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000
FXUS10 KWNH 211720
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
120 PM EDT THU SEP 21 2017

VALID SEP 21/1200 UTC THRU SEP 25/0000 UTC

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

12Z MODEL EVALUATION INCLUDING INITIAL PREFERENCES AND FORECAST
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

...WESTERN CONUS TROUGH AMPLIFICATION AND MOVEMENT THROUGH
SATURDAY...
...SURFACE LOW CYCLOGENESIS AND FRONTAL DEVELOPMENT THROUGH
SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/NAM AND 00Z ECMWF BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

GOOD GENERAL AGREEMENT OF SETTING UP THE TROUGH ACROSS THE WEST
INTO SATURDAY. THE DIFFERENCES COME WHETHER THE TROUGH
PERSISTS/REMAINS CLOSED...OR OPENS AND EJECTS NORTHEAST. THE 12Z
NAM IS THE FARTHEST WEST/STRONGEST WITH THE LOW AFTER TRENDING
WEST FROM THE 00Z RUN. THE 12Z GFS AND 00Z ECMWF ARE SIMILARLY
WEST WHILE THE 00Z CMC AND 00Z UKMET OPEN THE WAVE AND EJECT
NORTHEAST. POSITION OF THIS TROUGH IS PERTINENT TO TROPICAL/GULF
MOISTURE TRANSPORT INTO THE GREAT PLAINS THIS WEEKEND INTO NEXT
WEEK. A BLOCKING PATTERN HAS SET UP AND THEREFORE THE SLOWER/MORE
CLOSED SOLUTIONS ARE PREFERRED AND IN LINE WITH ENSEMBLE TRENDS AT
564 DM AND 570 DM. HENCE A PREFERENCE TO THE 12Z GFS/NAM AND 00Z
ECMWF.


...TROPICAL STORM JOSE...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GUIDANCE CONSENSUS
CONFIDENCE: REFERENCE NHC PRODUCTS

ALL GUIDANCE IN GREAT AGREEMENT OF JOSE WEAKENING AND DRIFTING
BACK WEST TO 70W THROUGH 23/00Z. ONLY SLIGHT VARIATIONS IN THE
GUIDANCE SUITE AS JOSE THEN DRIFTS EAST AS IT FURTHER WEAKENS
THROUGH 25/00Z. CONSENSUS OF MODELS IS CLOSEST TO 15Z NHC
ADVISORY.


...WEAK UPPER LEVEL TROUGH OVER THE SOUTHEAST THROUGH SUNDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL CONSENSUS
CONFIDENCE: ABOVE AVERAGE

THE TROUGH OVER THE SOUTHEASTERN CONUS IS HANDLED SIMILARLY AMONG
THE GUIDANCE. THEREFORE A GENERAL MODEL CONSENSUS IS PREFERRED.


...HURRICANE MARIA...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: REFERENCE NHC PRODUCTS

GOOD AGREEMENT AMONG GUIDANCE COMPARED TO THE 15Z NHC ADVISORY
EXCEPT FOR THE 12Z NAM WHICH REMAINS EAST. NON-NAM BLEND IS
CLOSEST TO NHC 15Z ADVISORY.

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

JACKSON

$$





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