Prognostic Meteorological Discussion
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FXUS10 KWNH 050659
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MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 AM EST FRI FEB 05 2016

VALID FEB 05/0000 UTC THRU FEB 08/1200 UTC

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

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

SHARPENING UPPER TROUGH CROSSING THE LOWER MID-ATLANTIC ON FRIDAY
MORNING
SURFACE WAVE DEVELOPING OFF THE OUTER BANKS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

UNSURPRISINGLY NEARING THE 00HR...MODELS CONTINUE TO REFINE AND
TIGHTEN THE CLUSTER.  GIVEN THE ORIENTATION OF THE SHARPENED
SHORTWAVE LIFTING UP THE EASTERN SEABOARD...THE SURFACE LOW
ENSEMBLE CLUSTER REMAINS ELONGATED SW TO NE ALONG THE SOUTHEASTERN
COAST DURING DEVELOPMENT ALONG THE LINGERING FRONTAL ZONE.  THE
12Z ECMWF WAS THE ONLY OPERATIONAL MODEL OUTSIDE THE VERY TIGHT
CLUSTERING DEVELOPING ON THE SOUTHERN PERIPHERY BUT WITH A BETTER
CLUSTER FROM THE 00Z RUN FURTHER SOLIDIFYING AN OPERATIONAL BLEND
PREFERENCE AT ABOVE AVERAGE CONFIDENCE.


SPLIT FLOW OVER THE CENTRAL U.S. ON FRIDAY AND STRENGTHENING
SOUTHERN STREAM FEATURE EXITING THE SOUTHEASTERN U.S. COAST BY
07/1800Z ALONG WITH ATTENDANT LOW PRESSURE DEVELOPMENT OFF THE
GA/SC COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM/GFS BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THE SPLIT FLOW CURRENTLY TRACKING THROUGH THE ROCKIES AND EASTERN
SIDE FOOTHILLS CONTINUES TO PROGRESS THROUGH THE CENTRAL PORTION
OF THE PLAINS GAINING FURTHER AMPLITUDE INTO THE SOUTHERN PLAINS
BY SAT.  AT THIS POINT THE GUIDANCE BECOMES HIGHLY SPLIT WITH
ENSEMBLE SPAGHETTI PLOTS SHOWING VERY STRONG CLUSTERING HOWEVER
WITHIN THEIR OWN CAMPS.  THE 12Z/18Z GFS AND GEFS CONTINUED TO
LEAD THE PACK AND CONTINUE TO ADVANCE WHILE BEING A BIT LESS
AMPLIFIED AND CUT-OFF COMPARED TO THE MUCH SLOWER ECMWF CAMP.  THE
CMCE IS CLOSER TO THE GEFS FASTER/SHALLOWER CAMP THOUGH THE
OPERATIONAL SIGNIFICANTLY LAGS ITS MEAN AND IS NEARLY HALF WAY
BETWEEN THE TWO CAMPS.  SIMILARLY THE 12Z UKMET WAS SLOWEST BUT
HAS BEEN TRENDING TOWARD A FASTER SOLUTION NOW ECLIPSING THE 12Z
ECMWF IN PACE.  RUN TO RUN CONSISTENCY FAVORS THE ECMWF BUT THE
ECMWF TENDENCY OF BEING SLOW AND CONSOLIDATED BARES SOME
QUESTIONING OF PARTICULARLY GIVEN THE OVERALL PROGRESSIVE
WINTER/STRONGER FLOW PARTICULARLY WITHOUT ANY BLOCKING AGENT.

THE 12Z NAM TRENDED TOWARD THIS MIDDLE GROUND THOUGHT BEING A
INITIALLY A BIT MORE PROGRESSIVE AND WEAKER BEFORE CONSOLIDATING
OFF THE GA/SC COAST SUNDAY NIGHT.  THE 00Z GFS KEPT WITH THE
SHALLOWER INFLECTION OF THE WAVE DIGGING ACROSS THE SOUTH BUT ALSO
SLOWED CONSIDERABLY FROM PRIOR RUNS AND THE GEFS MEAN IN A VERY
SIMILAR TREND TO THE 00Z NAM.  OVERALL CONFIDENCE IN A MIDDLE
GROUND SOLUTION SEEMS LOGICAL GIVEN THE OVERALL FLOW REGIME
HOWEVER...WITH INCONSISTENT MODELS REPRESENTING THIS; CONFIDENCE
OVERALL IS FAIRLY LOW.  AS SUCH A 00Z NAM/GFS/12Z CMC A GOOD
COMPROMISE AT THIS TIME WHILE PLAYING SOME DUE RESPECT TO THE
OLDER GUIDANCE INCLUDING THE 12Z/18Z GFS AND GEFS AND 12Z ECENS.
CONFIDENCE IS SLIGHTLY BELOW AVERAGE.

