Prognostic Meteorological Discussion
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000
FXUS10 KWNH 011700
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1159 AM EST SUN FEB 01 2015

VALID FEB 01/1200 UTC THRU FEB 05/0000 UTC

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

12Z MODEL EVALUATION...INCLUDING THE NAM AND GFS


...AMPLIFIED TROUGH MOVING FROM THE CENTRAL PLAINS TO THE
NORTHEASTERN U.S. THROUGH MONDAY...
...STRENGTHENING FRONTAL WAVE...

PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: AVERAGE

A SHORTWAVE TROUGH CONTINUES TO AMPLIFY OVER THE LOWER MO VALLEY
THIS MORNING AND WILL ADVANCE PROGRESSIVELY EAST INTO THE OH
VALLEY TONIGHT AND THEN REACH SOUTHERN NEW ENGLAND BY LATER
MONDAY. MEANWHILE...SURFACE LOW PRESSURE WILL BE INTENSIFYING
THROUGH THE PERIOD AND WILL TRACK ACROSS THE MID MS VALLEY AND
NORTH OF THE OH RIVER THROUGH TONIGHT. ON MONDAY...IT WILL CROSS
THE NORTHERN MID-ATLANTIC AND REDEVELOP JUST SOUTH OF LONG ISLAND
BEFORE LIFTING TO JUST SOUTH OF NOVA SCOTIA MONDAY NIGHT. THE 12Z
NAM AND 00Z UKMET ARE A TAD FASTER AND NORTH OF THE MULTI-MODEL
CONSENSUS WITH THE LOW TRACK...ALTHOUGH THE UKMET DOES SLOW DOWN A
BIT ONCE THE LOW GETS TO OFFSHORE LONG ISLAND. THE 00Z GEM IS THE
MOST SUPPRESSED SOLUTION AND ALSO THE SLOWEST. THE 12Z GFS AND 00Z
ECMWF SPLIT THE DIFFERENCE AND SINCE THEY CLUSTER TOGETHER IN THE
MIDDLE...A BLEND OF THE GFS AND ECMWF WILL BE PREFERRED.


...SLOW-MOVING CLOSED LOW OVER MEXICO...
...SHEARING EAST TOWARD THE RIO GRANDE VALLEY/LOWER MS VALLEY BY
TUESDAY/WEDNESDAY...

PREFERENCE: BLEND OF THE 00Z ECMWF/00Z UKMET AND 00Z GEM
CONFIDENCE: AVERAGE

A CLOSED LOW OVER NORTHWEST MEXICO WILL SETTLE FARTHER SOUTH DOWN
OVER THE BAJA PENINSULA BEFORE THEN GRADUALLY PIVOTING EAST INTO
CENTRAL MEXICO AND SHEARING TOWARD THE RIO GRANDE VALLEY. THE 12Z
NAM HANGS ON TO A STRONGER CLOSED LOW/TROUGH AXIS THAT ADVANCES
ACROSS THE LOWER RIO GRANDE VALLEY ON WEDNESDAY AND THEN INTO THE
LOWER MS VALLEY. THE 12Z GFS HOWEVER BECOMES THE MOST SHEARED AND
WEAKEST WITH THE ENERGY THROUGH THE SAME TIME FRAME. THE 00Z
ECMWF/00Z UKMET AND 00Z GEM SPLIT THE DIFFERENCE. WILL PREFER A
NON-NCEP MODEL CONSENSUS.


...LOW-AMPLITUDE WAVES MOVING THROUGH THE NORTHWEST THROUGHOUT THE
PERIOD...

PREFERENCE: BLEND OF THE 12Z GFS AND 00Z ECMWF
CONFIDENCE: AVERAGE

A SERIES OF LOW-AMPLITUDE WAVES WILL TRAVERSE A MEAN LAYER RIDGE
AXIS OVER THE NORTHWEST THROUGH THE SHORT RANGE PERIOD. THE
STRONGER MODEL CLUSTERING WITH THE MEAN FLOW FAVORS A BLEND OF THE
12Z GFS AND 00Z ECMWF...AND SO WILL FAVOR A BLEND OF THESE
SOLUTIONS.


...UPPER TROUGH CROSSING THE UPPER MIDWEST BY WEDNESDAY MORNING...
...ATTENDANT COLD FRONT MOVING THROUGH THE CENTER OF THE CONUS...

PREFERENCE: BLEND OF THE 00Z ECMWF/00Z UKMET AND 00Z GEM
CONFIDENCE: AVERAGE

A BROAD AXIS OF HEIGHT FALLS ARE FORECAST TO DIG THROUGH THE UPPER
MIDWEST IN ASSOCIATION WITH A NORTHERN STREAM UPPER TROUGH. THE
12Z GFS IS THE MOST PROGRESSIVE SOLUTION WITH THE 12Z NAM THE
SLOWEST. THE 00Z ECMWF/00Z UKMET AND 00Z GEM CLUSTER IN BETWEEN
THE FASTER AND SLOWER CAMPS. WILL PREFER A NON-NCEP CONSENSUS.


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

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

ORRISON

$$




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