Prognostic Meteorological Discussion
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086
FXUS10 KWNH 190506
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1205 AM EST SUN FEB 19 2017

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

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

00Z MODEL EVALUATION...INCLUDING THE NAM AND GFS


...SHORTWAVE/COLD FRONT CROSSING THE NORTHEAST THROUGH SUN...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS SHOW SIMILARLY WITH THIS SYSTEM.


...DEEPENING TROUGH/CLOSED LOW DEVELOPMENT NEAR NORTHERN NEW
ENGLAND/NOVA SCOTIA...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

IN THE WAKE OF THE SHORTWAVE CROSSING THE NORTHEAST DURING THE DAY
SUN...THE MODELS ADVERTISE AN AMPLIFYING TROUGH NEAR NORTHERN NEW
ENGLAND BY SUN NIGHT...WITH A CLOSED LOW DEVELOPING OVER THE NOVA
SCOTIA ON MON. THE MODELS ARE IN GOOD AGREEMENT THIS AND SO A
GENERAL MODEL COMPROMISE WILL BE PREFERRED.


...SHORTWAVE/SURFACE LOW APPROACHING THE PACIFIC NORTHWEST ON
SUN...
...UPPER TROUGH EJECTING OUT OF THE SOUTHWEST THROUGH SUN...
...CONSOLIDATING ENERGY EJECTING OUT ACROSS THE PLAINS/MIDWEST...
...SURFACE LOW PRESSURE/COLD FRONT CROSSING THE PLAINS/MIDWEST...

PREFERENCE: BLEND OF THE 00Z GFS AND 12Z UKMET
CONFIDENCE: AVERAGE...BECOMING BELOW AVERAGE

A NORTHERN STREAM TROUGH AND ASSOCIATED SURFACE LOW WILL APPROACH
THE PACIFIC NORTHWEST ON SUN...WITH THE ENERGY THEN QUICKLY
TRAVERSING THE NORTHERN ROCKIES AND NORTHERN PLAINS THROUGH MON.
THIS ENERGY WILL BE RESULTING IN LEE-SIDE CYCLOGENESIS ACROSS THE
HIGH PLAINS BY LATER SUN. MEANWHILE...THESE HEIGHT FALLS WILL HELP
TO KICK A PORTION OF THE SOUTHERN STREAM TROUGH/CLOSED LOW OUT OF
THE SOUTHWEST AND NORTHEASTWARD ACROSS THE CENTRAL PLAINS AND THE
MIDWEST THROUGH MON AND TUES. SOME PARTIAL PHASING WILL ALLOW
DEEPENING LOW PRESSURE UP ACROSS THE NORTHERN PLAINS...WITH A
TRAILING COLD FRONT EXTENDING SOUTH ACROSS THE CENTRAL PLAINS. ALL
OF THIS ENERGY QUICKLY MOVES NORTHEAST ACROSS THE MIDWEST AND
GREAT LAKES THROUGH TUES. THE 12Z CMC IS A PROGRESSIVE OUTLIER
SOLUTION WITH THE NORTHERN STREAM ENERGY COMPARED TO AN OTHERWISE
WELL-CLUSTERED MODEL SUITE. HOWEVER...WITH THE SOUTHERN STREAM
ENERGY EJECTING OUT...THE 00Z GFS AND 12Z UKMET BECOME THE MOST
PROGRESSIVE SOLUTIONS...WITH THE 00Z NAM/12Z CMC AND 12Z ECMWF ALL
A BIT SLOWER. THE GFS DID TREND A BIT MORE PROGRESSIVE IN EJECTING
THIS ENERGY NORTHEASTWARD. THERE IS GOOD MODEL CLUSTERING WITH THE
SURFACE LOW PRESSURE EVOLUTION BETWEEN THE 00Z GFS/12Z UKMET AND
12Z ECMWF...BUT THEN THE DIFFERENCES BECOME FOCUSED ON THE COLD
FRONT IN WHICH THE ECMWF LAGS THE GFS/UKMET WITH TIME. THE NAM AND
CMC ARE SLOW WITH THE FRONT LIKE THE ECMWF AS IT CROSSES THE
MIDWEST THROUGH TUES. CONFIDENCE BECOMES LIMITED IN TIME...BUT
WILL LEAN TOWARD A BLEND OF THE GFS AND UKMET AT THIS TIME
ACCOMMODATING THE LATEST TRENDS AND OVERLAPPING AGREEMENT WITH
NORTHERN AND SOUTHERN STREAM ENERGY. MUCH OF THE UNCERTAINTY AGAIN
IS CENTERED ON THE FRONTAL TIMING ACROSS THE MIDWEST.


...UPPER TROUGH TRACKING ACROSS THE SOUTHEAST ON SUN...

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

ONLY MINOR DIFFERENCES REMAIN AT THIS POINT WITH THE SYSTEM. A
GENERAL MODEL COMPROMISE CAN BE USED HERE.


...SHORTWAVE/SURFACE LOW APPROACHING THE WEST COAST ON MON...

