Prognostic Meteorological Discussion
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FXUS10 KWNH 221713
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1210 PM EST WED FEB 22 2017

VALID FEB 22/1200 UTC THRU FEB 26/0000 UTC

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

12Z NAM/GFS EVALUATION INCLUDING PRELIMINARY PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...SOUTHERN STREAM CLOSED LOW EVOLUTION FROM THE FL PANHANDLE TO
THE FL KEYS TODAY...
...FEATURE WEAKENING AND LINGERING OFF THE SOUTHEAST COAST THROUGH
EARLY SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

MID TO LATE MORNING WV IMAGERY CONTINUES TO FEATURE AN EVOLVING
CLOSED UPPER LOW ALONG AND JUST OFFSHORE OF THE EASTERN GULF
COAST. EMBEDDED IN THE UPPER LOW AXIS IS A LOBE OF VORTICITY
ORIENTED JUST SOUTH OF THE FLORIDA PANHANDLE. IT IS THIS FEATURE
THAT WILL BECOME DOMINANT...FORCING THE SURFACE LOW SE ACROSS
SOUTH FL TODAY...EVENTUALLY WOBBLING ALONG AND NORTH OF THE STRAIT
OF FLORIDA TO A POSITION NEAR THE NW BAHAMAS LATE
TONIGHT...MEANDERING THERE IN WAIT FOR THE MAIN VORT FEATURE TO
BOTTOM OUT THROUGH THE MEAN TROUGH AND START TO FILL THROUGH THU.
FROM THURSDAY NIGHT ON...THE WEAKENING WAVE LIFTS NORTHEAST TOWARD
BERMUDA FROM FRI INTO EARLY SAT. OVERALL...THE GUIDANCE REMAINS IN
GOOD AGREEMENT WITH THE OVERALL SYNOPTIC PATTERN...WITH SMALL
DIFFERENCES WITH SPECIFIC DETAILS SUCH AS EXACT POSITION OF THE
SURFACE LOW AS IT WOBBLES OFF THE FL COAST.

THE 12Z NAM AND THE 12Z NAM PARALLEL EACH TRENDED A BIT QUICKER
WITH THE FILLING UPPER TROUGH FRI/SAT...AND IS ALSO A BIT MORE
PROGRESSIVE WITH THE ASSOCIATED SURFACE LOW...WHICH IS A TREND
TOWARD THE REST OF THE GUIDANCE. THE NAM SOLUTION NOW MESHES
REASONABLY WELL WITH THE 12Z GFS...ALTHOUGH THE NAM SOLUTION IS A
BIT STRONGER FRIDAY NIGHT/EARLY SATURDAY. THE 00Z ECMWF AND 00Z
CMC ARE EACH SLIGHTLY WEAKER/FASTER WITH THE SURFACE LOW...WITH
THE 00Z UKMET ESSENTIALLY IN BETWEEN THE TWO SOLUTIONS. THE 06Z
NAEFS HAS TRENDED TOWARD THE NCEP MODEL CONSENSUS...WHICH COULD
PORTEND TO THE 12Z CMC  TRENDING TOWARD THE CONSENSUS SOLUTION AS
WELL. GIVEN THE 12Z TRENDS FROM NAM/GFS...A GENERAL MODEL BLEND
CAN NOW BE SUPPORTED AT ABOVE AVERAGE CONFIDENCE.

...SHORTWAVE LIFTING OUT OF NORTHERN ROCKIES INTO THE UPPER
MIDWEST....
...ASSOCIATED SURFACE LOW TRACKING ACROSS THE GREAT LAKES TONIGHT
AND CLIPPING N NEW ENGLAND THU NIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

LATE MORNING WV IMAGERY SHOWS THE ELONGATED SHORTWAVE ENERGY
SWINGING ACROSS THE DAKOTAS...SUPPORTING A WEAK SURFACE REFLECTION
THAT WILL CONTINUE TO LIFT ACROSS THE UPPER MIDWEST THROUGH TODAY.
THE 12Z NAM CONTINUED TO LEAN TOWARDS A MORE PROGRESSIVE SOLUTION
WITH THIS SYSTEM...IN LINE WITH THE 00Z ECMWF SOLUTION. THE 12Z
GFS LIKEWISE TRENDED FASTER/FLATTER ALOFT TOWARDS THE CONSENSUS
SOLUTION...AS DID THE 00Z CMC. THE 00Z UKMET IS SLIGHTLY MORE
AMPLIFIED INITIALLY...BUT OVERALL DIFFERENCES ARE MINOR.
OVERALL...THE TRENDS/WV MOSAIC SETUP CONTINUE TO SUPPORT A FLATTER
AND FASTER EVOLUTION...AND MODEL GUIDANCE IS INDEED TRENDING IN
THIS DIRECTION. WILL FAVOR A GENERAL MODEL CONSENSUS AT JUST ABOVE
NORMAL CONFIDENCE.

