Quantitative Precipitation Forecast
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FOUS30 KWBC 140820
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
319 AM EST TUE NOV 14 2017

...VALID 12Z TUE NOV 14 2017 - 12Z WED NOV 15 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
75 WNW UIL 50 WNW UIL 30 N UIL 10 WSW CWSP 15 SSE CWSP 10 W CLM
10 WSW CLM 15 SW CLM 20 SW CLM 30 SSW CLM 35 SSW CLM 30 NW SHN
15 NW SHN 10 W SHN 20 SW SHN 30 NNE AST 10 SSE AST 20 NNW S47
30 W S47 65 W S47.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
55 ESE FLL 20 ESE MIA OPF 20 W KLNA 20 SW FPR 15 W MLB
10 SW TIX 10 NNW TTS 45 NE TTS.


OLYMPIC PENINSULA SOUTHWARD INTO FAR NORTHERN OREGON COAST RANGE

IN THE WAKE OF THE LEAD AREA OF HEIGHT FALLS THAT EJECTED OUT OF
THE MEAN TROF POSITION OFF THE PACIFIC NORTHWEST COAST AND INLAND
THROUGH THE PACIFIC NORTHWEST ON MONDAY---ADDITIONAL UPSTREAM
HEIGHT FALLS WILL RE-AMPLIFY THE MEAN CLOSED LOW POSITION OFF THE
SW COAST OF BRITISH COLUMBIA/VANCOUVER ISLAND THIS UPCOMING
PERIOD.  THE AMPLIFICATION WILL HELP FOCUS STRENGTHENING SOUTH
SOUTHWESTERLY LOW LEVEL FLOW INTO THE PACIFIC NORTHWEST.  PW
VALUES IN THIS ONSHORE FLOW AXIS ARE NOT EXPECTED TO BE
ANOMALOUS---GENERAL AT OR SLIGHTLY BELOW SEASONAL NORMS.
HOWEVER---AS THE CLOSED LOW AMPLIFIES---THE LOW LEVEL INFLOW WILL
REMAIN FOCUSED INTO PORTIONS OF THE PACIFIC NORTHWEST FROM THE
NORTHERN OREGON COAST RANGE---NORTHWARD INTO THE OLYMPIC RANGE AND
INTO THE NORTHERN WASHINGTON CASCADES.  THIS WILL SUPPORT
POTENTIAL FOR VERY HEAVY PRECIPITATION AMOUNTS ACROSS THESE
AREAS---ESPECIALLY INTO THE OLYMPIC RANGE WHICH WILL HAVE THE
GREATEST UPSLOPE ENHANCEMENT TO THE UVVS.  MAX PRECIP AMOUNTS IN
THE 5-8"+ RANGE POSSIBLE IN THE OLYMPIC RANGE--2 TO 4"+ SOUTH OF
THIS INTO THE NORTHERN OREGON COAST RANGE.  HOURLY RAINFALL RATES
ARE FORECAST TO REACH THE .25-50"+ RANGE LATE AFTERNOON INTO
TUESDAY NIGHT/EARLY WED MORNING FROM THE OLYMPIC RANGE SOUTH TO
THE NORTHERN OREGON COAST RANGE.  ACROSS THESE AREAS---RUNOFF
ISSUES MAY DEVELOP WITH A MARGINAL RISK AREA MAINTAINED IN THE DAY
1 EXCESSIVE RAINFALL POTENTIAL OUTLOOK.

EAST CENTRAL COAST OF FLORIDA

A MARGINAL RISK AREA WAS ADDED FOR THE UPCOMING DAY 1 PERIOD ALONG
THE EAST CENTRAL FLORIDA COAST FOR THE POTENTIAL OF FOCUSED EAST
TO WEST RAIN BANDS.  THE LATEST HI RES GUIDANCE IS MUCH MORE
EMPHATIC ABOUT HEAVY RAIN POTENTIAL FOR THIS PERIOD ACROSS THE
EAST CENTRAL COASTAL AREAS OF FLORIDA.  SIMILAR TO PREVIOUS
DAYS---LOW LEVEL EASTERLY FLOW IS EXPECTED TO PERSIST---BUT WITH
STRENGTHENING OF THIS EASTERLY FLOW EXPECTED THIS PERIOD.  THIS IS
RESULTING IN STRONGER BOUNDARY LAYER CONVERGENCE ALONG THE EAST
CENTRAL COASTAL AREAS THAN IN PAST DAYS---LEADING TO THE POTENTIAL
FOR FOCUSED EAST TO WEST ORIENTED RAIN BANDS IMPACTING THIS
REGION.  LOCALLY HEAVY RAINS HAVE OCCURRED OVER THE PAST SEVERAL
DAYS ACROSS THE EAST CENTRAL COAST OF FLORIDA---WITH THIS
POTENTIAL AGAIN OCCURRING THIS PERIOD.  THE LATEST HI RES GUIDANCE
IS SHOWING  MAX TOTALS IN THE 3-5"+ WHICH SEEM REASONABLE GIVEN
WHAT HAS OCCURRED OVER THE PAST 24 HOURS OVER MARTIN COUNTY.  NOT
A LOT OF CONFIDENCE WITH DETAILS---BUT GREATER CONFIDENCE ON THE
POTENTIAL FOR VERY HEAVY TO ISOLATED EXCESSIVE AMOUNTS WHERE THESE
BANDS SET UP---ESPECIALLY IN URBANIZED REGIONS.

ORAVEC

$$




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