Prognostic Meteorological Discussion
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FXUS02 KWBC 031552
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1152 AM EDT TUE MAY 03 2016

VALID 12Z FRI MAY 06 2016 - 12Z TUE MAY 10 2016

...OVERVIEW AND GUIDANCE PREFERENCES...

CLOSED LOW SEASON CONTINUES OVER THE CONUS BUT WILL BREAK DOWN
NEXT WEEK INTO MUCH LESS BLOCKY FLOW. THE MODELS AND ENSEMBLES
HAVE COME INTO MUCH BETTER AGREEMENT OVER THE PAST FEW RUNS THAN
24-36 HRS AGO, AND A CONSENSUS BLEND SUFFICES FOR THE START OF THE
PERIOD FRI-SAT. IN THE WEST, THE CUTOFF UPPER LOW WILL SLOWLY
SLIDE EAST-NORTHEASTWARD THROUGH THE PERIOD AND ONLY TRAVEL FROM
SOUTHERN CALIFORNIA TO THE UPPER MIDWEST OVER FIVE DAYS. 00Z
ECMWF/CANADIAN WERE QUICKER THAN THE 06/00Z GFS RUNS BUT WITHIN
THE ENSEMBLE SPREAD. BIGGER DIFFERENCE SEEN IN SW CANADA
YESTERADAY HAVE TRENDED TOWARD THE ECMWF-LED SOLUTION OF BRINGING
A TROUGH ACROSS BRITISH COLUMBIA SUNDAY WITH THE GEFS MEMBERS LAST
TO SHOW THIS SOLUTION (AS THEY ARE STILL HOLDING ONTO WEAK RIDGING
OR FLAT FLOW). IN THE NORTHEAST, DEPARTING LED UPPER LOW WILL EXIT
INTO THE ATLANTIC ONLY TO BE REPLACED BY CANADIAN TROUGHING THAT
MAY WRAP INTO ANOTHER OCCLUDED SYSTEM NEXT SUN/MON IN QUEBEC OR
NORTHERN NEW ENGLAND BEFORE LIFTING NORTHEASTWARD. 00Z
GFS/ECMWF/CANADIAN WERE CLOSER TO THE ENSEMBLE MEANS WHILE THE 06Z
GFS WAS SLOWER AND FARTHER SOUTH. TRANSITIONED TO A BLEND OF THE
00Z ECMWF/CANADIAN/ECENS MEAN NEXT MON-TUE WHICH WAS MORE
AMPLIFIED THAN THE GEFS/NAEFS MOSTLY DUE TO THE DIFFERENCES OVER W
CANADA.


...WEATHER HIGHLIGHTS/THREATS...

A DEEP LOW/TROUGH WORKING GRADUALLY OVER THE WEST WILL SPREAD A
BROAD AREA OF RAIN AND HIGHER ELEVATION SNOWS FROM THE WEST COAST
INTO THE ROCKIES... WITH LEAD RAINS DEVELOPING OVER THE CENTRAL US
THIS WEEKEND INTO NEXT MONDAY. HIGHEST TOTALS ARE EXPECTED FROM
FAVORED SIERRA NEVADA AND INTERMOUNTAIN WEST TERRAIN INTO PORTIONS
OF CO/WY THEN OUT OVER THE PLAINS. SPC HAS A 15% RISK AREA OF
SEVERE STORMS ON SATURDAY AHEAD OF THE COLD FRONT FROM W TEXAS
NORTHWARD TO WESTERN KANSAS AND EASTERN COLORADO. TEMPERATURES
WITH THE SYSTEM ARE EXPECTED TO BE 10-15F BELOW AVERAGE UNDER THE
UPPER LOW. RIDGING ALOFT AHEAD OF THIS SYSTEM IS EXPECTED TO
SUPPORT LEAD WARMING SPREADING FROM THE CENTRAL/HIGH PLAINS FRIDAY
INTO THE SOUTHEAST BY SUNDAY AS THE COLD FRONT PUSHES THROUGH THE
MID-ATLANTIC.

EAST COAST/WESTERN ATLANTIC SURFACE LOWS/FRONTS WILL GENERALLY
SUPPORT COOL AND UNSETTLED WEATHER OVER THE EAST FRIDAY INTO
SATURDAY AHEAD OF THE NEXT FRONT AND DEEEPENING SFC LOW SUNDAY.
MUCH OF THE PRECIPITATION IS EXPECTED OVER THE MID-ATLANTIC/NEW
ENGLAND STATES FRIDAY-SUNDAY WITH WRAP-AROUND LIGHER PRECIP FOR
NEXT MONDAY IN NORTHERN NEW ENGLAND BUT CLEARING TO THE SOUTH.


FRACASSO/ROTH

$$





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