...BROAD LONGWAVE TROF CROSSING THE INTERMOUNTAIN WEST THU/FRI...
...DEVELOPING CLOSED LOW OVER MIDWEST LATE FRI INTO SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/ECENS / 12Z GFS
CONFIDENCE: AVERAGE

LATEST WV IMAGERY FEATURES SEVERAL PERTURBATIONS ROUNDING THE BASE
OF A POSITIVELY TILTED UPPER TROUGH...WHICH IS IN THE PROCESS OF
COMING ASHORE WEST COAST. JUST UPSTREAM...A STRONGER PIECE OF
SHORTWAVE ENERGY IS DIGGING SOUTH OFFSHORE OF THE WA/OR COASTLINE.
THIS FEATURE WILL CARVE OUT A MORE BROAD UPPER TROUGH ACROSS THE
INTERMOUNTAIN WEST BY EARLY THURSDAY MORNING....WITH A
STRONGER/MORE CONCENTRIC UPPER LOW EVENTUALLY SETTING UP ACROSS
THE MIDWEST BY FRIDAY MORNING. ON THE HEELS OF THE RESULTANT
HEIGHT FALLS...INCREASINGLY NEGATIVE TILT/HIGHLY DYNAMIC
DIFFLUENCE WILL RESULT IN RAPID SURFACE CYCLOGENESIS OF THE
SURFACE WAVE ALONG A FRONTAL ZONE EXTENDING FROM WESTERN KS INTO
THE MID MISSISSIPPI VALLEY. THE SURFACE LOW IS EXPECTED TO THEN
FOLLOW THE FRONTAL ZONE OUT OF WEST-CENTRAL KS INTO SOUTHERN IA BY
FRIDAY MORNING. PLEASE REFER TO THE WPC QPFPFD AND QPFHSD (HEAVY
SNOW/QPF DISCUSSIONS)...AS WELL AS LOCAL NATIONAL WEATHER SERVICE
OFFICE PRODUCTS FOR MORE LOCATION SPECIFIC INFORMATION ON
ASSOCIATED SNOW...WIND AND OTHER HAZARDS.

AS FOR MODEL DETAILS...THE 12Z NAM/GFS HAVE CONTINUED THEIR
GRADUAL TREND TOWARD THE ECMWF SOLUTION....THOUGH BOTH MODELS AND
THEIR RESPECTIVE PARALLEL SOLUTIONS...REMAIN DISPLACED A BIT TO
THE NORTH WITH THE SURFACE LOW AND DEFORMATION ZONE...MORE SO WITH
THE NAM AND NAM PARALLEL.  THE 00Z UKMET AND CMC TRENDED
INCREMENTALLY FASTER BUT ARE STILL LAGGING AND SLOW WITH THE UKMET
BEING THE BIT DEEPER/SLOWER OF THE TWO. THE 00Z ECMWF FAVORED
TOWARD A TRIPLE POINT SOLUTION INTO THE GREAT LAKES BY FRIDAY
NIGHT/EARLY SAT...THE 12Z GFS CONTINUES TO DEPICT A STRONGER
SURFACE/OCCLUDED LOW SOLUTION...AN IDEA TO WHICH THE 00Z NAM...AND
INTERESTINGLY THE 06Z NAEFS BOTH TRENDED. IT REMAINS TO BE SEEN IF
THE 12Z CMC FOLLOWS SUIT. CONFIDENCE IS AGAIN INCREMENTALLY
INCREASED...BUT REMAIN ABOUT AVERAGE. WILL CONTINUE TO WEIGHT THE
ECMWF/ECENS HEAVIER IN THE BLEND OVERALL AS PREFERENCE...BUT WILL
MIX IN A LITTLE OF THE 12Z GFS TO ACCOUNT FOR THE TREND TOWARD A
STRONGER SURFACE LOW AND TIGHTENING BAROCLINIC ZONE.

...PAIR OF SHORTWAVES FALLING DROPPING ALONG THE WESTERN CANADIAN
COAST TOWARD A MORE AMPLIFIED UPPER LOW OFF THE NORTHWEST COAST BY
SAT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 06Z GEFS/00Z ECMWF
CONFIDENCE: BELOW AVERAGE

MODELS CONTINUE TO SHOW ADDITIONAL SHORTWAVE ENERGY SETTLING SOUTH
OVER TOP OF THE UPPER RIDGE OVER AK...DROPPING DOWN ALONG AND JUST
OFF THE PAC NW COAST FRI/FRI NIGHT. THE SECOND...STRONGER
SHORTWAVE TRACKS ALONG THE BC COAST INTO THE COASTAL WATERS
OFFSHORE WA/OR BY SAT NIGHT. WHILE THE ENSEMBLE SPAGHETTI PLOTS
SHOW INCREASING CONVERGENCE TOWARD A COMMON SOLUTION OVER THE PAST
FEW CYCLES...THERE REMAINS IMPORTANT DETAIL DIFFERENCES.  FOR
EXAMPLE...THE ECMWF IS QUITE AGGRESSIVE IN SHEDDING THE BULK OF
ENERGY WEST TO THE UPPER LOW IN COMPARISON TO 12Z NAM/00Z
CMC/UKMET SHEDDING SOME. THE 12Z GFS SHEDDING NO ENERGY PREFERRING
TO SWING THE SHEARED WAVE INTO THE PACIFIC COAST AND GREAT BASIN
BY FRI/SAT. THIS ALSO LEAVES THE ECMWF HAVING LESS INTERACTION
BETWEEN THE TWO WAVES...AND THEREFORE A BIT CLOSER TO THE COAST
WITH THE SECOND CLOSING OFF WAVE. WILL GO WITH A BLEND OF THE 06Z
GEFS AND THE 00Z ECMWF...WHICH IS A GOOD REPRESENTATION OF THE
CONSENSUS SOLUTION AMONG ENSEMBLE SPAGHETTI HEIGHTS AT THIS TIME.
CONFIDENCE IS SLIGHTLY BELOW AVERAGE AS THERE ARE MANY MOVING
PARTS AND INTERACTIONS THAT ARE KEYED ON TIMING DIFFERENCES...SO
THE PREDICTABILITY IS A BIT TOO LOW TO HAVE TREMENDOUS CONFIDENCE
AT THIS TIME.


www.wpc.ncep.noaa.gov/html/model2.shtml...

www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

MONTEFUSCO

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