Prognostic Meteorological Discussion
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926
FXUS10 KWNH 130700
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MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 AM EST SAT FEB 13 2016

VALID FEB 13/0000 UTC THRU FEB 16/1200 UTC

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

...AN EVALUATION OF THE 00Z MODEL GUIDANCE ALONG WITH FINAL
PREFERENCES/FORECAST CONFIDENCE...

THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 00Z
NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.


...SHORT WAVE CROSSING NRN INTERMOUNTAIN REGION SAT TO THE ERN
GREAT LAKES/OH VALLEY MON...

PREFERENCE: NON-NAM SOLN
FORECAST CONFIDENCE: AVERAGE

THE 00Z NAM CONTINUES TO BE ON THE FAST END OF GUIDANCE ESPECIALLY
DAY 2 AND BEYOND WITH THE S/WV MOVING SEWD ACRS THE NRN
INTERMOUNTAIN REGION ON SAT AND INTO THE MIDWEST REGION ON SUN.
OVERALL JET STRUCTURE..IS CONSIDERABLY WEAKER WITH JET ACRS THE
PAC NW INTO THE CNTL PLAINS COMPARED TO MODEL
CONSENSUS...ESPECIALLY DAY 2 AND BEYOND WHICH MAKES IT MORE OF AN
OUTLIER SOLN. THE REMAINING GUIDANCE..ESPECIALLY THE GFS AND GFS
PARALLEL RUN..AS WELL AS THE UKMET/EC ARE FAIRLY WELL CLUSTERED
WITH THE TRACK/AMPLITUDE OF THIS SYSTEM AND APPEAR REASONABLE TO
USE.

..STRONG MID LEVEL ZONAL FLOW/LOW LEVEL ONSHORE FLOW PACIFIC
NORTHWEST SAT NIGHT INTO TUES MRNG...

PREFERENCE: BLEND OF NON-NAM SOLNS WITH EC MEAN
FORECAST CONFIDENCE: AVERAGE

BEHIND EXITING S/WV MOVING THRU THE NRN INTERMOUNTAIN REGION...WAA
PATRN ENSUES IN ADVANCE OF WARM FRONT SUPPORTED BY FLAT S/WV IN
INCREASINGLY STG NEAR ZONAL FLOW PUSHING INTO BC LATE SAT.  ASSOCD
COLD FRONT IS NOT FCST TO MAKE MUCH SWD PROGRESS..PERHAPS NRN WA
AS HEIGHTS ARE FCST TO SLOWLY BUILD ACRS THE ERN PAC THRU MON MRNG
BEFORE A MORE SIGNIFICANT MID/UPR LEVEL LOW IS FCST TO PUSH TOWARD
THE SW CANADA COAST MON NIGHT.  THERE IS REASONABLY GOOD AGREEMENT
WITH THIS SCENARIO WITH SOME SMALL TIMING DIFFERENCES SHOWING UP
MON/TUE MRNG WITH THE UPR LEVEL APCHG SW CANADA...WITH THE 00Z NAM
SOMEWHAT ON THE SLOWER END OF GUIDANCE..WHILE THE GFS HAS TRENDED
SLIGHTLY SLOWER THAN THE SLIGHTLY FASTER CONSENSUS. THE ENSEMBLE
GUIDANCE SHOW SOME MODEST SPREAD IN THIS AREA...SUGGESTING A BLEND
OF ENSEMBLE MEANS WITH NON-NAM SOLN MAY BE GOOD STARTING POINT.


...DEVELOPING SRN STREAM STORM SYSTEM OVER THE SOUTHERN PLAINS/LWR
MS VALLEY INTO THE MID ATLC SUN INTO TUE MRNG...

