Strong Wind in Washington, May 14, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
450 AM PDT SAT MAY 14 2011

.SYNOPSIS...
SOUTHERLY FLOW OVER THE INLAND NORTHWEST WILL RESULT IN WARM
TEMPERATURES AND PLENTY OF MOISTURE MOVING INTO THE AREA TODAY.
SHOWERY AND UNSETTLED WEATHER CAN BE EXPECTED TODAY THROUGH
MONDAY. THERE WILL BE THE POTENTIAL FOR HEAVY RAIN NEAR THE
CASCADES TODAY AND TONIGHT AND ACROSS THE EASTERN ZONE SUNDAY AND
MONDAY. MODERATE TO HEAVY RAIN AND WARM TEMPERATURES WILL RESULT
IN SHARP RISES ON MOST RIVERS AND STREAMS. STRONG THUNDERSTORMS
WILL BE POSSIBLE TODAY AND THIS EVENING. A COOL...SHOWERY WEATHER
REGIME WILL RETURN FOR NEXT WEEK.

&&

.DISCUSSION...
TODAY THROUGH SUNDAY EVENING...THE MAIN UPPER LEVEL LOW CONTINUES
TO SAG SOUTH OFF THE WEST COAST...MUCH AS THE MODELS HAD FORECAST.
A STRONG SHORT WAVE IS JUST ROUNDING THE BOTTOM OF THE TROUGH THIS
MORNING. THE RESULT ARE THE UPPER FLOW EAST OF THE CASCADES IS
BACKING TO SOUTHERLY THIS MORNING. AS THE SHORT WAVE ROUNDS THE
BOTTOM THE UPPER TROUGH WILL TAKE ON MORE OF A NEGATIVE TILT
TODAY THROUGH SUNDAY...EVENTUALLY ALLOWING A COLD FRONT TO MOVE
FROM SOUTHWEST TO NORTHEAST THROUGH THE FORECAST AREA LATE SUNDAY
AFTERNOON. THIS STORM SYSTEM HAS TAPPED INTO A VERY WET MOISTURE
SOURCE FROM OFF THE PACIFIC AND WILL BRING AREAS OF RAIN TO ALL
LOCATIONS. THE GRADIENT ACROSS THE AREA IS EASTERLY AND WE EXPECT A
LONG DURATION RAIN EPISODE FOR THE EAST SLOPES OF THE CASCADES AND
MODERATE TO HEAVY RAIN FROM THIS MORNING THROUGH EARLY SUNDAY
MORNING...THEN TRANSITIONING TO THE SOUTHEAST AND NORTHEAST AS THE
COLD FRONT MOVES THROUGH THE REGION ON SUNDAY. AREA RIVERS AND
STREAMS ARE ALREADY RUNNING HIGH DUE TO WARM TEMPERATURES AND
RAPID SNOWMELT. THIS WILL ONLY ADD TO THE SITUATION. RIVERS AND
STREAMS ARE BEING CLOSELY MONITORED AND NUMEROUS HYDROLOGIC
HIGHLIGHTS ARE ALREADY IN PLACE. PEOPLE LIVING NEAR STREAMS AND
RIVERS SHOULD MONITOR FLOWS CAREFULLY THROUGH NEXT WEEK.

THE NEXT WEATHER CHALLENGE WILL BE CONVECTION THIS MORNING THROUGH
THIS EVENING. VERY WARM AND VERY MOIST AIR IS MOVING INTO THE
REGION FROM THE SOUTH...FOLLOWING A VERY STRONG 850-700 THETA E
RIDGE. AT THIS TIME THE MAIN PUNCH OF MOISTURE IS MAINLY ACROSS MY
CENTRAL AND WESTERN ZONES..BUT THIS SHOULD MOVE A LITTLE FURTHER
NORTH AND EAST LATER THIS MORNING. IN ADDITION THE MID AND UPPER
LEVEL ATMOSPHERE IS VERY UNSTABLE AND WITH A COUPLE OF WEAK SHORT
WAVES ACTING AS FORCING MECHANISMS WE ARE GETTING SOME ISOLATED TO
SCATTERED THUNDERSTORMS MAINLY EAST OF A LINE FROM WALLA WALLA TO
COULEE CITY EARLY THIS MORNING. BECAUSE THIS IS ELEVATED
CONVECTION WE EXPECT THESE TO LINGER THROUGH THE NIGHT BEFORE
DISSIPATING SOON AFTER SUNRISE.

THE FOCUS THEN TURNS TO AFTERNOON SURFACE BASED CONVECTION LATER
THIS MORNING AND THIS AFTERNOON. INSTABILITY PARAMETERS ARE
PRETTY HIGH...CAPES 700-1300J/KG AND LI'S -3 TO -5 AND PLENTY OF
MOISTURE. THERE WILL BE ENOUGH 0-6KM SHEAR FOR THE POTENTIAL FOR
A FEW OF THESE STORMS TO CONTAIN SEVERE HAIL...OTHERWISE EXPECT
LOCALLY HEAVY RAIN AND GUSTY WINDS. ALSO WE WILL HAVE SOME WEAK
LIFTING MECHANISMS IN THE FORM OF A FEW RIPPLING WAVES MOVING
THROUGH THE AREA. THIS ALL WILL COMBINE FOR A PRETTY ACTIVE
AFTERNOON AND EVENING FOR THUNDERSTORMS.

