Prognostic Meteorological Discussion
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000
FXUS10 KWNH 190703
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
302 AM EDT TUE SEP 19 2017

VALID SEP 19/0000 UTC THRU SEP 22/1200 UTC

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

00Z MODEL EVALUATION...WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...INITIAL CLOSED LOW APPROACHING THE PACIFIC NORTHWEST...
...UPPER TROUGH SWEEPING ACROSS THE NORTHWEST THROUGH TUES...
...ASSOCIATED COLD FRONT EJECTING OUT INTO THE PLAINS TUES-WED...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS CONSENSUS
CONFIDENCE: AVERAGE

THE MODEL DIFFERENCES WITH THE NEXT SURGE OF HEIGHT
FALLS/TROUGHING DROPPING DOWN ACROSS THE NORTHWEST ARE NOT AS
SIGNIFICANT AS 24 HOURS AGO...BUT THE 00Z GFS CONTINUES TO SUPPORT
A STRONGER CLOSED LOW EVOLUTION OVER SOUTHERN CANADA AS THE
INITIAL SURGE OF HEIGHT FALLS PIVOT ACROSS THE NORTHERN ROCKIES
AND THE NORTHERN PLAINS BEFORE LIFTING UP THROUGH SASKATCHEWAN AND
MANITOBA. THE TIMING DIFFERENCES ASSOCIATED WITH THE COLD FRONT
EJECTING OUT ACROSS THE PLANS ARE RATHER MODEST AT THIS TIME AT
LEAST THROUGH WED. SINCE THE GFS APPEARS TO BE STILL A BIT MORE
OUT OF TOLERANCE THROUGH THIS PERIOD COMPARED TO THE OTHER MODELS
WHICH ARE BETTER CLUSTERED...IT HAS BEEN DECIDED TO LEAN TOWARD A
NON-GFS CONSENSUS AT THIS TIME.


...NEW CLOSED LOW/ENERGY REACHING THE PACIFIC NORTHWEST BY WED...
...SURFACE LOW ADVANCING INTO WESTERN WA TUES NIGHT/WED...
...DEEP TROUGH/CLOSED LOW  EVOLUTION OVER THE WEST BY THURS...
...SURFACE WAVE DEVELOPMENT OVER THE PLAINS BY FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC CONSENSUS
CONFIDENCE: AVERAGE

THE MODELS AGREE IN BRINGING ANOTHER SURGE OF STRONG HEIGHT FALLS
INTO THE NORTHWEST BY WED AS A SURFACE LOW MOVES INTO WESTERN WA.
THIS WILL LEAD TO A LARGER SCALE DEEP TROUGH AND CLOSED LOW OVER
THE WEST BY THURS. BY FRI...THE HEIGHT FALLS WILL BE ENCROACHING
ON THE HIGH PLAINS AND WILL ALLOW A WAVE OF LOW PRESSURE TO
DEVELOP ALONG THE AFOREMENTIONED COLD FRONT THAT EJECTS OUT ACROSS
THE CENTRAL/NORTHERN PLAINS WITH THE INITIAL SURGE OF SHORTWAVE
ENERGY/TROUGHING. THERE IS BETTER AGREEMENT TONIGHT WITH THE DEPTH
OF THE RENEWED TROUGH AND ITS PLACEMENT...AND ALL OF THE MODELS
AGREE THAT THERE WILL BE A SOMEWHAT ELONGATED UPPER LOW OVER THE
INTERMOUNTAIN WEST BY EARLY FRI. ALTHOUGH THE 00Z CMC DOES APPEAR
TO BE A TAD TOO DEEP. MOST OF THE MASS FIELD DIFFERENCES ACTUALLY
TEND TO BE MORE RELATED TO THE SURFACE FRONT BY THE END OF THE
PERIOD AND PLACEMENT OF THE SURFACE WAVE OVER THE PLAINS. THE 00Z
ECMWF IS SOMEWHAT SLOWER WITH THE FRONT AND FARTHER NORTH WITH THE
LOW CENTER...WITH THE 00Z GFS FARTHER EAST WITH THE FRONT AND LOW
CENTER. THE 00Z NAM AND 00Z UKMET SPLIT THE DIFFERENCE. THE 00Z
CMC MEANWHILE IS GENERALLY THE MOST SUPPRESSED WITH THE FRONT AND
IS WELL SOUTHWEST WITH ITS LOW CENTER COMPARED TO THE MODEL
CONSENSUS. SINCE THE CMC APPEARS TO BE THE OVERALL OUTLIER...A
NON-CMC CONSENSUS WILL BE PREFERRED FOR THE TIME BEING.


...HURRICANE JOSE...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC CONSENSUS OVERALL IS CLOSEST TO THE NHC TRACK
CONFIDENCE: REFERENCE NHC PRODUCTS

EARLY IN THE PERIOD...THE LATEST (03Z) NHC TRACK OF HURRICANE JOSE
IS CLOSE TO THE GLOBAL MODEL CONSENSUS...ALTHOUGH THE 12Z ECMWF IS
A TAD LEFT OF THE NHC TRACK THROUGH THE FIRST 36 HOURS. AFTER 48
HOURS...THE 12Z CMC BECOMES FASTER THAN THE NHC TRACK AND IS
FARTHER TO THE NORTHEAST WITH JOSE. THE 00Z NAM IS ALSO A BIT
NORTH OF THE NHC TRACK. A NON-CMC CONSENSUS BETTER REPRESENTS THE
NHC TRACK IN THE LATTER PERIODS AS JOSE SLOWS DOWN AND BEGINS TO
POSSIBLY INITIATE A CLOCKWISE LOOP WELL SOUTHEAST OF NEW ENGLAND
BY 84 HOURS.


...BROAD UPPER TROUGH OVER THE SOUTHEAST AND GULF COAST REGION...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

THE MODELS ALLOW FOR A BROAD AND WEAK UPPER TROUGH TO BE LEFT
BEHIND OVER THE SOUTHEAST AND THE GULF COAST STATES IN THE WAKE OF
HURRICANE JOSE TRACKING NORTH UP OFF THE EAST COAST. THE MODELS
ARE IN GOOD AGREEMENT WITH THE BROADER DETAILS OF THE TROUGH...SO
A GENERAL MODEL BLEND WILL BE PREFERRED.


www.wpc.ncep.noaa.gov/html/model2.shtml
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml

ORRISON

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