Hail in Montana, May 20, 2004

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
901 AM MDT THU MAY 20 2004

.UPDATE...FORECASTS LOOK ON TRACK. IT APPEARS THE MAIN CONVECTIVE
FOCUS SHOULD BE ALONG A SURFACE AND UPPER LEVEL BOUNDARY.  THIS
BOUNDARY IS CURRENTLY FROM LOWELL TO MISSOULA AND DRUMMOND AND
SHIFTING VERY SLOWLY NORTHWARD.  HOWEVER...OTHER AREAS WILL ALSO BE
PRONE TO SEE SIGNIFICANT CONVECTION...ESPECIALLY WITH MORE HEATING
AND UNSTABLE CONDITIONS. WEDNESDAYS CONVECTION PRODUCED UP TO A HALF
INCH OF RAIN IN LESS THAN ONE HOUR.  SO...GIVEN THE ATMOSPHERE IS AS
MOIST AS WEDNESDAY AND LIKELY MORE UNSTABLE AND MORE HEATING
TODAY...BRIEF HEAVY RAIN IS POSSIBLE WITH ANY OF THE STORMS.
THESE RAIN FALL RATES MAY BE ENOUGH TO PRODUCE SIGNIFICANT
RUNOFF...FLASH FLOODING OR DEBRIS FLOWS ON 2003 SEVERE BURN AREAS...
THATS IF...THE STORM HITS THE BURN AREA.  HOWEVER...THE OVERALL
EXPECTED STORM COVERAGE AND UNCERTAINTY IN THE EXACT POSITION OF ANY
ONE STORM DICTATES ONLY CLOSE MONITORING AT THIS POINT.  IF
CONDITIONS BECOME FAVORABLE FOR HEAVY RAINS THAT COULD PRODUCE FLASH
FLOODING...A FLASH FLOOD WATCH WILL BE ISSUED.  A FLASH FLOOD WARNING
WILL BE ISSUED IF LIFE AND PROPERTY THREATENING FLOODING RAINS ARE
OBSERVED OR IMMINENT...JUST A LITTLE REMINDER OF THE WATCH/WARNING
CRITERIA...SINCE THERE IS A LOW TO MODERATE POTENTIAL TODAY...MAINLY
2003 SEVERE BURN AREAS.

&&

.PREVIOUS DISCUSSION...TODAY THROUGH SATURDAY...CURRENT
FORECAST LOOKED PRETTY GOOD. THERE WILL BE A BIT MORE SUNSHINE TODAY
THAN YESTERDAY AND ALLOW TEMPERATURES TO INCREASE SLIGHTLY TO NEAR
NORMAL READINGS. THE BIG CONCERN OF THE DAY WILL BE THUNDERSTORM
ACTIVITY...ESPECIALLY IN NORTHERN MONTANA AND THE CLEARWATER MOUNTAIN
REGION...WHERE PROBABILITY OF SHOWERS AND THUNDERSTORMS HAS BEEN
INCREASED IN MANY AREAS TO NUMEROUS...ESPECIALLY LATER IN THE
AFTERNOON AND EVENING...AS ANOTHER SHORT WAVE MOVES DOWN THE LONG
WAVE TROUGH FROM BRITISH COLUMBIA INTO NORTHERN MONTANA BY LATE
AFTERNOON INTO THE EVENING HOURS. THIS INCREASED INSTABILITY...
MOISTURE ALREADY IN PLACE AND SOLAR HEATING WILL ALLOW FOR SHOWER AND
THUNDERSTORM ACTIVITY...ESPECIALLY IN NORTHERN MONTANA. THUNDERSTORMS
ON WEDNESDAY DID PRODUCE LOCAL HEAVY DOWNPOURS OF RAIN AND GUSTY
DOWNBURST WINDS TO 25-30 MPH AT TIMES ALONG WITH ONE STORM PRODUCING
HALF INCH HAIL. CONVECTIVE PARAMETERS LOOK A LITTLE BIT STRONGER FOR
THIS AFTERNOON AND THIS EVENING WITH THIS NEXT SHORT WAVE MOVING INTO
THE REGION. THE QUESTION IS WILL THERE BE ENOUGH SOLAR HEATING TO
TRIGGER POTENTIALLY STRONG STORMS. THE CURRENT THOUGHT NOW IS IT IS A
POSSIBILITY FOR STORMS WITH HEAVY RAIN WHICH COULD POSE A THREAT IF
EVERYTHING LINES UP RIGHT TO THE 2003 BURN AREAS.