IF THAT ISN'T ENOUGH THE EASTERLY GRADIENT IS ALREADY BEGINNING TO
TIGHTEN ACROSS MY NORTHERN AND EASTERN IN RESPONSE TO THE
DEEPENING LOW PRESSURE SYSTEM OFF THE COAST. THE GRADIENT BETWEEN
KALISPELL AND SPOKANE IS 10MB WITH EASTERLY WINDS ACROSS THE
EASTERN ZONES 10-15 MPH WITH GUSTS ABOVE 20-25 MPH. WINDS SHOULD
INCREASE A LITTLE MORE THROUGH THE MORNING BEFORE DISSIPATING A
LITTLE THIS AFTERNOON. WITH THE APPROACHING COLD FRONT TONIGHT
EXPECT THE EASTERLY WINDS TO BE ON THE INCREASE AGAIN THIS
EVENING. TEMPERATURES WILL REMAIN ON THE MILD SIDE TODAY THROUGH
SUNDAY. /TOBIN

SUNDAY NIGHT THROUGH TUESDAY...MOISTURE AND SHORTWAVE ENERGY
PIVOTING AROUND THE UPPER LEVEL LOW WILL PUSH THE FOCUS FOR
PRECIPITATION TO THE NORTHEAST ZONES SUNDAY NIGHT AND THEN ACROSS
THE NORTHERN TIER MONDAY. PERIODS OF HEAVY RAIN WILL BE POSSIBLE
OVERNIGHT SUNDAY INTO MONDAY MORNING. RAINFALL INTENSITY WILL
DIMINISH BY MONDAY NIGHT AS THE UPPER LOW STARTS TO SHEAR APART WITH
MUCH OF THE ENERGY SLIDING SOUTH INTO THE GREAT BASIN OR TO OUR
NORTH INTO SOUTHERN BRITISH COLUMBIA. THE SURFACE LOW IN BC WILL
DEEPEN MONDAY...INCREASING SOUTHERLY GRADIENT WINDS. EXPECT BREEZY
TO WINDY CONDITIONS ACROSS THE BASIN AND INTO THE NORTH-SOUTH
ORIENTED VALLEYS ACROSS THE NORTH DURING THE AFTERNOON AND EVENING
HOURS. WINDS WILL SLACKEN OVERNIGHT. TEMPERATURES WILL BE ABOUT 10
DEGREES BELOW SEASONAL NORMALS...WHICH WILL MITIGATE SOME OF THE
FLOODING PROBLEMS. MODELS ARE IN GENERAL AGREEMENT WITH ADDITIONAL
RAINFALL THROUGH MONDAY NIGHT RANGING FROM AROUND A HALF TO THREE
QUARTERS OF AN INCH FOR THE CENTRAL PANHANDLE AND THE NORTHERN
MOUNTAINS. THE LOWER ELEVATIONS WILL SEE AROUND A TENTH TO A QUARTER
INCH WITH LOWER AMOUNTS FOR THE BASIN. A FEW AFTERNOON THUNDERSTORMS
WILL BE POSSIBLE MONDAY AND AGAIN TUESDAY BUT CONVECTIVE CONDITIONS
DO NOT APPEAR TO SUPPORT STRONG STORMS.

WEDNESDAY THROUGH FRIDAY...THE BLOCKING PATTERN WILL START TO BREAK
DOWN AS THE UPPER LOW WORKS TO UNDERCUT THE RIDGE OVER THE CENTRAL
PLAINS AND CANADIAN PRAIRIES. AS THE LOW MOVES OUT OF THE AREA...
MOISTURE WILL RETREAT AND SHOWERS WILL DIMINISH. A BRIEF RIDGE WILL
BUILD OVER THE REGION BY THURSDAY WITH MAINLY DRY CONDITIONS FOR THE
END OF THE WORK WEEK. THIS WILL GIVE AREA RIVERS THE OPPORTUNITY TO
RECEDE SOMEWHAT BUT TEMPERATURES WILL BE ON A WARMING TREND...KEEPING
THE SNOWMELT TAP OPEN. THE MORE PROGRESSIVE FLOW THAT ALLOWS THE
RIDGE TO MOVE INTO THE REGION WILL ALSO BRING ANOTHER TROUGH OF LOW
PRESSURE JUST IN TIME FOR THE WEEKEND. /KELCH

