Prognostic Meteorological Discussion
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719
FXUS10 KWNH 260441
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1241 AM EDT FRI MAY 26 2017

VALID MAY 26/0000 UTC THRU MAY 29/1200 UTC

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

00Z NAM/GFS EVALUATION INCLUDING PRELIMINARY 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 00 UTC NAM AND GFS HAVE SHOWN GOOD RUN-TO-RUN CONTINUITY WITH
THEIR 12 UTC RUNS.  THE LATEST DETERMINISTIC MODELS REMAIN IN
OVERALL GOOD AGREEMENT WITH THIS SYSTEM.

...UPPER LOW MOVING ACROSS CENTRAL CANADA/UPPER TROUGH MOVING
ACROSS THE CENTRAL U.S. FRI-MON...
...WEAK SURFACE LOW AND FRONTAL BOUNDARY ACROSS THE LOWER/MIDDLE
MS VALLEY SAT NIGHT/SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

THE 00 UTC GFS IS SLOWER THAN ITS 12 UTC RUN WITH THE UPPER TROUGH
AS IT MOVES ACROSS THE UPPER MIDWEST/GREAT LAKES SUN-MON.  IT IS
ALSO SLOWER WITH THE TIMING of A SURFACE FRONT THAT IS FORECAST TO
PUSH EAST ACROSS THE OH VALLEY ON SUN WITH A WEAK WAVE LIFTING
NORTHEAST ACROSS THE LOWER LAKES REGION SUN NIGHT/MON MORNING.
WHILE DIFFERENCES IN THE DETAILS REMAIN...THE LATEST DETERMINISTIC
GUIDANCE HAS MOVED INTO GENERALLY GOOD AGREEMENT WITH RESPECT TO
THE LARGER SCALE FEATURES.

...MID LEVEL SHORTWAVE/SURFACE LOW TRACKING FROM THE MID MS VALLEY
TO THE OH VALLEY/GREAT LAKES ON FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS COMPROMISE
CONFIDENCE: AVERAGE

MOST OF THE GUIDANCE SHOWS A LOW-AMPLITUDE MID LEVEL
SHORTWAVE/WEAK SURFACE LOW TRACKING TO THE NORTHEAST AS IT MOVES
ACROSS THE TOP OF A SHORTWAVE RIDGE FROM THE MID MS VALLEY INTO
THE OH VALLEY LATE FRI INTO EARLY SAT.  OF THE LATEST
DETERMINISTIC MODELS...THE GFS IS AN AMPLIFIED AND MORE NORTHERLY
OUTLIER WITH THIS SYSTEM.

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

PEREIRA

$$





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