Prognostic Meteorological Discussion
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496
FXUS10 KWNH 061847
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
146 PM EST SAT FEB 06 2016

VALID FEB 06/1200 UTC THRU FEB 10/0000 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.


...UPPER TROUGH DIGGING THROUGH THE NORTHEASTERN GULF OF MX LATE
TONIGHT...
...RAPIDLY DEEPENING SURFACE LOW LIFTING UP THE WESTERN ATLANTIC...

FINAL PREFERENCE: BLEND OF THE 12Z ECMWF/UKMET
FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE

SPLIT FLOW REMAINS OVER THE CONUS WITH A PRONOUNCED SOUTHERN
STREAM SHORTWAVE CURRENTLY MOVING THROUGH THE LOWER MS VALLEY.
PRECIPITABLE WATER VALUES ARE RATHER LOW ACROSS THE GULF COAST AS
A PREVIOUS FRONTAL PASSAGE SCOURED OUT MUCH OF THE TROPOSPHERIC
MOISTURE. THIS SYSTEM IS FORECAST TO INTENSIFY ACROSS THE
NORTHEASTERN GULF OF MX WHERE A CLOSED LOW DEVELOPS BY SUNDAY
MORNING. ULTIMATELY THIS FORMS A SURFACE LOW OFF THE SOUTHEASTERN
U.S. COAST WHICH IS EXPECTED TO RAPIDLY STRENGTHEN. THE 12Z NAM
BEGINS ON THE FAR WESTERN SIDE OF THE SPREAD PER COMPARISONS WITH
ENSEMBLE LOW PLOTS. THESE LATTER SCATTER DIAGRAMS SHOW DIFFERENT
CAMPS SETTING UP WITH THE 00Z CMC MEMBERS BEING ON THE QUICKER
SIDE WITH A BIT MORE CLUSTERING AMONG THE 00Z GEFS/ECMWF ENSEMBLE
MEMBERS. AS THE SYSTEM ACCELERATES TOWARD THE
NORTH-NORTHEAST...THE 12Z NAM/CMC ARE ON THE WESTERN SIDE OF THE
MODEL SPREAD WITH THE ONLY SUPPORT FROM THE 09Z SREF MEAN.
THROUGHOUT THE PERIOD...THE 12Z/00Z ECMWF/UKMET SHOW THE MOST
AGREEMENT TOWARD THE 12Z GEFS/00Z ECMWF ENSEMBLE MEANS. WILL LEAN
IN THE DIRECTION OF THESE SOLUTIONS HERE.


...NORTHERN STREAM FEATURE CLIPPING UPPER NEW ENGLAND EARLY
SUNDAY...

FINAL PREFERENCE: GENERAL MODEL COMPROMISE
FORECAST CONFIDENCE: ABOVE AVERAGE

AMPLIFICATION TAKES PLACE OVER ONTARIO/QUEBEC WHICH DRAGS WEAK
HEIGHT FALLS THROUGH UPPER SECTIONS OF NEW ENGLAND ON SUNDAY
MORNING. THERE ARE SMALL-SCALE DIFFERENCES WITH THIS EVOLUTION BUT
THESE DO NOT APPEAR TO BE DETRIMENTAL TO THE FORECAST. A GENERAL
MODEL COMPROMISE APPEARS REASONABLE WITH THIS SYSTEM.


...PROGRESSIVE SHORTWAVE TRACKING FROM THE UPPER INTERMOUNTAIN
WEST TO THE GREAT LAKES...
...EVENTUAL DEEP UPPER TROUGH ANCHORING THE EASTERN U.S. ON
MONDAY/TUESDAY...
...ASSOCIATED SURFACE CYCLONES...

FINAL PREFERENCE: BLEND OF THE 06Z GEFS/00Z ECMWF ENSEMBLE MEANS
FORECAST CONFIDENCE: SLIGHTLY BELOW AVERAGE

PROGRESSIVE HEIGHT FALLS MOVING THROUGH THE UPPER INTERMOUNTAIN
WEST WILL EVENTUALLY REACH THE UPPER MIDWEST BY 07/1200Z WITH A
CLOSED LOW EVOLVING DURING THIS PROCESS. THE PATTERN APPEARS TO BE
REASONABLY RESOLVED THROUGH THE WEEKEND WITH ENSEMBLE LOW PLOTS
INDICATING MINIMAL SURFACE CYCLONE SPREAD. THIS SOLUTION IS
CENTERED OVER NORTHERN WI WITH SPREAD GRADUALLY INCREASING AS TIME
MOVES ON. LIKE PRECEDING SYSTEMS...THE TROUGH WILL QUICKLY GAIN
AMPLITUDE OVER THE MIDDLE MS VALLEY WITH THIS SHORTWAVE ENERGY
ADVANCING TOWARD THE OH VALLEY/MID-ATLANTIC REGION. MODEL
UNCERTAINTY CONTINUES TO INCREASE...PARTICULARLY WITH TIMING WITH
THE 00Z GEFS/CMC ENSEMBLE MEMBERS ON THE QUICKER SIDE. THERE HAS
BEEN A RECENT TREND IN 12Z GUIDANCE TO BE QUICKER THAN THEIR
PRECEDING RUNS. REGARDING SURFACE DEVELOPMENT...WHILE THE INITIAL
SURFACE LOW MIGRATES TOWARD THE LOWER GREAT LAKES EARLY NEXT
WEEK...A SECONDARY AXIS OF LOW PRESSURE FORMS OVER THE LOWER
MID-ATLANTIC. THE PAST FEW ENSEMBLE LOW PLOTS SHOW THE ECMWF
ENSEMBLES HAVE SUPPORTED A LOW MOVING ALONG THE VA/NC BORDER ON
MONDAY EVENING. THE 12Z ECMWF CONTINUES TO BE SOUTH OF ALL OTHER
SOLUTIONS BUT IT DID MAKE A MOVE NORTHWARD. THIS KEEPS THE
FORECAST SOUTH OF THE ENSEMBLE MEANS HOWEVER. OTHER GUIDANCE HAVE
ALSO RECENTLY TRENDED NORTHWARD...PARTICULARLY THE 12Z GFS. NOT
COMPLETELY SOLD ON ANY DETERMINISTIC SOLUTION GIVEN THE
UNCERTAINTY IN THE PATTERN. THUS...WILL MAINTAIN THE PREVIOUS
PREFERENCE.


...BROAD MID-LEVEL WEAKNESS EXTENDING OVER THE EASTERN SUBTROPICAL
PACIFIC...

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

HEIGHTS WILL QUICKLY BUILD OVER THE WESTERN U.S. SETTING UP AN
IMPRESSIVE 588-DM RIDGE. TO THE SOUTH...MODELS SHOW A BROAD
CYCLONIC CIRCULATION STRETCHING BETWEEN 20N AND 30N ACROSS THE
SUBTROPICAL EASTERN PACIFIC. THIS EXTENSIVE AXIS OF VORTICITY IS
FORECAST TO DRIFT EASTWARD TOWARD THE SOUTHERN GULF OF CA/SEA OF
CORTEZ. THE 12Z NAM IS A BIT WEST OF THE CONSENSUS FORMED BY THE
ENSEMBLE MEANS. THE BEST SUPPORT COMES FROM THE 12Z
GFS/ECMWF/UKMET ALTHOUGH THE 12Z/00Z ECMWF SOLUTION MAY BE A TAD
TOO ROBUST. WILL COMBINE THE SOLUTIONS FROM THESE THREE WHICH
SHOULD TEMPER THE STRONGER 12Z/00Z ECMWF SOME.


...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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