Prognostic Meteorological Discussion
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FXUS10 KWNH 150456
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1255 AM EDT MON SEP 15 2014

VALID SEP 15/0000 UTC THRU SEP 18/1200 UTC

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

...AN EVALUATION OF THE 00Z NAM/GFS ALONG WITH PRELIMINARY
PREFERENCES/FORECAST CONFIDENCE...

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


...BROAD LONGWAVE TROF AFFECTING THE NORTHEASTERN SECTOR OF THE
CONTINENT...
...PROGRESSIVE FRONTAL ZONE...

PRELIMINARY PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF
FORECAST CONFIDENCE: AVERAGE

AN EXPANSIVE NEGATIVE HEIGHT ANOMALY WILL CONTINUE TO DOMINATE THE
NORTHEASTERN PORTION OF NORTH AMERICA. A PRONOUNCED SHORTWAVE IS
FORECAST TO SLIDE EASTWARD FROM THE NORTHERN PLAINS INTO THE GREAT
LAKES AND NORTHEASTERN U.S. ON MONDAY/TUESDAY. BY 16/0600Z...THE
00Z GFS IS SLIGHTLY QUICKER WITH THIS SHORTWAVE RELATIVE TO OTHER
SOLUTIONS BUT THE DIFFERENCE DOES NOT APPEAR TOO MEANINGFUL. AS
TIME PROCEEDS FORWARD TO MID-WEEK...THE 00Z NAM IS MORE AGGRESSIVE
WITH THE ENERGY DIGGING TOWARD LAKE SUPERIOR. THIS CREATES A
SOLUTION THAT IS SLOWER THAN THE ENSEMBLE MEANS. DIFFERENCES GROW
TOWARD THE END OF THE PERIOD BUT THE IMPACTS ARE PRIMARILY WITH
THE HEIGHT FIELDS ACROSS EASTERN CANADA. THE COMBINATION OF THE
00Z GFS/12Z ECMWF AFFORD A REASONABLE COMPROMISE AND AGREE WITH
THE ENSEMBLE MEANS QUITE WELL.


...WEAK AREA OF LOW PRESSURE CROSSING THE WESTERN GULF OF MEXICO...

PRELIMINARY PREFERENCE: NON-12Z CMC MODEL COMPROMISE
FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE

AN AREA OF LOW PRESSURE AND THE ACCOMPANYING ENHANCED MOISTURE
FLUXES WILL ADVANCE WESTWARD REACHING EASTERN MEXICO/SOUTH TX BY
LATE MONDAY NIGHT. SOLUTIONS SLIGHTLY VARY WITH TIMING BUT ALL
SHOW SOME SORT OF DIFFUSE WAVE CROSSING SOUTH TX EARLY TUESDAY
MORNING. THE EXCEPTION TO THIS IS THE 12Z CMC WHICH ULTIMATELY
ALLOWS THE LOW TO STALL AND DUMP VERY HEAVY RAINFALL TO AN AREA
BETWEEN CORPUS CHRISTI AND BROWNSVILLE TX. WILL DISMISS THIS
SOLUTION AND FAVOR A NON-12Z CMC MODEL COMPROMISE.


...SHEARED SHORTWAVES MOVING FROM THE SOUTHERN PLAINS TOWARD THE
LOWER TN VALLEY ON DAY 1...

PRELIMINARY PREFERENCE: NON-12Z ECMWF/ECMWF ENSEMBLE MEAN MODEL
CONSENSUS
FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE

WEAKENED ENERGY WHICH LIFTED FROM THE RIO GRANDE WILL TURN TOWARD
THE EAST AS IT BECOMES CAPTURED IN THE WESTERLY FLOW ALOFT. ONLY
18 HOURS INTO THE FORECAST THE 12Z ECMWF/ECMWF ENSEMBLE MEAN ARE
SLOWER IN EJECTING THESE IMPULSES EASTWARD. EVENTUALLY THE SYSTEM
IS HARDER TO IDENTIFY AS IT SHEARS OVER THE LOWER TN VALLEY. WILL
STICK CLOSER TO THE MODEL CONSENSUS AND DISMISS THE ECMWF SUITE
FOR NOW.


...MEAN UPPER TROF AFFECTING THE EASTERN PACIFIC/IMMEDIATE WEST
COAST...

PRELIMINARY PREFERENCE: BLEND OF THE 00Z GFS/12Z ECMWF
FORECAST CONFIDENCE: AVERAGE

A LARGE RIDGE INITIALLY OVER THE WEST COAST WILL SLIDE EASTWARD
AHEAD OF AN UPPER TROF ORGANIZING ACROSS THE EASTERN PACIFIC. THE
INITIAL SHORTWAVE IS EXPECTED TO LIFT NORTHEASTWARD AND SHEAR OVER
THE COASTAL PACIFIC NORTHWEST EARLY TUESDAY. THE ORGANIZED AXIS OF
HEIGHT FALLS LURK UPSTREAM WITH THE ENERGY PROGRESSING EASTWARD
TOWARD THE WEST COAST THROUGH EARLY THURSDAY. THE ENSEMBLE MEANS
SHOW MUCH BETTER CLUSTERING THAN IN PREVIOUS DAYS WHICH INCLUDES
THE 18Z GEFS/21Z SREF/12Z ECMWF ENSEMBLE MEANS. THE 12Z CMC/UKMET
ARE WEST OF THESE SOLUTIONS WHILE THE 00Z GFS/12Z ECMWF SHOWS
GENERAL AGREEMENT WITH THE MEANS. WILL RECOMMEND THE 00Z GFS/12Z
ECMWF CLUSTER WITH THIS AREA OF THE CONUS.


...HURRICANE ODILE...

PRELIMINARY PREFERENCE: THROUGH 16/1200Z: 12Z
UKMET...THEREAFTER...12Z CMC
FORECAST CONFIDENCE: AVERAGE

THIS TROPICAL SYSTEM AS OF THE 03Z ADVISORY WAS REPORTING A
PRESSURE OF 930 MB WITH MAXIMUM SUSTAINED WINDS OF 110 KNOTS AND A
MOTION TOWARD THE NORTH-NORTHWEST AT 15 KNOTS. THE FORECAST
CARRIES ODILE RIGHT ALONG THE WEST COAST OF BAJA CA AS A HURRICANE
THROUGH TUESDAY MORNING BEFORE WEAKENING AS IT CROSSES INTO THE
GULF OF BAJA CA/SEA OF CORTEZ. THE 00Z NAM GENERALLY GOES EAST OF
THE NHC TRACK WHILE THE 00Z GFS GETS AHEAD OF THEIR SOLUTION.
MEANWHILE...THE 12Z ECMWF IS A HAIR WEST WITH THE 12Z UKMET BEING
THE CLOSEST THROUGH APPROXIMATELY 36 HOURS. THEREAFTER...THE 12Z
UKMET BECOMES FASTER WITH THE 12Z CMC FOLLOWING THE NHC TRACK MOST
CLOSELY.



...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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