Prognostic Meteorological Discussion
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000
FXUS10 KWNH 190639
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
138 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/GFS/UKMET/CMC AND ECMWF


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

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE MODELS ARE VERY SIMILAR 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...
...ELONGATED ENERGY EJECTING OUT ACROSS THE PLAINS/MIDWEST...
...SURFACE LOW PRESSURE/COLD FRONT CROSSING THE PLAINS/MIDWEST...

PREFERENCE: BLEND OF THE 00Z GFS AND 00Z 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. THIS WILL RESULT IN AN ELONGATED
TROUGH AXIS EJECTING ACROSS THE PLAINS WITH SOME PARTIAL PHASING
WHICH 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 00Z CMC IS STILL A
SOMEWHAT WEAKER/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 00Z UKMET BECOME THE MOST PROGRESSIVE SOLUTIONS...WITH THE
00Z NAM/00Z CMC AND 00Z 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/00Z UKMET AND 00Z 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 00Z UKMET AND 00Z ECMWF
CONFIDENCE: 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 00Z CMC IS STILL THE MOST PROGRESSIVE
SOLUTION AND IS WEAKER. THE 00Z GFS AGAIN IS THE STRONGEST
SOLUTION AND IS THE MOST INTENSE WITH ITS SURFACE LOW.
MEANWHILE...THE 00Z UKMET AND 00Z 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: NON-GFS CONSENSUS
CONFIDENCE: 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 REMAINING MODELS ACTUALLY NOW CLUSTERING A BIT
BETTER ON A SOLUTION A LITTLE SLOWER. WILL FAVOR A NON-GFS
CONSENSUS AT THIS TIME WITH THIS PARTICULAR SYSTEM.


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

PREFERENCE: BLEND OF THE 00Z GFS AND 00Z ECMWF
CONFIDENCE: 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 00Z
ECMWF. THE 00Z UKMET APPEARS TOO STRONG/SLOW WITH ITS NEXT SURFACE
LOW...AND THE 00Z NAM/00Z CMC AND 00Z UKMET ALL SEEM TO HAVE A BIT
TOO MUCH ENERGY DIGGING IN THE BASE OF THE TROUGH. WILL FAVOR THE
CLUSTERING OF THE GFS AND ECMWF AT THIS TIME.


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

PREFERENCE: BLEND OF THE 00Z GFS/00Z UKMET AND 12Z ECMWF
CONFIDENCE: 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. THE 00Z UKMET AND 12Z/00Z ECMWF ARE NOW THE STRONGEST
SOLUTIONS WITH THE CLOSED LOW EVOLUTION AND ESPECIALLY AS THE
ENERGY EJECTS OUT INTO THE GULF OF MEXICO TUES AND WED. THE 00Z
ECMWF THOUGH IS MORE PROGRESSIVE THAN ITS PREVIOUS RUN. THE 00Z
GFS IS VERY CLOSE TO THE 00Z UKMET/12Z ECMWF CAMP...EXCEPT IT IS A
BIT WEAKER. THE 00Z CMC REMAINS A WEAK OUTLIER. THERE REMAINS
SPREAD WITH TIMING AND DEPTH OF THE CLOSED LOW...BUT BASED ON
OVERALL CLUSTERING AND HEDGING ON STRENGTH...WILL RECOMMEND A
COMPROMISE OF THE RELATIVELY WEAKER GFS WITH THE UKMET AND THE
PREVIOUS ECMWF RUN.


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

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

ORRISON

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