Preliminary Forecasts
Issued by NWS

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000
FXUS02 KWNH 300713
PREEPD

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
312 AM EDT MON MAY 30 2016

VALID 12Z THU JUN 02 2016 - 12Z MON JUN 06 2016


...GUIDANCE/UNCERTAINTY ASSESSMENT AND PATTERN
HIGHLIGHTS/THREATS...

SLOW MOVING TROPICAL DEPRESSION BONNIE WAS LOCATED NEAR 32.8N
80.1W AT 03 UTC WITH 25 KNOT SUSTAINED WINDS AND GUSTS TO 35
KNOTS. BONNIE IS FORECAST BY THE NATIONAL HURRICANE CENTER (NHC)
TO TRANSITION INTO AN EXTRATROPICAL LOW ALONG/OFF THE CAROLINA
COAST DURING THE NEXT COUPLE OF DAYS. THE SYSTEM AND ASSOCIATED
WEATHER WILL FURTHER WEAKEN WHILE TRACKING OFFSHORE THE
MID-ATLANTIC AND NEW ENGLAND MID-LATE WEEK. PLEASE REFER TO THE
LATEST PRODUCTS FROM THE NHC AND EFFECTED NWS FORECAST OFFICES FOR
ADDITIONAL INFO ON BONNIE.

OTHERWISE...AN UNSETTLING AND AMPLIFIED NERN/ERN PACIFIC TROUGH
AND SHIELDING W-CENTRAL NORTH AMERICAN MID-UPPER LEVEL RIDGE
BUILDS OVER THE NEXT WEEK. DECENT ERN PACIFIC MID-UPPER TROUGH
ENERGY IS STILL EXPECTED TO UNDERCUT INTO CA NEXT WEEKEND AND
SPAWN LIMITED CA/SWRN US SHOWERS. THE W-CENTRAL US RIDGE ALOFT
SHOULD MEANWHILE ALLOW A SERIES OF DOWNSTREAM IMPULSES
CARVE/MAINTAIN AN EAST-CENTRAL NORTH AMERICAN MEAN TROUGH POSITION
ALOFT AND A QUITE WAVY LEAD SURFACE FRONT UNDERNEATH TO FOCUS
CONVECTION. GUIDANCE HAS TRENDED MORE AMPLIFIED WITH THIS TROUGH
AND WITH INCREASED FLOW SEPARATION/POSSIBLE CLOSED LOW DEVELOPMENT
DUG/SPLIT OVER TX. FLOW AMPLITUDE AND SLOW TRANSLATION FAVORS
PERIODS OF DEEP GULF OF MEXICO THEN ATLANTIC MOISTURE TO FUEL SOME
WIDESPREAD HEAVIER RAINS FROM THE SRN PLAINS ENEWD ACROSS THE
E-CENTRAL AND ERN US. THIS MAY BE ESPECIALLY EVIDENT OVER TX WITH
FLOW SEPARATION/REPEAT ACTIVITY. THE NOW YOU SEE IT NOW YOU DON`T
WELL ORGANIZED 12 UTC CANADIAN MODEL TROPICAL SYSTEM EFFECTING THE
SERN US LATER THIS WEEK IS INDEED NOW GONE WITH THE LATEST 00 UTC
RUN. THAT IS NOT A SURPRISE GIVEN THE HISTORICALLY HIGH CANADIAN
MODEL BIAS WITH TROPICAL DEVELOPMENTS...BUT THE OVERALL PATTERN
DOES OFFER POTENTIAL TO TAP DEEP TROPICAL MOISTURE GIVEN SRN TIER
FLOW AMPLITUDE.

THE WPC MEDIUM RANGE PRODUCT SUITE HAS BEEN PRIMARILY DERIVED FROM
A COMPOSITE BLEND OF REASONABLY WELL CLUSTERED GUIDANCE FROM THE
18 UTC GFS/GEFS AND 12 UTC ECMWF/ECMWF ENSEMBLE MEAN. APPLIED
HEAVY WEIGHTING IN THIS BLEND TO THE DETERMINISTIC MODELS DAYS 3/4
AND ENSEMBLE MEANS DAYS 5-7. LATER 00 UTC GUIDANCE IS ALSO IN LINE
WITH THIS FLOW SCENARIO. SMALLER SCALE LOCAL FOCUSING DETAILS
REMAIN PROBLEMATIC...BUT THE OVERALL FLOW OFFERS DECENT WPC
CONTINUITY AND AT OR ABOVE AVERAGE FORECAST PREDICTABILITY GIVEN
IMPROVED GUIDANCE FORECAST SPREAD AND INCREASED SYSTEM
ORGANIZATION AND CLUSTERING.

SCHICHTEL













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