Prognostic Meteorological Discussion
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000
FXUS10 KWNH 231847
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
246 PM EDT SAT JUL 23 2016

VALID JUL 23/1200 UTC THRU JUL 27/0000 UTC

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

12Z MODEL EVALUATION INCLUDING PREFERENCE AND FORECAST
CONFIDENCE...

...AMPLIFIED FLOW ACROSS NEW ENGLAND/ASSOCIATED FRONTAL PASSAGE ON
SATURDAY...

PREFERENCE: OPERATIONAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

THE SHORTWAVE TROF WILL DIG ACROSS NEW ENGLAND TODAY WITH A
FRONTAL PASSAGE...THIS IS GENERALLY WELL AGREED UPON PARTICULARLY
TOWARD THE LOWER LEVELS AND TIMING/ORIENTATION.  THERE REMAIN SOME
DEPTH DIFFERENCES WITH THE 12Z NAM AND LESSER SO THE 12Z
GFS...THOUGH IT APPEARS THE NAM DIFFERENCES ARE ASSOCIATED WITH
ITS TYPICAL BIAS OF LINGERING THE STRENGTH/DEPTH OF THE TROF A BIT
LONGER THAN THE REST OF THE GUIDANCE...BUT NO LONGER ENOUGH TO
KEEP IT OUT OF THE PREFERENCE.  AS SUCH AN OPERATIONAL MODEL
PREFERENCE AT ABOVE AVERAGE CONFIDENCE IS SUGGESTED.

19Z UPDATE: LITTLE TO NO CHANGE WAS NOTED WITH THE 12Z
ECMWF/UKMET/CMC AND GEFS TO SUGGEST A CHANGE IN INITIAL THINKING
OF AN OPERATIONAL MODEL BLEND.


...CLOSED UPPER LOW RETROGRADING TOWARD THE FL PENINSULA THROUGH
SUNDAY WITH REDEVELOPMENT/SHIFT WEST TOWARD TEXAS COAST TUES INTO
WED...

PREFERENCE: NON-NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

A UPPER LEVEL TUTT EXISTS JUST EAST OF THE FL PENINSULA AT THIS
TIME WILL CONTINUE TO SHIFT WESTWARD AS THE SUBTROPICAL RIDGE
SHIFTS EASTWARD THROUGH THE EARLY PART OF THE WEEK.   MOST
GUIDANCE WASH OUT THE TUTT BEFORE A REGENERATION OF THE TUTT
OCCURS ACROSS THE WESTERN GULF AND AFFECTS TEXAS BY TUES INTO WED.
 THE 12Z NAM AS TYPICAL...IS DEEPER AND RETAINS THE UPPER LOW
LONGER ACROSS THE CENTRAL GULF A BIT TOO MUCH.  BY TUESDAY THE NAM
IS WEAKER BUT WITH THE GFS/UKMET/CMC AND ECMWF STRENGTHENING THE
PLACEMENT/ORIENTATION ARE BETTER ALIGNED TO BE HELPFUL FOR THE TX
COAST AT THIS POINT IN THE FORECAST CYCLE.  STILL A NON-NAM BLEND
IS PREFERRED AT SLIGHTLY ABOVE AVERAGE CONFIDENCE THROUGH TUES.

19Z UPDATE: LITTLE TO NO CHANGE WAS NOTED WITH THE 12Z
ECMWF/UKMET/CMC AND GEFS TO SUGGEST A CHANGE IN INITIAL THINKING
OF A NON-NAM BLEND.


...SHORTWAVE CROSSING THE US/CANADA BORDER SAT-MON...CLIPPING
MAINE TUES...
...QUICK-MOVING COLD FRONT CROSSING THE NORTHERN TIER STATES...

PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

A FAST MOVING TROF OCCASIONALLY CLOSES OFF AT 5H AS IT TRACKS
ALONG THE US/CANADA BORDER EVENTUALLY SHEARING INTO A DEEPER
CYCLONE OVER HUDSON BAY.  THOUGH THE REMAINING TROF WILL CLIP
NORTHERN MAINE LATE TUESDAY.   THE 12Z GFS CONTINUES TO MATCH VERY
CLOSELY TO EARLIER PREFERENCE INCLUDING THE 00Z ECMWF/ECENS
MEAN...WITH GOOD SUPPORT OF THE 06 GEFS.  THE 12Z NAM BECOMES A
BIT MORE AMPLIFIED...AS IT IS APT TO DO...BY SUN EVENING/MON
MORNING AND IN DOING SO BEGINS TO SIGNIFICANTLY LAG THE GFS/ECMWF
PREFERENCE ACROSS THE UPPER MS VALLEY/GREAT LAKES AND NORTH NEW
ENGLAND.

THE 00Z UKMET/CMC SEEM TO LAG A BIT TOO ON MONDAY; NOT AS
DRAMATICALLY AS THE 12Z NAM.  STILL STRONGER AGREEMENT WITH SOLID
ENSEMBLE SUPPORT CONTINUES TO FAVOR UTILIZING THE GFS/ECMWF BLEND
AT SLIGHTLY ABOVE AVERAGE CONFIDENCE.

19Z UPDATE: THE 12Z UKMET/CMC TRENDED A BIT TIGHTER TO THE 12Z
GFS/00Z ECMWF SOLUTIONS.  THE 12Z ECMWF HOWEVER FAVORED A STRONGER
DEVELOPMENT OF THE LEAD SHORTWAVE/MCS EJECTING OUT OF THE UPPER MS
VALLEY SUN.  THIS STRONGER LEAD WAVE...TRANSLATED TO A
DEEPER/FURTHER EAST SHIFT OF THE MAIN UPPER TROF ACROSS
ONTARIO/QUEBEC AS WELL AS AN EASTWARD SHIFT OF THE SFC CYCLONE AND
FRONTAL PUSH ACROSS NEW ENGLAND.  GIVEN THIS WAS THE OVERALL
PATTERN TREND WILL NOT FULLY DISCOUNT THE NEW ECMWF AND ADD THE
UKMET/CMC TO STABILIZE THE CONTINUITY TOWARD THE GFS.  AS SUCH
WILL FAVOR A NON-NAM BLEND BUT GIVEN THIS SHIFT CONFIDENCE IN THE
BLEND IS REDUCED TO AVERAGE.


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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