Prognostic Meteorological Discussion
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FXUS10 KWNH 271914
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
314 PM EDT SUN JUL 27 2014

VALID JUL 27/1200 UTC THRU JUL 31/0000 UTC

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

...AN EVALUATION OF THE 12Z CMC/UKMET/ECMWF ALONG WITH FINAL
PREFERENCES/FORECAST CONFIDENCE...

THERE DID NOT APPEAR TO BE ANY INITIALIZATION ERRORS WITH THE 12Z
NAM/GFS DEEMED SIGNIFICANT ENOUGH TO IMPACT THEIR FORECASTS.


...DYNAMIC UPPER LOW RACING FROM THE UPPER GREAT LAKES TOWARD THE
UPPER MID-ATLANTIC...
...ASSOCIATED SURFACE LOW/BAROCLINIC ZONE...

FINAL PREFERENCE: BLEND OF THE 12Z GFS/ECMWF
FORECAST CONFIDENCE: AVERAGE

AN ANOMALOUS CLOSED LOW SPINNING OVER NORTHERN WI/UPPER PENINSULA
OF MI WILL CONTINUE TO SLIDE ACROSS THE GREAT LAKES TODAY BEFORE
REACHING THE UPPER MID-ATLANTIC BY 28/1200Z. THROUGH EARLY
MONDAY...MODELS ARE IN FAIRLY GOOD AGREEMENT CARRYING THE HEIGHT
FALLS THROUGH NORTHERN PA/SOUTHWESTERN NY. THE GUIDANCE DO VARY
WITH THE INTENSITY OF THE SURFACE LOW HOWEVER. IT APPEARS THE 12Z
CMC HAS SLOWED ENOUGH TO BRING IT BACK TO THE CONSENSUS BUT THE
12Z UKMET REMAINS ONE OF THE SLOWER/DEEPER SOLUTIONS. THIS THEME
CONTINUES FOR THE 12Z UKMET WHICH MAKES IT MORE OF AN OUTLIER
SOLUTION HERE. THE 12Z NAM/GFS/ECMWF APPEAR REASONABLE BUT THE
BIGGER ISSUE IS DIFFERENCES ALONG THE WESTERN FLANK OF THE
BAROCLINIC ZONE SETTING UP ACROSS THE SOUTHERN/CENTRAL HIGH
PLAINS. THE POSITION OF THIS FRONT/ASSOCIATED MOISTURE TRANSPORT
WILL PLAY A KEY ROLE IN THE HEAVY PRECIPITATION EXPECTED ON DAYS
2/3 ACROSS THE REGION. THE 12Z NAM/GFS ARE MORE AGGRESSIVE WITH
LOW-LEVEL INFLOW WITH THE 12Z NAM EVENTUALLY BECOMING AN EASTERN
OUTLIER WITH THE AREA OF LOW PRESSURE. GIVEN ALL OF THE
ABOVE...WILL FAVOR A BLEND OF THE 12Z GFS/ECMWF BUT CONFIDENCE
WILL BE KEPT CLOSER TO AVERAGE.


...MEAN UPPER TROF ANCHORING NORTHEASTERN NORTH AMERICA...

FINAL PREFERENCE: BLEND OF THE 12Z GEFS/09Z SREF/00Z ECMWF
ENSEMBLE MEANS
FORECAST CONFIDENCE: SLIGHTLY ABOVE AVERAGE

A FULL-LATITUDE NEGATIVE HEIGHT ANOMALY WILL BE A MAINSTAY
SYNOPTIC FEATURE TO CONCLUDE THE MONTH OF JULY. THE GUIDANCE
DEPICT 500-MB HEIGHT ANOMALIES DROPPING INTO THE 2 TO 3.5 STANDARD
DEVIATION BELOW NORMAL THROUGHOUT THE PERIOD. WHILE DETAIL
DIFFERENCES ARE EVIDENT IN THE STRUCTURE OF THE BROAD CYCLONIC
VORTEX...THEY AGREE ON LOWER HEIGHTS BEING CENTERED OVER SOUTHERN
HUDSON BAY DOWN TOWARD SOUTHERN ONTARIO/QUEBEC. WILL FAVOR A BLEND
OF THE CLUSTERED ENSEMBLE MEANS GIVEN THE SUBTLE DISAGREEMENTS
AMONG THE DETERMINISTIC RUNS.


...MULTITUDE OF SHORTWAVES MEANDERING ABOUT THE CENTRAL GREAT
BASIN/ROCKIES...

FINAL PREFERENCE: BLEND OF THE 12Z GEFS/00Z ECMWF ENSEMBLE MEANS
FORECAST CONFIDENCE: LOW

MODELS DEPICT A COMPLEX EVOLUTION ACROSS THE SOUTHWESTERN QUADRANT
OF THE CONUS. A BROAD MID-LEVEL ANTICYCLONE CENTERED OVER THE FOUR
CORNERS REGION/SOUTHERN PLAINS WILL STEER MONSOONAL
ENERGY/MOISTURE NORTHWARD INTO THE CENTRAL GREAT BASIN BEFORE
TURNING EASTWARD ABOVE THE RIDGE. A SURGE OF MORE POTENT SHORTWAVE
ENERGY IS FORECAST TO APPROACH THE NV/ID/UT AREA ON 30/0000Z. THE
12Z NAM/GFS SPLIT THE ENERGY INTO TWO WHILE THE OTHER GUIDANCE
CARRY MORE FOCUS WITH ONE DISTINCT WAVE NEARING THE GREAT SALT
LAKE ON TUESDAY EVENING. SPREAD CONTINUES TO GROW AND REMAINS HIGH
WITH A GREAT AMOUNT OF UNCERTAINTY AT HAND. ENSEMBLE MEANS
DISAGREE WITH THE POSITION OF THE SHORTWAVES SO WILL BLEND THESE
UNTIL THE GUIDANCE SHOWS SIGNS OF SOLVING THIS COMPLEX PATTERN.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...
...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

RUBIN-OSTER

$$





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