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765
FXUS10 KWNH 251638
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1236 PM EDT THU MAY 25 2017

VALID MAY 25/1200 UTC THRU MAY 29/0000 UTC

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

12Z NAM/GFS EVALUATION INCLUDING INITIAL PREFERENCES AND FORECAST
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


...CLOSED UPPER LOW MOVING FROM THE OHIO VALLEY TO THE MIDDLE
ATLANTIC TODAY AND EXITING NEW ENGLAND FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

THE LATEST DETERMINISTIC MODELS REMAIN IN GOOD AGREEMENT WITH THE
LARGER SCALE FEATURES OF THIS SYSTEM AS IT MOVES FROM THE OH
VALLEY TODAY TO THE NORTHERN NEW ENGLAND COAST BY LATE FRI.


...UPPER TROUGH TRAILING SOUTHWEST FROM THE CLOSED LOW OVER
SASKATCHEWAN ACROSS THE NORTHERN ROCKIES AND PACIFIC
NORTHWEST...MOVING ACROSS THE CENTRAL GREAT BASIN FRI AND THE
CENTRAL ROCKIES SAT...
...WEAK SURFACE LOW AND FRONTAL BOUNDARY ACROSS THE LOWER/MIDDLE
MS VALLEY SAT NIGHT/SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE

OVER THE LAST COUPLE MODEL CYCLES WE HAVE SEEN A GENERAL TREND
TOWARD BETTER MODEL AGREEMENT...AND THIS APPEARS TO BE CONTINUING
WITH THE 12Z MODEL RUNS. IN FACT THE 12Z NAM...12Z GFS...AND 00Z
NON-NCEP MODELS HAVE CONVERGED TOWARD A COMMON SOLUTION THROUGH
SAT AND NOW FORM A RATHER TIGHT CLUSTER. THE SHORTWAVE WILL BE
SOMEWHAT WEAKER SAT NIGHT/SUN AS IT MOVES INTO THE
CENTRAL/SOUTHERN PLAINS...BUT IT WILL PLAY A ROLE IN THE FORMATION
OF A SURFACE FRONTAL BOUNDARY THAT WILL LIKELY EXTEND FROM THE
SOUTHERN PLAINS ACROSS THE LOWER/MIDDLE MS VALLEY. EVEN THROUGH
SUN...THE MODEL MASS FIELDS ARE FAIRLY SIMILAR...BUT THERE ARE
BIGGER DIFFERENCES WITH THE SURFACE PRESSURE PATTERN AND
ESPECIALLY WITH THE QPF FIELDS. THE 12Z GFS...THE 00Z ECMWF...AND
00Z GEFS SHOW THE PRECIPITATION BAND FURTHER SOUTH...AND THAT
LOOKS LIKE THE MOST PROBABLE SCENARIO AT THIS POINT. THE 12Z
NAM...00Z UKMET...AND TO A LESSER DEGREE THE 00Z CMC PLACE THE
PRECIPITATION A BIT FURTHER NORTH WHICH DOES NOT LOOK CORRECT. IN
ADDITION THE UKMET PRECIPITATION AMOUNTS LOOKS CONSIDERABLY
OVERDONE. EVEN ACCOUNTING FOR THE QPF DIFFERENCES...A GENERAL
MODEL BLEND SHOULD STILL YIELD A REPRESENTATIVE FORECAST.


WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/

MCDONNAL

$$





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