PREFERENCE: BLEND OF THE 12Z UKMET AND 12Z ECMWF
CONFIDENCE: SLIGHTLY BELOW AVERAGE

AS A BROADER UPPER TROUGH EVOLVES OFF THE WEST COAST...THE
GUIDANCE SHOWS THE NEXT IN A SERIES OF SHORTWAVE IMPULSES AND
ACCOMPANIES SURFACE LOWS APPROACHING THE WEST COAST BY EARLY MON.
THE 00Z NAM IS A BIT SLOW WITH THIS IMPULSE BUT ALSO FAIRLY
SHEARED WHICH RESULTS IN A WEAKER SURFACE REFLECTION COMPARED TO
THE MODEL CONSENSUS. THE 12Z CMC IS BY FAR THE MOST PROGRESSIVE
SOLUTION. THE 00Z GFS AGAIN IS THE STRONGEST SOLUTION AND IS THE
MOST INTENSE WITH ITS SURFACE LOW. MEANWHILE...THE 12Z UKMET AND
12Z ECMWF ARE CLUSTERED TOGETHER ON A SOMEWHAT FLATTER SOLUTION
RELATIVE TO THE GFS...WITH A WAVE TRACK A TAD SOUTH OF THE
UKMET/ECMWF CAMP. WILL FAVOR THE UKMET/ECMWF CAMP WHICH HAS ALSO
BEEN RATHER CONSISTENT WITH THIS IMPULSE.


...SHORTWAVE/SURFACE LOW APPROACHING THE WEST COAST MON NIGHT...

PREFERENCE: BLEND OF THE 12Z UKMET AND 12Z ECMWF
CONFIDENCE: SLIGHTLY BELOW AVERAGE

YET ANOTHER SHORTWAVE AND ASSOCIATED SURFACE LOW WILL APPROACH THE
WEST COAST MON NIGHT ALONG WITH A COLD FRONT THAT WILL MOVE
INLAND. THE 00Z GFS IS THE MOST PROGRESSIVE WITH THIS
SYSTEM...WITH THE 12Z CMC THE SLOWEST AND DEEPEST. THE 00Z
NAM...12Z UKMET AND 12Z ECMWF ARE IN BETWEEN SOLUTIONS...BUT THERE
IS BETTER AGREEMENT WITH THE UKMET AND ECMWF...AND SINCE THEY ARE
CLOSE TO THE MODEL CONSENSUS...A UKMET/ECMWF BLEND WILL BE
PREFERRED.


...LONGWAVE TROUGH FINALLY REACHING THE WEST COAST BY WED...

PREFERENCE: BLEND OF THE 00Z GFS AND 12Z ECMWF
CONFIDENCE: SLIGHTLY BELOW AVERAGE

THE LONGWAVE TROUGH EVOLVING OFF THE WEST COAST FINALLY BEGINS TO
MOVE ASHORE BY WED ALONG THE WEST COAST. BY THAT TIME...THERE IS
GENERALLY BETTER AGREEMENT/CLUSTERING WITH THE 00Z GFS AND 12Z
ECMWF. THE 12Z UKMET APPEARS TOO STRONG/SLOW WITH ITS NEXT SURFACE
LOW...AND THE 00Z NAM/12Z AND 12Z UKMET ALL SEEM TO HAVE POSSIBLY
A LITTLE TOO MUCH ENERGY DIGGING IN THE BASE OF THE TROUGH.


...SOUTHERN STREAM TROUGH/CLOSED LOW DEVELOPMENT NEAR THE WESTERN
GULF COAST...

PREFERENCE: BLEND OF THE 00Z GFS/18Z GEFS MEAN AND THE 12Z ECENS
MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE

ENERGY IN THE BASE OF THE UPPER TROUGH/CLOSED LOW CURRENTLY
IMPACTING THE SOUTHWEST THAT EJECTS OUT ACROSS THE PLAINS THROUGH
SUN AND MON WILL SEPARATE OUT AND LEAD TO A NEW SOUTHERN STREAM
TROUGH AND POSSIBLE CLOSED LOW OVER EASTERN TX AND THE ADJACENT
LOWER MS VALLEY BY TUES. DIFFERENCES IN THE EVOLUTION OF THIS
TROUGH ARE DEPENDENT ON HOW THE ENERGY NORTH ACROSS THE MIDWEST
EVOLVES...DESCRIBED ABOVE WITH LOWER THAN AVERAGE CONFIDENCE. THE
12Z ECMWF IS THE STRONGEST SOLUTION WITH THE CLOSED LOW
DEVELOPMENT...WITH THE 12Z CMC THE WEAKEST. THE 00Z GFS IS VERY
CLOSE TO THE 12Z ECMWF...EXCEPT IS A BIT WEAKER. THE 12Z UKMET
TENDS TO DIG MORE ENERGY A BIT FARTHER SOUTH AND IS A BIT SLOWER
IN TIME VERSUS THE GFS AND ECMWF. THE LATEST GEFS MEAN AND ECENS
MEAN ARE WELL CLUSTERED AND BOTH TEND TO FAVOR THE GFS MORE SO
THAN THE ECMWF. WILL LEAN TOWARD A CONSENSUS OF THE GFS/GEFS MEAN
AND ECENS MEAN AT THIS TIME.


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

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

ORRISON

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