Prognostic Meteorological Discussion
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FXUS10 KWNH 071629
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1128 AM EST SUN FEB 07 2016

VALID FEB 07/1200 UTC THRU FEB 11/0000 UTC

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

...AN EVALUATION OF THE 12Z NAM/GFS ALONG WITH PRELIMINARY
PREFERENCES/FORECAST CONFIDENCE...

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


...CLOSED LOW STRENGTHENING OFF THE SOUTHEASTERN U.S. COAST...
...SURFACE CYCLONE DEEPENING ALONG THE GULF STREAM...

PRELIMINARY PREFERENCE: BLEND OF THE 12Z GFS WITH THE 00Z
ECMWF/UKMET
FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE

WATER VAPOR IMAGERY THIS MORNING DEPICTED A PRONOUNCED SHORTWAVE
MOVING OFF THE GA COAST WITH LIGHT TO MODERATE RAINFALL AFFECTING
COASTAL REGIONS OF NC/SC. AT THE SURFACE...A CYCLONE SHOULD
CONTINUE TO DEEPEN IN THE PRESENCE OF A STRENGTHENING UPPER LOW
WHILE TRACKING OVER THE GULF STREAM. THE ENTIRE SYSTEM IS FORECAST
TO QUICKLY LIFT TOWARD THE NORTH-NORTHEAST WITH POTENTIAL IMPACTS
OVER SECTIONS OF NEW ENGLAND BASED ON A RECENT WESTWARD TREND IN
THE 12Z NAM/GFS. THIS SHIFT GENERALLY ALIGNS WITH THE LOW TRACKS
OF OTHER MODELS EXCEPT FOR THE 06Z GEFS MEAN WHICH REMAINS TO THE
EAST AS THE SYSTEM NEARS NOVA SCOTIA BY 09/1200Z. THE CONSENSUS
FORMED SEEMS REASONABLE TO FOLLOW HERE BUT WILL ADHERE CLOSER TO
THE CENTER OF THE CLUSTER. THE 12Z NAM/09Z SREF MEAN ARE PERHAPS
TOO FAR WEST LATE IN THE PERIOD. THE WPC PREFERENCE WILL BE BASED
ON THE 12Z GFS AND 00Z ECMWF/UKMET WITH SUPPORT FROM THE 00Z ECMWF
ENSEMBLE MEAN.


...UPPER TROUGH CURRENTLY CLIPPING NORTHERN ME...

PRELIMINARY PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: HIGH

AN ACTIVE NORTHERN STREAM HAS BROUGHT A SHORTWAVE WHICH HAS
SHARPENED OVER EXTREME NORTHERN ME. THIS SYSTEM IS CURRENTLY
EXITING THE CONUS WITH NO DISCERNIBLE DIFFERENCES NOTED. A GENERAL
MODEL COMPROMISE IS WARRANTED HERE.


...BROAD SHORTWAVE DIGGING THROUGH THE UPPER MIDWEST THIS
MORNING...
...EVENTUAL CLOSED LOW MIGRATING FROM THE UPPER GREAT LAKES TO THE
OH VALLEY...
...PAIR OF SURFACE CYCLONES AFFECTING THE GREAT LAKES AND VA
CAPES...RESPECTIVELY...

