Prognostic Meteorological Discussion
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000
FXUS10 KWNH 300633
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 AM EDT SAT MAY 30 2015

VALID MAY 30/0000 UTC THRU JUN 02/1200 UTC

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

00Z MODEL EVALUATION...INCLUDING THE NAM/GFS/UKMET/GEM AND ECMWF

...SHORTWAVE TROUGH THE CENTRAL PLAINS...
...MCV AND ATTENDANT SURFACE LOW OVER THE MIDDLE MS VALLEY...
...NORTHERN STREAM ENERGY CROSSING THE GREAT LAKES MON AND TUES...

PREFERENCE: 00Z GFS
CONFIDENCE: AVERAGE

THE MODELS SHOW GOOD AGREEMENT WITH THE NORTHEASTWARD ADVANCE OF
THE MCV THE THAT IS NOW OVER THE MID MS VALLEY REGION. THIS ENERGY
WILL SHEAR AND DAMPEN OUT OVER THE OH VALLEY ON SAT AS NORTHERN
STREAM ENERGY EJECTS EAST FROM THE CENTRAL PLAINS AND GRADUALLY
ADVANCES THROUGH THE OH VALLEY SAT AND SUN BEFORE WEAKENING. THE
INFUSION OF NORTHERN STREAM ENERGY SHOULD HELP TO SUSTAIN AN AREA
OF LOW PRESSURE ORIGINALLY ATTACHED TO THE MCV...AND THE MODELS
ARE IN GOOD AGREEMENT IN TRACKING THIS WAVE INTO UPPER OH VALLEY
AND MID-ATLANTIC REGION BY MON. THE 00Z ECMWF AND 00Z GEM BOTH
APPEAR A LITTLE SLOW...WITH THE 00Z UKMET A LITTLE TOO FAST. THE
00Z NAM AND 00Z GFS ARE GENERALLY WELL CLUSTERED IN BETWEEN WITH
THE DETAILS OF THIS THROUGH 48 HOURS. AFTER 48 HOURS...THE ARRIVAL
OF ADDITIONAL NORTHERN STREAM TROUGHING THROUGH THE GREAT LAKES
REGION IS EXPECTED TO CAPTURE THIS AREA OF LOW PRESSURE. ALL OF
THE MODELS TEND TO AGREE IN ELONGATING LOW PRESSURE IN A
NORTH/SOUTH FASHION OVER THE NORTHERN MID-ATLANTIC AND THE
INTERIOR OF THE NORTHEAST MON INTO TUES...BUT AFTER 48 HOURS THE
NAM IS GENERALLY EAST OF THE MULTI-MODEL CONSENSUS WITH PLACEMENT
OF THE LOW PRESSURE AREA. BASED ON THE LATEST TRENDS AND MODEL
CLUSTERING...THE GFS REMAINS A REASONABLE SOLUTION AND GIVEN
BETTER OVERALL ENSEMBLE SUPPORT...THE GFS WILL REMAIN THE
PREFERENCE.


...SHORTWAVE TROUGH OVER THE SOUTHERN ROCKIES...

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

THE 00Z NAM STILL FAVORS PORTIONS OF THE TROUGH TO SLOW DOWN AND
POSSIBLY BREAK OFF FROM THE WESTERLIES ACROSS THE MIDDLE/LOWER MS
VALLEY THROUGH THE PERIOD. THE 00Z ECMWF AND ESPECIALLY THE 00Z
UKMET ARE WEAKER AND MORE PROGRESSIVE. THE 00Z GEM TENDS TO BE A
BIT DEEPER THAN THE ECMWF AND UKMET...BUT IS FASTER THAN THE NAM
AND GFS. THE 00Z GFS WHICH HAD BEEN SLOWER/DEEPER LIKE THE NAM HAS
NOW JOINED THE NON-NCEP CAMP IN TIMING AND STRENGTH OVERALL.
THEREFORE...A NON-NAM CONSENSUS WILL BE PREFERRED...LED BY A BLEND
OF THE 00Z GFS AND 00Z ECMWF.


...SHORTWAVE TROUGH REACHING THE NORTHWEST BY MON...

PREFERENCE: BLEND OF THE 00Z NAM AND 00Z UKMET
CONFIDENCE: AVERAGE

AN UPPER LOW AND ASSOCIATED TROUGH AXIS POSITIONED NEAR 35N 147W
WILL MOVE EAST PROGRESSIVELY EAST OVER THE NEXT COUPLE OF DAYS AND
ADVANCE INTO THE NORTHWEST U.S. BY MON OUT AHEAD OF A STRONGER
CORE OF WESTERLIES AND ENERGY SOUTH OF THE ALEUTIANS. THERE IS
GENERALLY VERY GOOD AGREEMENT SEEN ALOFT AND AT THIS SURFACE
THROUGH ABOUT 72 HOURS WITH THIS SYSTEM. ALTHOUGH BY THE END OF
THE PERIOD...THE 00Z ECMWF AND 00Z GEM ARE A LITTLE SLOWER THAN
THE MULTI-MODEL CONSENSUS...WITH THE 00Z GFS FASTER. A BLEND OF
THE ECMWF AND GFS TIMING WILL BE PREFERRED WHICH IS BEST SUPPORTED
BY A BLEND OF THE 00Z NAM AND 00Z UKMET.


...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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