Prognostic Meteorological Discussion
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000
FXUS10 KWNH 261605
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1204 PM EDT TUE MAY 26 2015

VALID MAY 26/1200 UTC THRU MAY 30/0000 UTC

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

12Z NAM/GFS EVALUATION AND PRELIMINARY PREFERENCES

UPPER LOW OVER THE PACIFIC NORTHWEST...

PREFERENCE: BEFORE 00Z FRI...NAM OR GFS OR ECMWF
             AFTER 00Z FRI...GFS OR ECMWF
CONFIDENCE: ABOVE AVERAGE

MODELS SHOW GOOD AGREEMENT THROUGH 00Z FRI...BY WHICH TIME THE NAM
DISPLAYS SOME GRID-SCALE FEEDBACK ALONG THE COLORADO/KANSAS
BORDER...WHICH THEN INTERACTS WITH SOUTHERN PORTIONS OF THE UPPER
LOW AS IT MOVES OUT OF THE NORTHERN ROCKIES.  THUS...THE NAM IS
CONSIDERED USEFUL UNTIL ABOUT 00Z FRI...BEFORE BECOMING LESS
USEFUL WITH A SWITCH TO EITHER THE GFS OR ECMWF AFTER 00Z FRI.

LOW PRESSURE NEAR IOWA...
SHORTWAVE TROUGH OVER WEST TEXAS...
SHORTWAVE TROUGH OVER THE CENTRAL GULF COAST...

MODELS SHOW GOOD LARGE-SCALE AGREEMENT. REFER TO THE QPFPFD FOR
MORE INFORMATION ON RAINFALL.

SHORTWAVE TROUGH CROSSING THE S. ROCKIES THU-FRI...

PREFERENCE: EQUAL BLEND GFS/ECMWF
CONFIDENCE: ABOVE AVERAGE

DUE TO QUESTIONABLE INTERACTIONS WITH THE NORTHERN STREAM...THE
NAM GRADUALLY MOVES TOWARD THE FAST EDGE OF THE GUIDANCE...AND
THUS IS DISCOUNTED IN FAVOR OF A GFS/ECMWF BLEND WHICH HAVE THE
BULK OF ENSEMBLE SUPPORT.

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

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

JAMES

$$





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