PRELIMINARY PREFERENCE: BLEND OF THE 12Z GFS/06Z GEFS MEAN
FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE

A BROAD UPPER TROUGH MOVING THROUGH THE NORTHERN PLAINS/UPPER
MIDWEST HAS SPREAD LIGHT SNOW TO THE REGION WITH GUSTY WINDS IN
ITS WAKE. ALL OF THIS SHORTWAVE ENERGY WILL TRANSLATE EASTWARD
WITH HEIGHT FALLS SPREADING THROUGH THE OH/TN VALLEYS DOWN INTO
THE SOUTHERN TIER OF THE U.S. COMPARING RECENT GUIDANCE...THE 00Z
ECMWF/09Z SREF MEAN ARE A LOT SLOWER IN EJECTING THE TROUGH
EASTWARD FROM THE OH VALLEY TOWARD THE CENTRAL APPALACHIANS ON
MONDAY. THIS HAS IMPACTS ON THE EVENTUAL SURFACE DEVELOPMENT WHICH
UNFOLDS IN THE SOUTHERN MID-ATLANTIC BY 09/0000Z. RECENT ENSEMBLE
LOW PLOT COMPARISONS SHOW THE ECMWF HAS TRENDED SLOWER WITH ONLY A
FEW MEMBERS INDICATING LOW FORMATION BY MONDAY EVENING.
ADDITIONALLY...ITS SOLUTIONS REMAIN SOUTH OF THE MEMBERS WITH THE
00Z ECMWF/ECMWF ENSEMBLE MEAN REMAINING A POSSIBLE SOUTHERN
OUTLIER. IT LOOKS LIKE THE GFS SUITE HAS BEEN THE MOST CONSISTENT
AND ALSO RESIDES AT THE CENTER OF THE FORECAST SPREAD. GIVEN THERE
IS STILL SOME UNCERTAINTY IN THE FORECAST...WILL UTILIZE THE
MIDDLE OF THE ROAD SOLUTION WITH A BLEND OF THE 12Z GFS/06Z GEFS
MEAN BEING FAVORED AT THIS TIME.


...ELONGATED MID-LEVEL WEAKNESS ACROSS THE SUBTROPICAL EASTERN
PACIFIC INTO MX...

PRELIMINARY PREFERENCE: THROUGH 10/0000Z: GENERAL MODEL
COMPROMISE...THEREAFTER: BLEND OF THE 06Z GEFS/00Z ECMWF ENSEMBLE
MEANS
FORECAST CONFIDENCE: HIGH...THEN BECOMING AVERAGE

SOUTH OF THE BUILDING UPPER RIDGE ACROSS THE WESTERN U.S...AN
ELONGATED AXIS OF VORTICITY WILL NOSE EASTWARD ACROSS THE
SUBTROPICAL PACIFIC. GRADUAL ORGANIZATION IS FORECAST AS A WEAK
UPPER LOW FORMS IN THE VICINITY OF THE SOUTHERN EDGE OF THE GULF
OF CA/SEA OF CORTEZ BY 09/1200Z. SOME DIFFERENCES EMERGE BY DAY 3
AS THE SYSTEM DIPS DOWN TOWARD SOUTHERN MX. THE 12Z NAM MOVES TO
THE FASTER SIDE OF THE SPREAD WHILE THE DEEPER 00Z ECMWF BECOMES A
BIT TOO SLOW. HOWEVER...THOUGH DAY 2...ALL SOLUTIONS CLUSTER WELL
WHICH WARRANTS A GENERAL MODEL COMPROMISE. THEREAFTER...WILL
UTILIZE ENSEMBLE MEANS GIVEN THE SPREAD ACROSS THE SUBTROPICAL
LATITUDES OF MX.


...SYSTEMS TRACKING THROUGH THE WESTERN PACIFIC TOWARD BRITISH
COLUMBIA...

PRELIMINARY PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: AVERAGE

A STOUT RIDGE REMAINS A MAINSTAY FEATURE FOR MUCH OF THE EARLY TO
MIDDLE PART OF NEXT WEEK. MULTIPLE FEATURES DENT THE WESTERN SIDE
OF THE RIDGE WITH THE SHORTWAVE ENERGY RACING UP TOWARD BRITISH
COLUMBIA. THERE ARE GENERAL TIMING/AMPLITUDE DIFFERENCES BUT THESE
APPEAR TO BE RESTRICTED TO THE OFFSHORE PACIFIC WATERS AND INTO
WESTERN CANADA. WITH THAT BEING SAID...A GENERAL MODEL COMPROMISE
WILL BE RECOMMENDED.


...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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