609
FXUS66 KOTX 221805
AFDOTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPOKANE WA
1105 AM PDT MON JUL 22 2019
SYNOPSIS
MUCH WARMER WEATHER WILL ARRIVE TODAY AND TUESDAY WITH
WIDESPREAD HIGHS IN THE UPPER 80S AND 90S. THE POSSIBILITY OF
HIGH BASED THUNDERSTORMS WILL ALSO DEVELOP DURING THIS HOT PERIOD
ESPECIALLY TUESDAY NIGHT. A COLD FRONT PASSAGE WILL MODERATE
TEMPERATURES BACK TO NEAR NORMAL WEDNESDAY, BUT WILL BRING WITH
IT BREEZY WINDS. DRY AND SEASONABLY WARM CONDITIONS ARE EXPECTED
FOR THE END OF THE WORK WEEK.
DISCUSSION
TODAY: VERY TRICKY AND DIFFICULT FORECAST FOR THE NEXT 36 HOURS.
SOME ELEVATED SHOWERS HAVE BEEN MOVING UP OVERNIGHT FROM EASTERN
OREGON. THEY ARE ALREADY INTO THE LC VALLEY AND CAMAS PRAIRIE.
HAVE NOT BEEN ABLE FIND ANY PRECIP REACHING THE GROUND YET IN OUR
FORECAST AREA. LIGHTNING HAS WANED OVERNIGHT, BUT THE NAM IS
SHOWING AFT 5AM SOME STRONGER ELEVATED CAPE MOVING INTO THE
AFOREMENTIONED AREA. SO HAVE KEPT OUR THREAT OF THUNDER THROUGH
THE MORNING HOURS. THEN IN THE AFTERNOON THE CHANCE OF SHOWERS AND
THUNDERSTORMS EXPANDS ACROSS MUCH OF EASTERN WA AND N ID, AS WELL
AS ALONG THE CANADIAN BORDER OF THE NORTHERN CASCADES AND
OKANOGAN VALLEY. WE ARE EXPECTING SOME MODERATELY DENSE MID AND
HIGH LEVEL CLOUDS THIS MORNING INTO THE EARLY AFTERNOON. THIS
COULD HAMPER OUR DAYTIME HIGHS. THE MODELS SEEM TO THINK THE
THICKER CLOUDS WILL MOVE OUT OF THE AREA BY MID TO LATE AFTERNOON
AND WE WILL STILL SEE HIGH TEMPERATURES PROBABLY REACHED EARLY
THIS EVENING.
TONIGHT AND TUESDAY: THE THREAT OF THUNDERSTORMS WILL CONTINUE
THROUGH THE EVENING AND OVERNIGHT HOURS...AND THROUGH TUESDAY.
ONCE AGAIN, ELEVATED INSTABILITY WILL BE MOVING IN AND STRETCH
FROM THE BLUES INTO THE NORTH ID PANHANDLE. THEN ON TUESDAY THE
THREAT EXPANDS IN THE AFTERNOON INTO PORTIONS OF THE CASCADES AND
OKANOGAN VALLEY. THE MODELS HAD BEEN HINTING AT CONVECTION IN THE
CASCADES YESTERDAY AND TODAY THE CONFIDENCE CONTINUES TO GROW AND
EXPAND ACROSS THE AREA. TEMPERATURES WILL BE JUST A FEW DEGREES
WARMER, FOR POTENTIALLY THE WARMEST DAY WE HAVE SEEN THIS SUMMER
FOR MANY LOCATIONS. /NISBET
TUESDAY NIGHT AND WEDNESDAY: EVERYTHING COMES TOGETHER FOR AN ACTIVE WEATHER
EVENT ON TUESDAY NIGHT. THE HOT TEMPERATURES IN THE 90S, COMBINED WITH DEW
POINTS IN THE LOWER 50S, CREATE A RATHER UNSTABLE ATMOSPHERE ON TUESDAY
AFTERNOON. MEANWHILE A VERY STRONG NEGATIVE-TILT SHORT WAVE MOVES ONSHORE. THIS
IS AN EXCELLENT PATTERN FOR SEVERE WEATHER IN OUR AREA. HOWEVER, THE TIMING IS
NOT GOOD FOR SEVERE STORMS. THE SHORT WAVE MOVES THROUGH OUR AREA OVERNIGHT,
RATHER THAN DURING THE AFTERNOON. THIS LATER ARRIVAL TIME ALLOWS THE LOWER
ATMOSPHERE TO DECOUPLE, DECREASING THE INSTABILITY.
