Prognostic Meteorological Discussion
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FXUS10 KWNH 281625
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1225 PM EDT WED JUN 28 2017

VALID JUN 28/1200 UTC THRU JUL 02/0000 UTC

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

12Z MODEL EVALUATION WITH PREFERENCES/CONFIDENCE INTERVALS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

KICKER SHORTWAVE HELPING TO EJECT MEAN TROF THROUGH NORTHEAST NEW
ENGLAND TODAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

INNER CORE OF THE OCCLUDED LOW CURRENTLY OVER SE CANADA WILL
SLOWLY DRIFT EAST OVER THE NEXT FEW HOURS BEFORE BEING KICKED BY
COMPACT SHORTWAVE NEAR JAMES BAY LATER TODAY.  THIS KICKER WAVE
WILL ALSO DESCEND AND SHEAR INTO THE LINGERING FILLING TROF OVER
NORTHERN NEW ENGLAND INTO LATE THURSDAY WITH GOOD MODEL AGREEMENT.
AS SUCH WILL SUPPORT A GENERAL MODEL BLEND AT ABOVE AVERAGE
CONFIDENCE FOR THESE FEATURES.


WEAKENING MID-LEVEL TROF CURRENTLY IN WESTERN GULF LIFTING THROUGH
CENTRAL COAST THURS/FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

SURFACE LOW AND BAROCLINIC ZONE ACROSS THE WESTERN GULF WILL
CONTINUE TO LINGER FOR THE NEXT DAY OR SO...WITH SOME UPSCALE
ENHANCEMENT OF WEAK OUT FLOW JET ACROSS THE SOUTHEAST.  MODELS
SHOW GOOD AGREEMENT IN SOME  DAILY CYCLICAL TRENDS AS THE OVERALL
FEATURE SHEARS ENE ACROSS THE CENTRAL GULF THURSDAY FURTHER
WEAKENING THROUGH THE CAROLINAS FRIDAY.  WHILE THE 12Z NAM
CONTINUES TO BE A BIT DEEPER THIS MAY BE DUE TO THE FINER GRID
SCALE AN IMPACT OF UPSCALE INFLUENCES...THOUGH TIMING/PLACEMENT
SEEM QUITE REASONABLE TO KEEP INCLUDED IN ANY BLEND.  THE 00Z CMC
IS ALSO QUITE STRONG BUT ON THIS EVOLUTION IS NOT AS STRUNG
OUT/SHEARED FAVORING TO A SLOWER PROGRESSING CONCENTRATED
SHORTWAVE FEATURE ENOUGH TO CALL IT INTO QUESTION GIVEN OTHER
GUIDANCE.   AS SUCH A NON-CMC BLEND IS SUPPORTED AT SLIGHTLY ABOVE
AVERAGE CONFIDENCE.


SHORTWAVE AND ASSOCIATED SFC LOW CURRENTLY IN UPPER MS VALLEY
MOVING THROUGH N GREAT LAKES INTO DISSIPATING THROUGH N NEW
ENGLAND/SE CANADA FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS AND 00Z ECMWF/UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

GOES-E/RADAR MOSAIC DEPICTS MATURE NEGATIVE TILT MID-LEVEL TROF
WITH NUMEROUS SHORTWAVE SWIRLS ALONG THE INTERFACE IN THE UPPER MS
VALLEY.  THE 12Z GFS HAS FLIPPED BACK TOWARD A DEEPER
REPRESENTATION LIKE THE ECMWF/UKMET THOUGH TYPICAL TO ITS NATURE
IS A BIT EARLIER IN WEAKENING THE WAVE THROUGH SE ONTARIO/SW
QUEBEC BEFORE EVEN REACHING UPPER NEW ENGLAND FRIDAY THOUGH
MOISTURE FLOW/BAROCLINIC ZONE REMAINS ON PAR WITH THE UKMET/ECMWF
TO SUGGEST THIS MAY BE THE BEST DIRECTION OF PREFERENCE.   THE 12Z
NAM SHOWS INITIALLY STRONGER WAVE BUT WEAKENS IT...ADDITIONALLY
UPSTREAM SHORTWAVE IS MUCH DEEPER THAN OTHER GUIDANCE AND AS SUCH
THE WEAKENING SHORTWAVE SLOWS FURTHER DUE TO ITS INFLUENCE.  THIS
SEEMS UNLIKELY.  THE 00Z CMC IS ALSO QUICK TO WEAKEN BUT THE
SHORTWAVE FEATURE AND MOISTURE STREAM SHIFTS EAST TOWARD NORTHERN
NEW ENGLAND MUCH LIKE THE GFS/ECMWF/UKMET...THOUGH THE MASS FIELDS
DO NOT JIVE WELL TO INCORPORATE IN A BLEND THE QPF/MST/ETC PROVIDE
INCREASED CONFIDENCE IN A BLEND OF THE GFS/ECMWF/UKMET AT SLIGHTLY
ABOVE AVERAGE CONFIDENCE.


