND UP AND GIVEN ITS EASTERN TREND WITH
THE PRECEDING SYSTEM...THIS ALLOWS FOR A FURTHER EAST/STRONGER
MOISTURE FLUX OVERALL.  THOUGH THE 00Z GFS REMAINS FASTER AND EAST
WITH THIS WAVE THAN THE ECMWF/CMC...THE NEW 00Z ECMWF IS TRENDING
FASTER AND EAST THAN THE 12Z RUN...EVEN FURTHER OUTPACING THE 12Z
ECENS MEAN.

OVERALL THE UKMET IS MOST OUT OF PHASE BEING MUCH FASTER AND
STRONGER IN WITH MANY OF THE WAVES AND EVENTUALLY THE DEEP LAYER
TROF ON FRIDAY...THE CMC IS ALSO A BIT EASTWARD WITH THE LARGE
SCALE TROF ORIENTATION TO SUPPORT IT IN A BLEND.  THE 00Z GFS
STILL SEEMS A BIT FAST BUT WITH THE ECMWF TRENDING THIS WAY
PARTICULARLY BY DAY 3...WILL SUPPORT A 00Z NAM/GFS/ECMWF BLEND AT
SLIGHTLY BELOW AVERAGE CONFIDENCE.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

GALLINA

$$




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