Preliminary Forecasts
Issued by NWS

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FXUS02 KWNH 010645
PREEPD

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
244 AM EDT FRI AUG 01 2014

VALID 12Z MON AUG 04 2014 - 12Z FRI AUG 08 2014

TROPICAL STORM BERTHA HAS DEVELOPED OVER THE TROPICAL WRN ATLANTIC
AND WAS LOCATED NEAR 12.3N 55.5W AT 03 UTC PACKING 40 KT SUSTAINED
WINDS WITH GUSTS TO 50 KTS. THE NATIONAL HURRICANE CENTER WILL
CONTINUE TO MONITOR BERTHA FORECAST TO TRACK ACROSS THE NERN
CARIBBEAN/ANTILLES TOWARD THE BAHAMAS AND OFF THE SERN US AS HELD
OFFSHORE BY AN ERN US MID-UPPER LEVEL TROUGH THAT PERSISTS DURING
BERTHA PASSAGE. A TRAILING WAVY FRONT WILL FOCUS
MOISTURE/CONVECTION NEAR THE ERN AND SERN US AND SLOW MOVING SRN
STREAM TAILING TROUGH/VORT ENERGY CENTERED BACK NEAR THE CENTRAL
GULF COAST STATES REMAIN A FOCUS FOR SOME HEAVY DOWNPOURS.

HIGH LATITUDE BLOCKY FLOW ESTABLISHED FROM THE NERN PACIFIC INTO
CANADA AND SRN STREAM FLOW OUT FROM THE WRN US LEADS TO
REINFORCING A MID-UPPER LEVEL TROUGH POSITION MID-LATER NEXT WEEK
BACK FROM THE N-CENTRAL US/GREAT LAKES/MIDWEST AS THE AMPLIFIED
NERN US LEAD TROUGH GRADUALLY SHIFTS EASTWARD. CENTRAL US TO GREAT
LAKE CYCLOGENSIS SHOULD FOCUS TRAILING PLAINS/MS VALLEY FRONTAL
AND WARM SECTOR CONVECTION MID-LATE NEXT WEEK FUELED BY RETURNING
GULF MOISTURE.  THIS PATTERN ALSO FAVORS LEAD THETAE ADVECTION AND
MCS/NOCTURAL CONVECTION ALONG REPEAT CELL HEAVY RAINFALL THREAT
OVER THE MIDWEST/GREAT LAKES...SPILLING INTO THE MID-ATLC.

MEANWHILE...AMPLE ENERGY ROTATING ON AMPLIFIED RIDGE PERIPHERY
THROUGH THE SWRN US/GREAT BASIN AND ROCKY STATES SHOULD FEED ON
MONSOONAL MOISTURE TO FOCUS AN ACTIVE CONVECTIVE PATTERN NEXT
WEEK...ESPECIALLY WITH FAVORED TERRAIN/UPSLOPE WHERE SOME
MODERATELY HEAVY LOCAL AMOUNTS ARE POSSIBLE.

THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE BLEND OF GENERALLY COMPATABLE GUIDANCE FROM THE 18 UTC
GFS/GFS ENSEMBLE MEAN AND 12 UTC ECMWF/UKMET/ECMWF ENSEMBLE MEAN.
CONSISTENT WITH THE OVERALL TREND TOWARD AMPLIFIED NOAM FLOW FOR
EARLY AUGUST...THESE MODEL AND ENSEMBLE MASS FIELDS SEEM
REASONABLY WELL CLUSTERED WITH RESPECT TO THE ABOVE MENTIONED
FEATURES AND SEEM TO OFFER ABOVE NORMAL WEATHER PATTERN AND
ORGANIZED SYSTEM PREDICTABILITY.

SCHICHTEL

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