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575
FXUS10 KWNH 070450
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1149 PM EST SAT FEB 06 2016

VALID FEB 07/0000 UTC THRU FEB 10/1200 UTC

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

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

NORTHERN STREAM FEATURE CLIPPING UPPER NEW ENGLAND EARLY SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

A LOBE OF THE GLOBAL ARCTIC CYCLONE CONTINUES TO TRANSLATE INTO
QUEBEC LEADING TO GLANCING  WEAK HEIGHT FALLS THROUGH UPPER
SECTIONS OF NEW ENGLAND ON SUNDAY MORNING.  OVERALL GUIDANCE
CONTINUES TO SOLIDIFY AND ARE IN GOOD AGREEMENT PARTICULARLY
ACROSS NEW ENGLAND ON SUNDAY AS SUCH AN OPERATIONAL MODEL BLEND IS
PREFERENCE AT ABOVE AVERAGE CONFIDENCE


UPPER TROUGH ACROSS THE NORTHEASTERN GULF OF MX TONIGHT LIFTING UP
THE US OFFSHORE WATERS THRU MONDAY WITH RAPIDLY DEEPENING SURFACE
LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF BLEND
CONFIDENCE: AVERAGE

DEEP UPPER LEVEL CYCLONE ACROSS ALABAMA INTO THE NORTHEAST GULF OF
MEXICO CURRENTLY WILL CONTINUE TO CONSOLIDATE BUT SWING MORE
NEGATIVE TILT AS IT LIFTS ACROSS FL UP THROUGH THE OFFSHORE WATERS
OF THE EAST COAST...A WEAK SURFACE WAVE WILL RAPIDLY DEEPEN ALONG
THE EASTERN SIDE OF THE GULF STREAM AND LIFT UP TO EAST OF NOVA
SCOTIA BY TUES MORNING.  THE 00Z NAM REMAINS ON THE WESTERN SIDE
OF THE SURFACE LOW CLUSTER DURING DEVELOPMENT OFF THE GA COAST AND
WOBBLES EAST BEFORE BECOMING MORE IN LINE WITH THE AVERAGE TRACK
UP THE COAST...BUT REMAINS GENERALLY ON THE SLOWER SIDE OF THE
GUIDANCE INCLUDING ALOFT.  THE 00Z GFS HAS TRENDED A BIT SOUTH AND
EAST WITH THIS RUN AND IS IN MUCH BETTER AGREEMENT WITH ITS GEFS
MEAN THAN PRIOR RUNS BUT ALSO IN LINE WITH THE 12Z ECENS MEAN AND
12Z ECMWF WHICH HAVE BEEN FAVORED.  THE 12Z UKMET WAS FAVORED
EARLIER BUT IS ALSO A FAST/STRONGER MEMBER ALOFT AS WELL AS AT THE
SURFACE WITHIN THE ENSEMBLE CLUSTER...AND WITH BETTER AGREEMENT IN
THE GFS/ECMWF WILL SHIFT TO THE GFS/ECMWF BLEND TO BEST REPRESENT
THE 18Z GEFS/12Z ECENS MEAN.  THE 12Z CMC IS GENERALLY A BIT
BROADER AND WEAKER THAN MUCH OF THE OTHER GUIDANCE ALOFT BUT HAS
GOOD TIMING PACING...BUT AT THE SURFACE TO 7H ITS WEAKNESS SHOWS
ON THE COASTAL SIDE OF THE MODEL CLUSTER TO NOT FAVOR IT AT THIS
TIME.   CONFIDENCE IN A 00Z GFS/12Z ECMWF BLEND IS INCREASING TO
AVERAGE.


PROGRESSIVE SHORTWAVE TRACKING ALONG THE US/CANADA BORDER
DEEPENING INTO A LARGE SCALE DEEP CYCLONE ACROSS THE GREAT LAKES
INCLUDING ASSOCIATED SURFACE LOWS IN THE GREAT LAKES AND
DEVELOPING ACROSS S MID-ATLANTIC TUE MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND THRU TO 08/12Z
            00Z NAM/12Z ECMWF BLEND
CONFIDENCE: ABOVE AVERAGE UNTIL 08/12Z...AVERAGE AFTERWARD

MODELS ARE IN FAIRLY STRONG AGREEMENT WITH TIMING/PLACEMENT OF THE
STRONG CYCLONE AS SEEN IN WV ENTERING THE DAKOTAS AND ASSOCIATED
DEEP SURFACE REFLECTION CONTINUING SOUTHEAST INTO THE WESTERN
GREAT LAKES THROUGH MONDAY MORNING. SUNDAY AFTERNOON INTO MONDAY
OVERALL SPREAD BEGINS TO INCREASE AS THE UPSTREAM SHORTWAVE ACROSS
ALBERTA WILL BEING TO ACCELERATE SE AND CONCURRENTLY CARVE OUT THE
DEEPER LARGE SCALE CYCLONE/DEEP GLOBAL TROF ACROSS THE EASTERN
THIRD OF THE U.S. BY LATE MON/TUES. THE STRONGER MODELS ARE
GENERALLY A BIT FASTER AND SHIFT THE CENTROID OF THE UPPER LOW
SOUTHEAST OVER THE UPPER OHIO RIVER VALLEY COMPARED TO THE WEAKER
ONES.  BY DAY 2 AND EVEN INTO DAY 3...THE LARGE SCALE CYCLONE
REMAINS WELL AGREED UPON BUT THE INTERNAL WAVES ARE MUCH MORE
RANDOM IN TIMING/PLACEMENT AND WILL HAVE SIGNIFICANT IMPACTS
DIFFERENCES THAT PROVIDE LOWER CONFIDENCE OVERALL IN THESE
DETAILS.  GIVEN THE RANDOM CHAOTIC NATURE OF THESE INTERNAL WAVES
FROM RUN TO RUN DETERMINISTIC RUNS IT IS PRUDENT TO FAVOR ENSEMBLE
MEANS FOR SOME STABILITY/CONTINUITY THOUGH OBVIOUSLY THIS WILL
WASH OUT MUCH OF THE MESOSCALE DETAILS THAT WILL REMAIN VERY HARD
TO LOCK DOWN.   BY TUESDAY MORNING THE NEXT INTERNAL WAVE OF THE
INNER CORE WILL SWING AROUND AND PHASE WITH PERIPHERAL SHORTWAVE
ENERGY ALONG EDGE OF THE LARGE SCALE CYCLONE AND SWING EAST
LEADING TO SURFACE CYCLOGENESIS ACROSS THE VA/NC REGION BEFORE
SHIFTING OFFSHORE WHILE DEEPENING.