PREFERENCE:12Z/00Z GFS BLEND
FORECAST CONFIDENCE: AVERAGE

THE MAIN TREND IN THE NAM AND GFS OVER THE PAST SEVERAL RUNS IS TO
SHOW LESS AMPLIFICATION WITH LEAD S/WV THAT IS FCST TO SHARPEN
SEWD THRU THE CNTL OR SRN PLAINS AS THESE MODELS SHOW A STGR
TRAILING S/WV DIGGING SEWD TOWARD THE MID MS VALLEY AS OPPOSED TO
THE UPR MS VALLEY BY TUES MRNG.  THE END RESULT IS A MUCH FASTER
AND LESS AMPLIFIED EJECTION OF LEAD S/WV TOWARD THE MID ATLC
REGION TUES MRNG COMPARED TO THE SLOWER AND MORE AMPLIFIED 12Z
EC/UKMET SOLNS.  WHILE THE 18Z GFS WAS EVEN QUICKER..ITS SOLN WAS
FASTER THAN THE 18Z GEFS ENSEMBLE.  WHILE THERE STILL SEEM TO BE
TWO CAMPS OF SOLNS WITH THE 12Z EC AND 12Z UKMET OFFERING THE MORE
AMPLIFIED AND SLOWER SOLNS..WITH THE TREND OF THE MODELS SLOWING
MORE DIGGING OF S/WV ENERGY THRU THE MID MS VALLEY BY TUES
MRNG...THIS WOULD SUGGEST A QUICKER EJECTION OF LEAD S/WV.  A
PRELIMINARY PREFERENCE WOULD BE TO AVERAGE OUT THE 12Z AND 00Z GFS
SOLNS WHICH WOULD BE SOMEWHAT FASTER AND FLATTER SOLN TO THE 12Z
EC/12Z UKMET. UPDATED LOOK AT BOTH THE 00Z UKMET AND 00Z EC...BOTH
HAVE TRENDED FASTER AND LESS AMPLIFIED...AND MORE IN THE DIRECTION
OF OUR PRELIMINARY PREFERENCE WHICH WAS A BLEND OF THE 12Z AND 00Z
GFS.

...CLOSED MID LEVEL LOW MOVING ACRS NEW ENGLAND SAT INTO SUN
MRNG...

PREFERENCE: GENL MODEL BLEND
FORECAST CONFIDENCE: ABOVE AVERAGE

THERE APPEARS TO BE DECENT AGREEMENT WITH THE PLACEMENT AND
STRENGTH OF THE MID LEVEL VORTEX AS IT TRACKS FROM THE
ONTARIO/QUEBEC BORDER ACROSS ME..AS WELL AS WITH INVERTED TROUGH
AXIS THAT DEVELOPS BACK TOWARD THE CNTL COAST.  A GENL MODEL
COMPROMISE IS RECOMMENDED GIVEN THE SMALL BUT STILL IMPORTANT
SPREAD IN PCPN PLACEMENT.

...LOW PRES SLIDING SEWD FROM THE NRN HI PLAINS INTO THE MO VALLEY
MON/TUE MRNG...

PREFERENCE: NON-UKMET BLEND
FORECAST CONFIDENCE: AVERAGE

WHILE THE OVERALL TREND AS MENTIONED ABOVE HAS BEEN TOWARD A
SHARPER/MORE SRN TRACK WITH S/WV THAT MOVES SEWD OUT OF THE NRN HI
PLAINS ON MON TOWARD THE MO VALLEY...WITH THE EXCEPTION OF THE
UKMET...MOST GUIDANCE NOW IS FAIRLY TIGHTLY CLUSTERED IN DRIVING
ASSOCD VORT MAX INTO SW IA/MO BORDER AREA BY TUE MRNG.  THE 00Z
UKMET DIGS THIS ENERGY MORE SO THAN CONSENSUS...TOWARD SRN MO AND
WHILE THIS SOLN IS WITHIN THE SPREAD OF ENSEMBLE GUIDANCE...IT IS
ON THE EDGE OF MOST OF THE SOLNS AT THIS TIME AND THEREFORE WOULD
CONSIDER GIVING IT LESS WEIGHT.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

SULLIVAN

$$





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