DEEP-LAYERED LOW MOVING BY THE NORTHERN PLAINS THURS/FRI INTO
GREAT LAKES FRI/SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: AVERAGE

INITIAL CONDITIONS FROM THE PRECEDING WAVE (SEE ABOVE) PLAY
CRITICAL ROLE IN THE EVOLUTION OF THE FRONTAL BOUNDARY AND THE
UPSTREAM SHORTWAVE THAT IS AMPLIFYING ON THE SOUTHEAST PERIPHERY
OF THE CENTER OF THE UPPER LOW OVER S CANADA FRIDAY INTO SAT.  THE
12Z GFS CONTINUES TO TREND TOWARD THE ECMWF OVERALL IN THE MASS
FIELD THOUGH WITH A SLOWER UPSTREAM WAVE SLIGHT INTERACTIONS ON
SAT ACROSS THE GREAT LAKES LEADS TO A CONSOLIDATION OF SURFACE
ENERGY (WEAKENS THE SURFACE REFLECTION ACROSS N MO/N IL.
ENSEMBLES CONTINUE TO SHOW THIS HIGH VARIATION IN THE SURFACE
CLUSTER ANALYSIS...PROVIDING LITTLE CONFIDENCE IN EXACT POSITION
OF THE SURFACE REFLECTION.  HOWEVER...AT LEAST THE FRONTAL
BOUNDARY ORIENTATION/GENERAL PLACEMENT REMAINS FAIRLY STRONG TO
HELP IN QPF/SENSIBLE WX FIELDS A BIT MORE.   THE 00Z CMC IS A
CLEAR OUTLIER HAVING A VERY STRONG RESPONSE ACROSS THE UPPER MS
VALLEY SAT WITH THE UNDERCUTTING SHORTWAVE AND AS SUCH IS NOT
INCLUDED.  THE 00Z UKMET IS ALSO A BIT WEAKER WITH THE UPPER LOW
FAVORING THE SLIGHTLY FASTER UNDERCUTTING SHORTWAVE THROUGH THE
GREAT LAKES AS WELL MAKING IT ALSO STAND OUT WITHIN THE RECENT
ENSEMBLE SUITE.   ALL CONSIDERED A BLEND OF THE 12Z GFS AND 00Z
ECMWF SEEM TO BEST REPRESENT THE ENSEMBLES WHILE SHOWING GOOD
EVOLUTION AGREEMENT WITH TYPICAL DAY 3 TIMING DIFFERENCES (GFS
FAST/ECMWF SLOW).  CONFIDENCE IS AVERAGE GIVEN THE MEDIUM TO
MEDIUM-HIGH SPREAD OF NUMEROUS SMALLER SCALE WAVES AND THEIR
INTERACTION TO THE DEEPER LOW.


SHORTWAVE REACHING NORTHERN PACIFIC COAST LATE FRI SLIDING INTO E
OR/SW ID SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

BY THE END OF THE WEEK A SHORTWAVE ARM OF DEEPER UPPER LOW OVER
GULF OF AK WILL ADVANCE TOWARD THE BC COAST...THIS WILL DRAW SOME
OUT OF THE SUBTROPICS ALONG THE NW EDGE OF THE EASTERN PACIFIC
ANTICYCLONE.  WHILE THE NORTHERN STREAM SHEARS OUT/BREAKS DOWN AT
LANDFALL LIFTING TOWARD BC/VANCOUVER ISLAND THE SOUTHERN STREAM
FEATURE REMAINS FAIRLY ROBUST ENTERING SW OR/CA.  MODELS SHOW
SIMILAR EVOLUTION BUT THE PLACEMENT OF WHERE THE SHORTWAVE
RELATIVE TO THE MEAN JET AXIS WILL DETERMINE THE EVOLUTION ON SAT.
 THE NORTHERN INJECTING SOLUTIONS JUST AS THE UKMET/GFS/ECMWF/NAM
SHOW GREATER N-S SHEARING AFFECTS THOUGH DIRECTING THE WAVE TOWARD
SE OR/ID BY 00Z SUN.  THE CMC IS MUCH TIGHTER TO THE ANTICYCLONE
AND BEING SOUTH ALLOWS FOR INCREASED DEEPENING AND CONSOLIDATION
AND WHILE PLAUSIBLE IT REMAINS ON THE FRINGE OF ENSEMBLE SOLUTIONS
TO SUGGEST A NON-CMC BLEND AS SLIGHTLY ABOVE AVERAGE CONFIDENCE.


WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/

GALLINA

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