Prognostic Meteorological Discussion
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000
FXUS10 KWNH 111856
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
155 PM EST THU FEB 11 2016

VALID FEB 11/1200 UTC THRU FEB 15/0000 UTC

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

...AN EVALUATION OF THE 12Z MODEL GUIDANCE ALONG WITH FINAL
PREFERENCES/FORECAST CONFIDENCE...

THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 12Z
NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.


...ELONGATED SHORTWAVE LIFTING THROUGH THE NORTHEASTERN U.S.
TODAY...

FINAL PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: HIGH

BROAD CYCLONIC FLOW ANCHORS MUCH OF CENTRAL/EASTERN CANADA WITH AN
EMBEDDED SHORTWAVE CURRENTLY SPINNING ACROSS UPSTATE NY. MODELS
EXHIBIT GOOD AGREEMENT LIFTING THIS SYSTEM UP TOWARD NOVA SCOTIA
DURING THE NEXT 12 TO 24 HOURS WHICH WARRANTS A GENERAL MODEL
COMPROMISE.


...CLIPPER SYSTEM/DEVELOPING SURFACE LOW AFFECTING THE CAROLINAS
ON FRIDAY...

FINAL PREFERENCE: BLEND OF THE 12Z GFS/ECMWF
FORECAST CONFIDENCE: AVERAGE

A CLIPPER SYSTEM SEEN ON WATER VAPOR IMAGERY MOVING THROUGH THE
NORTHERN HIGH PLAINS IS SPREADING LIGHT SNOW TO SECTIONS OF THE
DAKOTAS AND MIDDLE MS VALLEY THIS AFTERNOON. THIS FEATURE QUICKLY
TRANSLATES SOUTHEASTWARD REACHING THE SOUTHERN APPALACHIANS BY
12/1800Z. ULTIMATELY THIS INDUCES AN AREA OF LOW PRESSURE OFF THE
NC COAST BY FRIDAY AFTERNOON. THERE ARE SUBTLE DIFFERENCES AMONG
THE SOLUTIONS WHICH HAS IMPACTS ON THE OUTER BANKS. CURRENTLY THE
12Z NAM/09Z SREF MEAN ARE ON THE STRONGER/WESTERN SIDE OF THE
SOLUTION ENVELOPE WHILE THE 12Z/00Z UKMET REMAIN FLATTER/MORE
SUPPRESSED. THE BEST MIDDLE GROUND AT THIS POINT WOULD BE A BLEND
OF THE 12Z GFS/ECMWF.


...COLD UPPER VORTEX SWEEPING THE NORTHEAST THIS WEEKEND...
...POLAR FRONT/SURFACE CYCLONE CROSSING ME...

FINAL PREFERENCE: BLEND OF THE 12Z GFS/ECMWF
FORECAST CONFIDENCE: AVERAGE

A STRONG LOBE OF VORTICITY ACCOMPANIED BY SUB-492 DM HEIGHTS IS
CURRENTLY CENTERED OVER HUDSON BAY. MODELS AGREE ON ADVECTING THIS
SYSTEM SOUTHEASTWARD WITH ARCTIC AIR SURGING FROM THE GREAT LAKES
TO THE NORTHEASTERN U.S. FOR THIS WEEKEND. AS HAS BEEN THE CASE IN
RECENT DAYS...ECMWF ENSEMBLE MEMBERS HAVE FAVORED A MORE AMPLIFIED
PATTERN. THESE MEMBERS HAVE GRADUALLY RELAXED IN RECENT CYCLES
COMING CLOSER TO OTHER MODEL SOLUTIONS. THE 00Z ECMWF/ECMWF
ENSEMBLE ARE SLOWER TO ADVANCE THE UPPER VORTEX EASTWARD COMPARED
TO THE QUICKER 12Z GFS/GEFS MEAN. WILL TAKE A SPLIT OF THESE TWO
CAMPS HERE.


...PROGRESSIVE SHORTWAVE PUSHING FROM THE PACIFIC NORTHWEST TO THE
GREAT LAKES...

FINAL PREFERENCE: BLEND OF THE 12Z GFS/ECMWF WITH THE 00Z ECMWF
ENSEMBLE MEAN
FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE

UPPER RIDGING ACROSS THE WESTERN U.S. WILL BREAK DOWN IN RESPONSE
TO A PACIFIC SYSTEM WHICH WILL REACH THE WA BORDER BY EARLY
FRIDAY. THE 12Z NAM IS QUICKER TO ADVANCE THE LEADING EDGE OF
HEIGHT FALLS THROUGH THE PACIFIC NORTHWEST ON FRIDAY. TRAILING
ENERGY SPILLS IN ITS WAKE LEADING TO A MORE ELONGATED SYSTEM
STRETCHING ACROSS THE NORTHWESTERN TIER. WHILE FASTER WITH THE
INITIAL IMPULSE...THE OVERALL ADVANCE OF THE TROUGH ITSELF IS
SLOWER IN THE 12Z NAM WITH THE 12Z UKMET MOVING TOWARD THE MORE
AMPLIFIED SIDE. ENSEMBLE SPAGHETTIS SHOW SOME AMPLITUDE SPREAD
WITH MANY OF THE 00Z GEFS MEMBERS FAVORING MORE AMPLIFICATION
ACROSS THE CENTRAL PLAINS ON SUNDAY MORNING. HOWEVER...THE
ENSEMBLE MEAN ITSELF STAYS TO THE NORTH WHERE THE BETTER
CLUSTERING IS. THE OVERALL EVOLUTION OF THIS SYSTEM IS COMPLICATED
GIVEN THE NUMBER OF SHORTWAVES INVOLVED. THE BEST ENSEMBLE SUPPORT
NOTED IN RECENT SPAGHETTI DIAGRAMS IS FROM THE 00Z ECMWF ENSEMBLE
MEAN. WPC FAVORS A BLEND OF THE 12Z GFS/ECMWF WITH INCLUSION OF
THE 00Z ECMWF ENSEMBLE MEAN TO ACCOUNT FOR GROWING UNCERTAINTIES.


...ADDITIONAL PACIFIC ENERGY SWINGING THROUGH THE NORTHERN ROCKIES
BY 15/0000Z...

FINAL PREFERENCE: BLEND OF THE 12Z GEFS/00Z ECMWF ENSEMBLE MEANS
FORECAST CONFIDENCE: BELOW AVERAGE

TRAILING IN THE WAKE OF THE LEAD SYSTEM WILL BE AN ELONGATED
IMPULSE WHICH TRACKS ALONG THE EASTERN EDGE OF A RENEWED UPPER
RIDGE ACROSS THE IMMEDIATE WEST COAST. THERE ARE A SLEW OF
SCENARIOS HERE BASED ON RECENT DETERMINISTIC GUIDANCE. THE 12Z GFS
TRACKS THE FEATURE THROUGH WESTERN WY WHILE THE 12Z ECMWF FAVORS A
MORE ELONGATED SYSTEM ALONG THE ENTIRE EXTENT OF THE
NORTHERN/CENTRAL HIGH PLAINS. WILL CONTINUE TO TAKE IS THE
ENSEMBLE ROUTE FAVORING A BLEND OF THE 12Z GEFS/00Z ECMWF ENSEMBLE
MEANS.


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

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

RUBIN-OSTER

$$




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