07Z UPDATE: THE 00Z GEFS IS A NICE COMPROMISE OF THE 00Z NAM/GFS
EVOLUTION PROVIDING SOME ADDITIONAL CONFIDENCE IN THIS SOLUTION.
THE 00Z UKMET ALSO IS FAIRLY GOOD IN PLACEMENT/TIMING OF THE WAVE
AND SURFACE CYCLOGENESIS OFF THE SOUTHEAST COAST BUT ALSO BECOMES
VERY STRONG/DEEP IN COMPARISON TO THE GFS IN PARTICULAR BUT ALSO
THE NAM.  THE 00Z ECMWF TRENDED A BIT WEAKER BUT REMAINS THE SLOW
OUTLIER PARTICULARLY WEST IN THE SURFACE CLUSTER.  THE 00Z CMC
KEPT WITH TIMING BUT EVOLVED A BIT DEEPER WITH INCREASED NEUTRAL
TO NEGATIVE TILT LEADING TO A SURFACE DEVELOPMENT ON THE NORTHERN
AND WESTERN FRINGE BY THE END OF THE PERIOD.  ALL CONSIDERED A
BLEND OF THE 00Z NAM/GFS IS PREFERRED WITH LITTLE CHANGE IN
CONFIDENCE.


NORTHERN STREAM AMPLIFICATION CLIPPING THE GREAT LAKES SAT AND NEW
ENGLAND SUN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL BLEND PRIOR TO 07/00Z
            00Z UKMET/CMC/GFS BLEND AFTER
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
    BELOW AVERAGE

CYCLONE CURRENTLY OVER CONTINENTAL NUNAVUT SINKS SOUTH WHILE
AMPLIFYING/PHASING WITH SHORTWAVE ENERGY ORIGINATING OUT OF THE
YUKON BOTTOMING OUT ACROSS THE GREAT LAKES SAT AND SLIDING EAST
INTO NORTHERN NEW ENGLAND SUNDAY.  THERE IS FAIRLY SOLID AGREEMENT
WITH THE WAVE OVERALL THROUGH SAT INCLUDING THE SURFACE INFLECTION
DEVELOPING NEAR LAKE SUPERIOR SAT MORNING...AT THIS POINT THE NAM
AND LESSER SO THE 12Z CMC ARE A BIT DEEPER AND THEREFORE SLOWER
WHILE THE 12Z ECMWF AND 00Z GFS BECOME FLATTER AND FASTER; THIS IS
OUT OF CHARACTER FOR THE ECMWF BRINGING IT INTO MORE QUESTION
(ESPECIALLY WITH OTHER ISSUES ELSEWHERE) AND THIS WAS A
SIGNIFICANT SHIFT FOR THE 00Z GFS WELL OUTPACING THE DEEPER GEFS
MEAN.  THE 12Z UKMET IS MOST IN THE MIDDLE GROUND AND HAS SOME
SUPPORT FROM THE SREF...WHICH WAS IN THE PRIOR PREFERENCE.
CONFIDENCE AND MODEL AGREEMENT IS STRONG ENOUGH PRIOR TO 07/00Z TO
SUPPORT AN OPERATIONAL MODEL BLEND AT SLIGHTLY ABOVE AVERAGE
CONFIDENCE UNTIL THE MORE RELIABLE GFS/ECMWF SHIFT AWAY FROM
CONTINUITY AND THEIR NORMAL CHARACTERISTICS...BRINGING BELOW
AVERAGE CONFIDENCE IN A 12Z UKMET/CMC AND 00Z NAM BLEND TO BEST
REPRESENT THE ENSEMBLE SPREAD WHILE ALSO KEEPING SOME CONTINUITY
FROM PRIOR PREFERENCES.

07Z UPDATE: A SLIGHT QUICKENING OF THE CMC AND UKMET BETTER
CLUSTER TO THE GFS THAN THE 00Z NAM AFTER 07/00Z...YET THE 00Z
ECMWF ALSO IS SLIGHTLY FASTER AND FLATTER AND OUT OF PHASE WITH
OTHER GUIDANCE.  WILL SHIFT SOME MORE TOWARD THE FASTER SOLUTION
INCLUDING THE GFS AND REMOVING THE SLOWER NAM.  AS SUCH A 00Z
UKMET/CMC/GFS BLEND IS PREFERRED AFTER 07/00Z STILL BELOW AVERAGE.