THE MODEL GUIDANCE IS STRONG ENOUGH TO SUPPORT AN OPERATIONAL
MODEL BLEND UP TO 08/12Z AT ABOVE AVERAGE CONFIDENCE BEFORE THE
SPREAD STARTS TO INCREASE...THIS INCLUDES THE SURFACE LOW ACROSS
THE GREAT LAKES AND ASSOCIATED SENSIBLE WEATHER.

AFTER 08/12Z...THE 00Z GFS REMAINS FASTEST BUT HAS TRENDED WEST
INITIALLY AND WEAKER ALLOWING FOR A SLOWER AND FURTHER SOUTH SHIFT
HOWEVER IT STILL REMAINS FURTHER NORTH WITH THE CYCLONE
DEVELOPMENT AS WELL AS QPF AXIS AS SUPPORTED BY THE 18Z GEFS;
THOUGH GIVEN ITS TENDENCY FOR THE STRONGEST SOLUTION PUTS IT ON
THE NORTHERN SIDE PERIPHERY OF THE GUIDANCE.  LIKEWISE THE
ECMWF/ECENS MEAN ARE ON THE SLOWER AND WEAKER SIDE BUT HAVE BETTER
SUPPORT FROM THE 00Z NAM/12Z CMC OVERALL PROVIDING SOME ADDITIONAL
CONFIDENCE HERE BUT NOT BECAUSE IT CLEARLY HAS A LOCK ON THE
ENVIRONMENTAL SETUP, BUT MORE THAT IT HAS GREATER SUPPORT.  THE
12Z UKMET IS ON THE SLOWER BUT DEEPER EDGE OF THE GUIDANCE
INCLUDING THE ENSEMBLE SPREAD...WHICH RESULT IN A SIMILAR SLOWER
BUT STRONGER SURFACE REFLECTION OFFSHORE BY TUESDAY NIGHT/WED
THOUGH BETTER CLUSTERED WITH ALL BUT THE GFS/GEFS.  AS SUCH WILL
FAVOR A 00Z NAM/12Z ECMWF BLEND TO REPRESENT THE 12Z ECENS
MEAN...AND WITH THE GFS TRENDING TOWARD THESE
SOLUTIONS...CONFIDENCE IS RAISED BUT ONLY TO AVERAGE OVERALL.


GLANCING AFFECTS ACROSS PACIFIC NW COAST OF NORTH MOVING SHORTWAVE
TUES NIGHT/WED MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/12Z ECMWF BLEND
CONFIDENCE: AVERAGE

A SHORTWAVE LIFTS UP THE WESTERN PERIPHERY OF THE WELL ESTABLISHED
WEST COAST RIDGING BY TUE NIGHT INTO WED...MORE OR LESS BREAKING
DOWN THE INTENSITY OF THE RIDGE ACROSS THE NORTHWEST INTO WED
MORNING.  SPAGHETTI DIAGRAMS ARE TRENDING TO A BROADER TROF BUT
THE TIMING OF THE EMBEDDED MORE AMPLIFIED SHORT REMAIN QUITE LARGE
WITH THE ECMWF ENSEMBLE MEMBERS WELL PACKED BUT ALMOST HALF A
WAVELENGTH IN ADVANCE OF THE MORE SPREAD GEFS MEMBERS WITH CMCE
MEMBERS INTER-SPACED BETWEEN WITH THE CMCE MEAN SLOWER TOWARD THE
GEFS TIMING. THE 00Z NAM IS ALSO ON THE SLOWER SIDE OF THE
GUIDANCE.  THE 12Z ECMWF DID TREND A BIT SLOWER THAN YESTERDAY`S
00Z RUN AND THE FLATTER 12Z ECENS MEAN...AND THE 00Z GFS TRENDED
FASTER TOWARD THE 12Z ECMWF.  THE 12Z CMC LIKE ITS MEAN IS
SHALLOWER IN AMPLITUDE WITH THE LEADING WAVE BUT DEEPER WITH A
SECONDARY FLATTER WAVE. THE 12Z UKMET APPEARS IN LINE WITH TIMING
BUT IS SHIFTED A BIT FASTER BUT ALSO FURTHER EAST TOWARD THE COAST
BY 10/12Z.  BEST PACKING OF THE MORE RELIABLE GFS/ECMWF
MODELS...EVEN CLOSER THAN THEIR MEANS...WHILE TRENDING TOWARD EACH
OTHER BUILDS SOME CONFIDENCE IN BLENDING THE 00Z GFS/12Z ECMWF AT
AVERAGE CONFIDENCE FOR THIS WAVE.


...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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