Prognostic Meteorological Discussion
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000
FXUS10 KWNH 250730
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
329 AM EDT TUE JUL 25 2017

VALID JUL 25/0000 UTC THRU JUL 28/1200 UTC

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

00Z MODEL EVALUATION WITH FINAL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


...SHORTWAVE EXITING THE NORTHEAST TODAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

THE 00Z CMC ADJUSTED IN LINE WITH THE REMAINING DETERMINISTIC
GUIDANCE REGARDING A WEAK SURFACE LOW EAST OF THE NRN MID-ATLANTIC
COAST TODAY. ANY REMAINING MODEL DIFFERENCES ARE SMALL ENOUGH TO
SUPPORT A GENERAL MODEL BLEND WITH THIS SYSTEM.


...MID-LEVEL TROUGHING ACROSS THE GULF COAST SHIFTING TOWARD GA/SC
WED/THURS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS...00Z ECMWF...00Z CMC BLEND
CONFIDENCE: AVERAGE

THE 00Z NAM/GFS/ECMWF AND THE LATEST ENSEMBLE MEANS SUPPORT MORE
IN THE WAY OF AN ELONGATED LOW TO MID-LEVEL TROUGH AXIS ACROSS THE
SOUTHEAST STARTING WED...BUT THE 00Z UKMET/CMC ARE MORE DEVELOPED
WITH A CLOSED LOW IN THE VICINITY OF THE COAST. ENSEMBLE SPAGHETTI
PLOTS SHOW WEAK SUPPORT FOR THE UKMET/CMC IDEA...BUT WITH THE 00Z
UKMET SLOWEST/FARTHEST WEST...AND THE 00Z NAM MOST
PROGRESSIVE/FLATTEST...WILL GO WITH A BLEND TOWARD THE MIDDLE.
THIS IS BEST SHOWN BY THE 00Z GFS/ECMWF/CMC.


...SYSTEM MOVING THROUGH SOUTHERN CANADA THROUGH WEDNESDAY
UNFOLDING TO ENCOMPASS THE GREAT LAKES BY THURS WITH ACCOMPANYING
SURFACE LOW FORECAST TO INTO THE UPPER MIDWEST BY THU MORNING...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/ECMWF/UKMET BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE

CONFIDENCE REMAINS FAIRLY LOW WITH THIS SYSTEM GIVEN UNCERTAINTY
IN CONVECTIVE EVOLUTION. THE BIGGEST DIFFERENCES ARE ACROSS THE
MIDWEST WITH A SURFACE LOW STARTING WED NIGHT. THE MODELS ALL SEEM
TO SHOW SOME DEGREE OF FEEDBACK...BUT THE 00Z NAM IS TOWARD THE
DEEPER SIDE OF THE AVAILABLE GUIDANCE REGARDING A MID-LEVEL
VORTICITY IN THE BASE OF A BROAD TROUGH ACROSS THE GREAT LAKES
REGION. THE 00Z ECMWF TRENDED TOWARD THE MORE 00Z UKMET/GFS IDEA
WHICH FITS INTO THE WIDE VARYING ENSEMBLE SPREAD. GIVEN
UNCERTAINTY...WOULD PREFER TO STAY IN THE MIDDLE...WITH GREATER
SUPPORT...NEARER TO A BLEND OF THE 00Z GFS/ECMWF/UKMET.


...CLOSED UPPER LOW NEAR CALIFORNIA THROUGH WED BEFORE LIFTING
NORTHEAST TOWARD ID THURS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

THE 00Z MODELS SHOW SIMILARLY WITH THIS SYSTEM.


...MID-LEVEL WAVE DEVELOPING TO GLOBAL TROF OVER EASTERN GULF OF
AK WITH AN EMBEDDED KICKER SHORTWAVE NEARING PACIFIC NORTHWEST BY
EARLY THURS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE

THE 00Z MODELS SHOW SIMILARLY WITH THIS SYSTEM.


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

OTTO

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