Prognostic Meteorological Discussion
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526
FXUS10 KWNH 290651
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 AM EDT FRI JUL 29 2016

VALID JUL 29/0000 UTC THRU AUG 01/1200 UTC

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

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

TUTT ENERGY LIFTING INTO MID-ATLANTIC/NEW ENGLAND FRI INTO SAT
WITH SURFACE LOW DEVELOPING IN VA PIEDMONT AND MOVING ALONG
NORTHEAST COAST THROUGH SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

SYNOPTIC SPREAD REMAINS FAIRLY SMALL WITH RESPECT TO THE REMAINING
SHORTWAVE ENERGY OF THE OLD TUTT TRANSLATING ACROSS THE
MID-ATLANTIC INTO NEW ENGLAND BY FRI EVENING.  SOME SPREAD REMAINS
WITH RESPECT TO THE SURFACE LOW ALONG THE FRONTAL BOUNDARY BUT
GIVEN IT IS GENERALLY WEAK...THIS WOULD BE EXPECTED GIVEN THE
FIELD`S RESPONSE TO MESOSCALE CONVECTION...PLEASE REFER TO WPC
QPFPFD FOR ADDITIONAL DETAILS ON THE QPF/QPF AXIS.  THE 12Z CMC IS
THE ONLY SIGNIFICANT OUTLIER BEING FAST (ATYPICAL OF THE CMC) AND
DEEP (TYPICAL) MAINLY AT THE SURFACE; ESPECIALLY COMPARED TO
GEFS/ECENS MEANS.  A NON-CMC BLEND IS PREFERRED AT ABOVE AVERAGE
CONFIDENCE.

07Z UPDATE: THE 00Z CMC HAS SHIFTED A BIT SLOWER AND THOUGH
REMAINS A BIT FAST THAN THE CLUSTER AFTER 30/12Z...AN OVERALL
MODEL BLEND IS SUPPORTED AT ABOVE AVERAGE CONFIDENCE.


MULTIPLE WEAK SHORTWAVES OVERTOPPING SW RIDGE TO CARVE OUT A
BROAD/WEAK TROF ACROSS LOWER MISSOURI RIVER VALLEY FRI AND INTO
THE SOUTHERN GREAT LAKES/OH RIVER VALLEY BY SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND UNTIL 01/00Z...NON-CMC
AFTERWARD
CONFIDENCE: SLIGHTLY AVERAGE AVERAGE

BROAD TROUGHING EXISTS AND WILL CONTINUE TO DEVELOP ACROSS THE
NORTHERN PLAINS INTO THE MS RIVER VALLEY IN THE WAKE OF THE
EXITING CLOSED LOW IN CANADA/TUTT CELL LIFTING NORTHEAST THROUGH
NEW ENGLAND.  THIS PATTERN SUPPORTS NUMEROUS CONVECTIVELY INDUCED
UPSCALE GROWTH SCENARIOS...SOME WITH ADDITIVE EFFECTS...AS WAVES
DROP SOUTHEAST AROUND THE PERIPHERY OF THE SOUTHWESTERN U.S.
RIDGE.  THE 12Z CMC AND UKMET BOTH SUPPORT THIS ADDITIVE EFFECT
ACROSS THE LOWER OHIO VALLEY INTO LOWER GREAT LAKES BY SAT; THE
UKMET LESSER SO.  CONTRARY TO THIS THE 12Z ECMWF AND 00Z NAM/GFS
CONTINUE TO BE ALIGNED QUITE WELL WITH THE TIMING OF THE ENSEMBLE.
 THOUGH VARIATION IN QPF CAN BE QUITE SUBSTANTIAL...PLEASE REFER
TO QPFPFD FOR ADDITIONAL DETAILS.  OTHERWISE WILL CONTINUE TO
SUPPORT A 00Z GFS/NAM AND 12Z ECMWF BLEND AS MOST PROBABLE OUTCOME
AT THIS TIME.

07Z UPDATE: WHILE THE 00Z UKMET AND CMC CONTINUE TO BE ON THE
STRONGER SIDE OF THE GUIDANCE IN CONSOLIDATING THE VORT CENTER IN
THE LOWER GREAT LAKES BY SUN BOTH ARE IN BETTER SUPPORT OF EARLIER
00Z GFS/NAM AND ECMWF PREFERENCE.  AT THIS POINT THE 00Z CMC
SUPPORTS A DEEPER/FURTHER SOUTH 7H AND SFC CENTER ACROSS THE
CENTRAL APPALACHIANS/MID-ATLANTIC ON MON.  AN OPERATIONAL MODEL
BLEND THROUGH 01/00Z AND NON-CMC AFTERWARD IS SUPPORTED AT
SLIGHTLY ABOVE AVERAGE CONFIDENCE.