EVEN SO, THERE IS STILL A LARGE AMOUNT (500-1000 J/KG) OF ELEVATED CAPE, ALONG
WITH ABOUT 1 INCH OF PRECIPITABLE WATER. SO AS THIS SHORT WAVE SWINGS THROUGH
IN THE EVENING, THUNDERSTORMS ARE EXPECTED TO DEVELOP AROUND 5PM ALONG THE
WA/OR BORDER, SPREADING INTO THE UPPER COLUMBIA BASIN BY 8PM, AND THEN COVERING
MOST OF EASTERN WA AND THE IDAHO PANHANDLE BY MIDNIGHT. THE MAIN THREAT WILL BE
STRONG WIND GUSTS (FROM THE THUNDERSTORMS AND THE COLD FRONT) AND SMALL HAIL.
EXPECT BRIEF DOWNPOURS, BUT THE STORMS WILL BE MOVING TOO FAST TO CAUSE ANY
FLOODING CONCERNS. LIGHTNING COULD START SOME FIRES, AND THE GUSTY WINDS COULD
HELP SPREAD FIRES. BUT THE RAIN AND HIGH HUMIDITY SHOULD LIMIT THE NUMBER OF
FIRE STARTS AND SPREAD.
THE SYSTEM EXITS THE REGION QUICKLY BY WEDNESDAY MORNING, WITH JUST A FEW
MORNING SHOWERS OVER THE NORTHERN/EASTERN MOUNTAINS. TEMPERATURES WILL BE
ABOUT 15 DEGREES COOLER ON WEDNESDAY. RJ
WEDNESDAY NIGHT THROUGH SUNDAY...FROM MID WEEK ONWARD THERE IS
LOOSE MODEL AGREEMENT FEATURING A COUPLE DAYS OF WARMING UNDER A
FLAT RIDGE FOLLOWED BY A COLD FRONT PASSAGE ON OR ABOUT SATURDAY.
FOR THURSDAY AND FRIDAY A SURFACE THERMAL TROUGH WILL RE-
ESTABLISH ITSELF OVER THE COLUMBIA BASIN AS A SHORT WAVE RIDGE
POPS UP OVER THE AREA. THIS WILL ALLOW TEMPERATURES TO RISE BACK
INTO THE MID 80S ON THURSDAY AND PEAK IN THE UPPER 80S TO LOWER
90S ON FRIDAY WITH LIGHT WINDS AND ABUNDANT SUNSHINE. THE EXPECTED
ARRIVAL OF THE NEXT WEAK PACIFIC SHORT WAVE DISTURBANCE FRIDAY
NIGHT OR SATURDAY DOES NOT APPEAR TO BRING ANY APPRECIABLE
PRECIPITATION THREAT BUT MAY MANIFEST ITSELF AS A DRY AND BREEZY
PERIOD ON SATURDAY WITH TEMPERATURES COOLING BACK INTO THE MID 80S
OVER MOST LOCATIONS WITH THE REST OF THE UPCOMING WEEKEND
REMAINING DRY AND BENIGN WITH SEASONABLY NORMAL TEMPERATURES.
/FUGAZZI
AVIATION
18Z TAFS: SHOWERS EMBEDDED IN THE MID-LEVEL MOISTURE PLUME CONTINUE
TO MOVE NORTH AND NORTHEAST ACROSS EASTERN WA AND THE ID
PANHANDLE. SOME HIGH-BASED THUNDERSTORMS ARE STILL EXPECTED TO
DEVELOP AND MOVE NEAR MANY OF THE TAF LOCATIONS THIS AFTERNOON BUT
IT REMAINS UNCERTAIN AS TO PROXIMITY AND TIMING. THEREFORE, A
CLOSE WEATHER WATCH WILL BE MAINTAINED FOR THE TAF SITES IN THE
REGION COVERED WITH A VCTS. THE TAFS WILL BE UPDATED AS
THUNDERSTORMS MOVE NEARER TO THE AIRPORTS. THERE IS A CHANCE FOR
SOME SHOWERS TO DEVELOP NEAR MWH-EAT DURING THE EARLY MORNING
HOURS AFTER MIDNIGHT. OTHERWISE, VFR CONDITIONS WILL CONTINUE FOR
ALL TAF LOCATIONS THROUGH THE FORECAST PERIOD. /AKY
PRELIMINARY POINT TEMPS/POPS
SPOKANE 90 61 93 58 78 52 / 10 10 10 50 0 0
COEUR D'ALENE 89 60 93 58 76 52 / 20 10 20 60 10 0
PULLMAN 90 58 92 55 75 49 / 30 20 20 60 0 0
LEWISTON 97 68 99 65 84 58 / 20 20 10 50 0 0
COLVILLE 91 53 97 53 83 45 / 20 0 0 50 20 0
SANDPOINT 84 58 91 58 75 50 / 20 20 10 60 20 0
KELLOGG 88 63 92 61 73 54 / 20 20 20 60 10 0
MOSES LAKE 96 63 95 59 84 55 / 10 10 0 30 0 0
WENATCHEE 93 67 92 62 81 58 / 0 10 10 10 0 0
OMAK 93 63 95 61 83 56 / 10 0 10 50 10 0
OTX WATCHES/WARNINGS/ADVISORIES
ID...NONE.
WA...NONE.
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