Quantitative Precipitation Forecast
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000
FOUS30 KWBC 190100
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
859 PM EDT SAT MAR 18 2017

...VALID 01Z SUN MAR 19 2017 - 12Z SUN MAR 19 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 SE MLP 25 NE P69 35 SE P69 40 S P69 30 ENE MYL 35 ESE MYL
25 WNW SNT 40 NNE BOI MYL 25 NNW MYL 40 WSW P69 30 NW P69
35 SW MLP MLP 15 SSE MLP 45 SE MLP.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
65 NE MSO 20 ENE MSO 30 SSE GPI 15 NNW GPI 40 NNW GPI
35 SSW CWRT 25 WSW 8S0 65 NE MSO.


01 UTC UPDATE...

MAINTAINED TWO TOPOGRAPHICALLY FOCUSED MARGINAL THREAT AREAS OVER
N-CENTRAL ID AND NWRN MT...BUT ADJUSTED EARLIER WPC GUIDANCE TO
BETTER MATCH LATEST RADAR AND HRRR TRENDS AS THE SUPPORTING
FEATURES TRANSLATE INLAND.

SCHICHTEL


...IDAHO / EASTERN WASHINGTON / NORTHWEST MONTANA...

A DEEP LAYER...FULL LATITUDE TROUGH WILL CONTINUE TO MIGRATE
INLAND EARLY TODAY...THEN SHEAR CONSIDERABLY DURING THE LATTER
HALF OF THE PERIOD (00-12Z SUN) AS IT IMPINGES ON THE
HIGHLY-AMPLIFIED DOWNSTREAM RIDGE. AS THE TROUGH EVOLVES TOWARD A
FLATTER...MORE NORTHERN-STREAM DOMINANT SYSTEM...THE EMPHASIS FOR
DEEPER LIFTING (ENHANCED BY RIGHT ENTRANCE REGION UPPER JET
FORCING/FRONTOGENESIS) AND MOISTURE TRANSPORT WILL BE CONFINED TO
THE NORTHERN STREAM...AFFECTING THE NORTHERN INTERMOUNTAIN WEST
AND NORTHERN ROCKIES. THIS PORTION OF THE TROUGH WILL BRING STRONG
SOUTHWESTERLY PRE-FRONTAL FLOW AND MODESTLY ANOMALOUS MOISTURE
FLUX...AS PRECIPITABLE WATER VALUES RISE TO NEAR 0.75 INCHES
ACROSS NORTHERN IDAHO AND ADJACENT PARTS OF WA/OR...WITH PW VALUES
ABOVE 0.50 INCHES INTO MONTANA.

EXPECT OROGRAPHICALLY ENHANCED MOD-HEAVY RAIN...THE BULK OF IT
OCCURRING UNDERNEATH THE BROAD WARM CONVEYOR BELT AS THE
DEEP-LAYER FRONTOGENESIS INCREASES AND PRE-FRONTAL MOISTURE
ANOMALIES REMAIN HIGH (+3-3.5 STANDARD DEVIATIONS PER THE
SREF/GEFS). AREAL-AVERAGE TOTALS OF 1-2" OF LIQUID EQUIVALENT
PRECIPITATION ARE ANTICIPATED OVER THE HIGHER TERRAIN IN
CENTRAL-NORTHERN ID INTO NORTHWEST MT...THE BULK OF WHICH IS
EXPECTED TO FALL IN A 12-18 HOUR PERIOD. SOILS REMAIN UNUSUALLY
SATURATED THROUGHOUT THIS REGION OWING TO SNOW MELT AND CONTINUED
ADDITIONAL RAINFALL. WHILE THE ODDS OF EXCEEDING THE STATIC FLASH
FLOOD GUIDANCE VALUES ARE NOT HIGH...RAIN RATES APPROACHING OR
EXCEEDING A HALF INCH IN THREE HOURS MAY CONTRIBUTE TO LOCALIZED
RAPID SURFACE RUNOFF.

BURKE/HURLEY
$$





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