LEAD SHORTWAVE TROF CLOSING OFF WHILE CROSSING SW CANADA BY SAT
INTO MON
SECOND CLOSED LOW APPROACHING THE PAC NORTHWEST BY MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~
PREFERENCE: OPERATIONAL MODEL BLEND
CONFIDENCE: AVERAGE

A DEVOLVING CLOSED LOW IN THE GULF OF ALASKA IS ELONGATING WITH
NUMEROUS INTERNAL SHORTWAVES NOTED.  AS THE OVERALL PATTERN
SUPPORTS SOUTHEASTWARD TRACKING OF THE ENERGY...THE MODELS ARE IN
GENERAL AGREEMENT WITH THE EVENTUAL INTERACTION OF SHORTER WAVE
FEATURES CONSOLIDATING INTO TWO MORE CONCENTRIC CLOSED LOW(S)
ACROSS WESTERN CANADA AND THE GULF OF ALASKA OVER THE WEEKEND INTO
MON.   THE LEAD WAVE HAS STRONGER MODEL AGREEMENT BUT THERE
REMAINS SOME SPREAD PARTICULARLY WITH THE OVERALL STRENGTH.  THE
00Z NAM (ALONG WITH THE 12Z UKMET) HAS SHIFTED TO A MUCH DEEPER
CONCENTRIC SOLUTION BUT ALSO A NORTHERN SOLUTION WITH THE
CENTER/TRACK.  THE GFS HAS BEEN VERY SOLID AND CONSISTENT OVER THE
PAST DAY OR SO WITH THE EVOLUTION OF THIS LOW THOUGH ALSO ON THE
WEAKER/SHALLOWER SIDE IS MORE CENTRAL TO THE OVERALL CLUSTER AND
CONTINUES TO BE MOST FAVORED.  THE ECMWF HAS BEEN LESS RELIABLE
THOUGH APPEARS TO BE CONSOLIDATING ON A SOLUTION...THOUGH THE 12Z
RUN (SUPPORTED BY THE 12Z ECENS MEAN) REMAINS THE SOUTHERN-MOST ON
THE TRACK OF THE LOW.   THE 12Z CMC IS MOST OF AN OUTLIER AS IT
REMAINS QUITE ELONGATED/ECCENTRIC COMPARED TO THE OTHER CONCENTRIC
DETERMINISTIC MODELS.  OVERALL WILL CONTINUE TO FAVOR A NON-CMC
BLEND AT SLIGHTLY ABOVE AVERAGE CONFIDENCE.

THE UPSTREAM SECOND CLOSED LOW APPROACHES VANCOUVER ISLAND/NW
WASHINGTON BY THE END OF THE FORECAST PERIOD... MODELS ARE MUCH
TIGHTER PACKED ON THE EVOLUTION EXCEPT THE CMC WHICH IS
WEAKER/SLOWER.  THE 12Z UKMET IS A BIT FAST...PER USUAL BUT NOT
ENOUGH TO BREAK FROM THE NON-CMC BLEND FOR BOTH SYSTEMS.

07Z UPDATE: FOR THE LEAD LOW IN SW CANADA SUN/MON: THE 00Z CMC
SHIFTED INTO BETTER SUPPORT OF THE 00Z GFS AS WELL AS THE ECMWF
THOUGH IT DOES REMAIN THE SOUTHERN SOLUTION TO THE GUIDANCE.  THE
UKMET WHICH HAD SUPPORTED INCLUSION OF NAM BEING A BIT STRONGER
AND NORTH...THE 00Z UKMET BACKED OFF AND THOUGH STILL NORTH IS
WEAKER AND MORE IN LINE WITH THE 00Z GEFS; JUST A BIT NORTH OF THE
00Z GFS.  THIS MAKES THE NAM AN OUTLIER IN BOTH LATITUDE/TRACK AS
WELL AS INTENSITY WITH THIS LEAD WAVE...THOUGH THE NAM IS VERY
SOLID WITH THE SECOND WAVE APPROACHING WA BY MON.  HOWEVER...THE
UKMET IS NOW SLOWER AND MORE ELONGATED WITH THE SECOND
WAVE...OTHERWISE THE 00Z ECMWF/CMC ARE ALSO WELL CLUSTERED HERE
TOO.  ALL CONSIDERED A NON-NAM FOR THE LEAD WAVE AND A NON-UKMET
BLEND FOR THE SECOND MAY BE BEST SOLUTION IF CAPABLE; OTHERWISE
THE SPREAD AND MODEL DIFFERENCES ARE SMALL ENOUGH TO SUPPORT AN
OPERATIONAL MODEL BLEND THOUGH AT SLIGHTLY LOWER CONFIDENCE
(AVERAGE) GIVEN THE BROADER SOLUTION THAT EXISTS AFTER BLENDING


GALLINA

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

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

$$





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