Prognostic Meteorological Discussion
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000
FXUS10 KWNH 200537
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
137 AM EDT SUN AUG 20 2017

VALID AUG 20/0000 UTC THRU AUG 23/1200 UTC

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

...AN EVALUATION OF THE 00Z NAM/GFS ALONG WITH PRELIMINARY
PREFERENCES/FORECAST CONFIDENCE...

...QUASI-STATIONARY UPPER LOW SPINNING IN THE VICINITY OF CA
THROUGH TUESDAY...

PREFERENCE: NON-12Z CANADIAN COMPROMISE
FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE NAM HAS TRENDED A LITTLE FURTHER EAST FROM ITS PREVIOUS
RUN...PLACING IT INTO BETTER AGREEMENT WITH THE GREATER MODEL
CONSENSUS.  DIFFERENCES ARE NOT TREMENDOUS THROUGHOUT THE
FORECAST...ALTHOUGH THE 12Z CANADIAN DOES DRIFT TO THE EASTERN
EDGE OF THE SOLUTION ENVELOPE ON WED.

...VIGOROUS IMPULSE LIFTING OUT OF NORTH-CENTRAL MX INTO THE FOUR
CORNERS REGION BY 20/1200Z...

PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: AVERAGE

OVERALL MODELS ARE IN GENERALLY GOOD AGREEMENT WITH THIS FEATURE
AS IT LIFTS NORTH ACROSS AZ/NM ON SUN AND THEN NORTHEAST INTO THE
CENTRAL HIGH PLAINS ON MON...BEFORE BECOMING CAPTURED THE
AMPLIFYING TROUGH OVER THE CENTRAL PLAINS BY MON EVENING.

...BAND OF MID-LEVEL HEIGHT FALLS TRACKING FROM THE LOWER GREAT
LAKES/MID ATLANTIC THROUGH NEW ENGLAND...

PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: ABOVE AVERAGE

OVERALL MODELS ARE IN GOOD AGREEMENT THROUGH SUN EVENING AS THE
TROUGH LIFTS FROM NEW ENGLAND INTO THE CANADIAN MARITIMES.


...TRAILING LONGWAVE TROUGH EXTENDING ALONG THE NORTH-CENTRAL U.S.
EARLY NEXT WEEK...
...ASSOCIATED FRONTAL ZONE SWEEPING THROUGH THE CENTER OF THE
COUNTRY...

PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE

OVERALL THE MODELS ARE IN GOOD AGREEMENT WITH THE TROUGH
AMPLIFYING OVER THE UPPER MIDWEST/GREAT LAKES AND THE ASSOCIATED
SURFACE CYCLONE LIFTING NORTHEASTWARD ACROSS THE UPPER GREAT LAKES
ON TUE.  THE NAM IS MORE AMPLIFIED ALOFT THAN ITS 12Z RUN AND
FURTHER WEST WITH ITS LOW TRACK...PLACING IT INTO BETTER AGREEMENT
WITH THE GENERAL MODEL CONSENSUS.  WHILE THE TIMING OF THE
TRAILING FRONT IS SIMILAR TO THE OTHER MODELS ACROSS THE GREAT
LAKES/OH VALLEY INTO THE NORTHEAST...THE GFS MOVES TO THE EASTERN
EDGE OF THE GUIDANCE WITH THE LOW TRACK ACROSS SOUTHERN QUEBEC ON
WED.

...TUTT CELL DRIFTING WESTWARD ACROSS THE GULF OF MX THROUGHOUT
THE PERIOD...

FINAL PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: AVERAGE

MODELS REMAIN IN GENERALLY GOOD AGREEMENT SHOWING THIS SYSTEM
MOVING ACROSS FL AND THE NORTHERN GULF...REACHING THE WESTERN GULF
COAST REGION BY LATE TUE.

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

PEREIRA


$$




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