PACIFIC SYSTEM AFFECTING THE NORTHWESTERN CONUS ON FRIDAY
TRANSVERSING THE ROCKIES AND  GAINING AMPLITUDE AND BREADTH INTO
LARGE SCALE CYCLONE OVER THE MIDWEST BY MONDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~
PREFERENCE: 00Z GEFS
CONFIDENCE: SLIGHTLY BELOW AVERAGE

MODELS ARE FAIRLY GOOD AGREEMENT WITH THE TIMING/SHAPING OF A
FAIRLY PROGRESSIVE WAVE ENTERING THE PACIFIC NORTHWEST FRIDAY
EVENING/SATURDAY MORNING WITH ONE EXCEPTION...THE 12Z ECMWF WHICH
IS A BIT FLATTER AND HAS A DIFFERENT THERMAL PROFILE IN THE 850-7H
LAYER BEING A BIT WARMER THROUGHOUT BUT PREDOMINANTLY ON THE
LEADING EDGE.  AS THE WAVE PROGRESSES ACROSS THE ROCKIES IT BEGINS
TO AMPLIFY INTO A LARGER SCALE DEEP CYCLONE ACROSS THE UPPER MS
RIVER VALLEY INTO THE MIDWEST BY THE END OF THE FORECAST PERIOD.
THE ECMWF IS GENERALLY THE FLATTEST/MOST PROGRESSIVE GIVEN A MUCH
FASTER/UNCHARACTERISTICALLY FAST DOWNSTREAM TROF VACATING THE
GREAT LAKES AND THEREFORE IS ON THE NORTHEASTER EDGE OF THE MODEL
SUITE. ON THE OTHER SIDE IS THE GUIDANCE THE 12Z UKMET CENTROID IS
NEAR THE ECMWF BUT ALSO IT ALSO AMPLIFIES THE MOST ALONG THE
CENTRAL ROCKIES MAKING IT GENERALLY BROADER AND SYMMETRIC BY THE
END OF THE FORECAST PERIOD WITH STRONGER JET STRUCTURE FURTHER
WEST.  THE 12Z CMC AND 00Z NAM/GFS ARE MOST CENTRAL IN THE OVERALL
SHAPE/TIMING/EVOLUTION OF THE LARGER SCALE TROF BUT INTERNALLY TO
THE TROF ALOFT THE 00Z NAM/GFS REMAIN ON THE WESTERN SIDE OF THE
BEST PACKING AND THIS IS REFLECTED WELL IN THE SURFACE LOW TRACK
EVEN BOTH BEING EVEN FURTHER SOUTHWEST THAN THE 21Z SREF AND 18Z
GEFS.  AT THIS TIME PREFERENCE TOWARD THE MIDDLE GROUND BEST
REPRESENTED BY THE 18Z GEFS CAN BE BEST REPRESENTED BY A BLEND OF
THE 12Z CMC WHICH WILL TEMPER THE SW NATURE OF THE 00Z NAM/GFS.
OVERALL CONFIDENCE IS ACTUALLY QUITE HIGH IN THE AVERAGE LARGER
SCALE TROF BUT THESE INTERNAL DIFFERENCES IN PLACEMENT OF THE KEY
WAVES/PRESSURES LEAD TO AN OVERALL CONFIDENCE SLIGHTLY BELOW
AVERAGE IN THE 00Z NAM/GFS AND 12Z CMC BLEND.

07Z UPDATE: THE 00Z GEFS REMAINS MOST CENTRAL OF THE GUIDANCE AND
IS PREFERRED...THE 00Z ECMWF REMAINED FLATTER ENTERING THE PAC NW
AND FAST ALONG THE US/CANADA BOARDER AND SHIFTS SOUTH SIMILAR IN
EVOLUTION TO ITS 12Z RUN BUT NOT AS FAR EAST AND CLOSER TO THE 12Z
ECENS MEAN BUT STILL ON THE RIGHT SIDE OF IT AND IS QUITE
ELONGATED NORTH TO SOUTH.  THE 00Z CMC SHIFTED FROM THE NAM/GFS
SUPPORT TO CLOSER TO THE ECMWF WITH A SURFACE LOW TRACK THROUGH
THE WESTERN GREAT LAKES RATHER THAN ALONG THE UPPER MS RIVER
TRACK.   THE 00Z UKMET BACKED OFF THE BROAD SYMMETRIC WAVE AND IS
MORE MIDDLE GROUND TO THE CMC/ECMWF AND NAM/GFS...HOWEVER IS ABOUT
3-6HRS SLOWER THAN BOTH CAMPS.  WITH THE CMC`S SHIFT AWAY FROM THE
EARLIER PREFERENCE THE NAM/GFS IS ON THE WESTERN SIDE OF THE
GUIDANCE SUITE TO PREFER IT OUTRIGHT...AS SUCH WILL PREFER THE 00Z
GEFS AS A COMPROMISE TO A MORE CENTRAL SOLUTION.

...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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