&&

.AVIATION...
12Z TAFS...ELEVATED SHOWERS AND THUNDERSTORMS WILL REMAIN ACTIVE
FROM THE BLUE MOUNTAINS NORTHWEST TO THE CASCADES THIS MORNING.
EXPECT THESE STORMS TO BE ON THE DECREASE SOON AFTER SUNRISE AS THE
ATMOSPHERE SWITCHES FROM ELEVATED CONVECTION TO SURFACED BASED
CONVECTION THIS LATE THIS MORNING THROUGH THIS AFTERNOON. WHILE ALL
TAF SITES WILL HAVE THE CHANCE FOR AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS THE FOCUS APPEARS TO AGAIN BE FROM THE BLUES ACROSS
THE LOWER BASIN AND NORTHWEST TO THE CASCADE. FROM THE DEEP BASIN
WESTWARD EXPECT INTERMITTENT HEAVY SHOWERS THROUGH 12Z SUNDAY WITH
CIGS/VSBY DROPPING TO MVFR DURING THE HEAVIEST SHOWERS. THIS SAME
AREA WILL HAVE THE BEST CHANCE FOR THUNDERSTORMS THROUGH 06Z AS
WELL. THE THUNDERSTORMS MAY CONTAIN HEAVY RAIN...LARGE HAIL AND
GUSTY/ERRATIC WINDS. A TIGHT NE-E PRESSURE GRADIENT WILL INCREASE
WIND SPEEDS TO 10-20KT WINDS WITH GUSTS 20-25KT POSSIBLE. THIS
GRADIENT IS EXPECTED TO RELAX LATER THIS AFTERNOON...WITH WINDS
DECREASING TO AROUND 10KTS OR LESS. /TOBIN

&&

.PRELIMINARY POINT TEMPS/POPS...
SPOKANE        73  47  57  40  53  36 /  40  50 100 100  80  50
COEUR D'ALENE  73  45  61  42  52  35 /  30  30 100 100  90  60
PULLMAN        75  49  57  40  53  35 /  60  70 100 100  70  50
LEWISTON       78  52  61  44  58  40 /  70  70 100 100  70  50
COLVILLE       75  46  67  45  56  37 /  30  40  80 100 100  70
SANDPOINT      70  42  66  40  52  35 /  10  10  90 100 100  60
KELLOGG        69  41  62  38  49  35 /  20  20 100 100 100  50
MOSES LAKE     76  52  60  40  60  36 / 100 100 100  70  40  40
WENATCHEE      73  51  60  43  59  40 / 100 100 100  80  30  30
OMAK           76  50  63  43  59  36 /  80  80 100  90  80  50

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
WA...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SPOKANE WA
550 AM PDT SAT MAY 14 2011

IDZ001>004-026-027-WAZ031>038-041>044-151300-
NORTHERN PANHANDLE-COEUR D'ALENE AREA-IDAHO PALOUSE-
CENTRAL PANHANDLE MOUNTAINS-LEWISTON AREA-
LEWIS AND SOUTHERN NEZ PERCE COUNTIES-NORTHEAST BLUE MOUNTAINS-
LOWER GARFIELD AND ASOTIN COUNTIES-WASHINGTON PALOUSE-
MOSES LAKE AREA-UPPER COLUMBIA BASIN-SPOKANE AREA-
NORTHEAST MOUNTAINS-OKANOGAN HIGHLANDS-WENATCHEE AREA-
EAST SLOPES NORTHERN CASCADES-OKANOGAN VALLEY-WATERVILLE PLATEAU-
550 AM PDT SAT MAY 14 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH IDAHO...
NORTH CENTRAL IDAHO...CENTRAL WASHINGTON...EAST CENTRAL
WASHINGTON...NORTH CENTRAL WASHINGTON...NORTHEAST WASHINGTON AND
SOUTHEAST WASHINGTON.

.DAY ONE...TODAY AND TONIGHT

STRONG THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON AND THIS
EVENING OVER SOUTHEAST WASHINGTON AND PORTIONS OF THE SOUTHERN
IDAHO PANHANDLE. LARGE HAIL AND DAMAGING WIND GUSTS WILL BE A
POSSIBLE IN THE LEWISTON...POMEROY...PULLMAN...KAMIAH AREAS AND
WEST INTO THE COLUMBIA BASIN.

RAPID MOUNTAIN SNOW MELT WILL BRING INCREASING AMOUNTS OF WATER
INTO MANY RIVER SYSTEMS TODAY AND TONIGHT. PLEASE REFERENCE
CURRENT FLOOD WATCHES AND WARNINGS IN EFFECT FOR MORE DETAILS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

SEVERAL ROUNDS OF RAIN ARE EXPECTED SUNDAY THROUGH MONDAY. THE
COMBINATION OF RAIN AND MELTING SNOW WILL HEIGHTEN THE POTENTIAL
FOR FLOODING IN THE MOUNTAINOUS ZONES OF EASTERN WASHINGTON AND
NORTH IDAHO. RIVERS WILL LIKELY RUN HIGH THROUGH THE MIDDLE OF
NEXT WEEK.