Prognostic Meteorological Discussion
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FXUS02 KWBC 291508
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1107 AM EDT WED JUL 29 2015

VALID 12Z SAT AUG 01 2015 - 12Z WED AUG 05 2015

...SERN US HEAVY RAINFALL THREAT...

...MODEL/UNCERTAINTY ASSESSMENT...

THE WPC MEDIUM RANGE SURFACE FRONTS/PRESSURES AND 500 MB PROGS
ALONG WITH THE 2.5KM SENSIBLE WEATHER GRIDS HAVE BEEN PRIMARILY
DERIVED FROM REASONABLY WELL CLUSTERED GUIDANCE FROM THE 06 UTC
GFS/GEFS MEAN...00 UTC ECMWF...AND 00 UTC NAEFS/ECMWF ENSEMBLE
MEANS THIS WEEKEND. DETERMINISTIC MODEL FORECAST SPREAD INCREASES
DAYS 5-7 MON-WED...ESPECIALLY UPSTREAM ACROSS THE CHAOTIC NERN
PACIFIC. THIS SEEMS TO THEN FAVOR AN ENSEMBLE BASED SOLUTION AS A
TEMPLATE FOR MANUALLY ADDED DETAIL CONSISTENT WITH STILL
COMPATABLE GEFS/NAEFS/ECMWF ENSEMBLE MEANS. THIS FORECAST STRATEGY
MAINTAINS GOOD WPC CONTINUITY IN A PATTERN WITH OVERALL SLIGHTLY
ABOVE AVERAGE PREDICTABILITY.

...PATTERN OVERVIEW AND SENSIBLE WEATHER HIGHLIGHTS/THREATS...

MID-UPPER LEVEL RIDGING SPREADS OUT FROM THE W-CENTRAL US. EXPECT
CONTINUED MONSOONAL ACTIVTY IN THE MOISTURE PLUMED WRN PERIPHERY
THROUGH THE SWRN US AND INTERMOUNTAIN W/ROCKY STATES. PACIFIC AND
NRN STREAM IMPULSES RUNNING AROUND AND OVERTOP THE RIDGE TEND TO
DIG SEWD DOWNSTREAM UNDERNEATH A CLOSED E-CENTRAL CANADIAN VORTEX
ALOFT AND INTO A SPLIT ERN US TROUGH POSITION. ENERGY ACROSS THE
US NRN/NERN TIER WILL FORCE SEVERAL CONVECTION FOCUSING FRONTAL
SYSTEMS OVER THE REGION. LOWER LATITUDE ENERGIES WILL MEANWHILE
FOCUS WAVY FRONTAL ORGANIZATION AND DEEPER MOISTURE TO FUEL
CONVECTIVE DOWNPOURS AND A POTENTIAL HEAVY RAINFALL THREAT DOWN
ACROSS THE SERN US.

SCHICHTEL

$$




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