NOT MUCH CHANGE WITH THE FRIDAY AND SATURDAY OUTLOOK AS ANOTHER SHORT
WAVE MOVES THROUGH FROM BRITISH COLUMBIA ON FRIDAY AND BECOMING MORE
OF A CLOSED LOW SYSTEM ON SATURDAY. THIS CLOSED LOW WILL LOWER
TEMPERATURES ABOUT 5-10 DEGREES AND SNOW LEVELS REGION WIDE A FEW
THOUSAND FEET AND PROVIDE FOR A CONTINUING WET OUTLOOK.

SATURDAY NIGHT THROUGH WEDNESDAY...COOL UPPER LEVEL LOW PRESSURE
SYSTEM WILL DOMINATE THROUGH TUESDAY. THIS WILL KEEP TEMPERATURES ON
THE COOL SIDE AND PRECIPITATION GOING. SUNDAY NIGHT THE UPPER TROUGH
WILL DIG FORMING A CUTOFF LOW OFF THE COAST OF CENTRAL CALIFORNIA.
BEYOND TUESDAY SOME DISCREPANCIES IN THE MODELS ARE EVIDENT. GIVEN
THE ACTIVE PATTERN AND THE LINGERING CUTOFF LOW HAVE OPTED TO KEEP A
CHANCE OF PRECIPITATION IN THE FORECAST AND CONTINUE THE SLOW WARMING
TREND.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&

UPDATE/BAUCK
PREVIOUS DISCUSSION/RPN/GILCHRIST

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MISSOULA MT
135 PM MDT (1235 PM PDT) THU MAY 20 2004

MTZ002-004>006-211200-
WEST GLACIER REGION-LOWER CLARK FORK REGION-
MISSOULA/BITTERROOT VALLEYS-BITTERROOT/SAPPHIRE MOUNTAINS-
135 PM MDT THU MAY 20 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL IDAHO AND WESTERN
MONTANA

.DAY ONE... TODAY

A FLASH FLASH FLOOD WATCH HAS BEEN ISSUED FOR THE 2003 SEVERE BURN
AREAS WITHIN FLATHEAD...MISSOULA...MINERAL...AND NORTHERN RAVALLI
COUNTIES UNTIL 9 PM TONIGHT.

SCATTERED THUNDERSTORMS WITH LOCAL AREAS OF BRIEF HEAVY RAIN CAN BE
EXPECTED INTO THIS EVENING. THERE IS A SIGNIFICANT POTENTIAL FOR ONE
OR MORE OF THESE STORMS TO PRODUCE RAINFALL RATES THAT WILL CAUSE
FLASH FLOODING AND DEBRIS FLOWS IN THE FOLLOWING FOREST FIRE BURN
AREAS.

...LYON GULCH AND OBRIEN CREEK...
...DEER CREEK IN THE FISH CREEK DRAINAGE...
...EDS CREEK IN THE PETTY CREEK DRAINAGE...
...EIGHTMILE CREEK NEAR FLORENCE...
...SCHWARTZ CREEK NEAR CLINTON...
...FISH CREEK IN GLACIER NATIONAL PARK...
...CREEKS ON THE WEST SIDE OF HUNGRY HORSE RESERVOIR...

A FLASH FLOOD WATCH MEANS THAT FLASH FLOODING IS POSSIBLE ON BURN
AREAS WITHIN THE WATCH AREA. PEOPLE IN THE WATCH AREA ARE ADVISED TO
BE READY FOR QUICK ACTION AND BE PREPARED TO MOVE TO HIGHER GROUND IF
FLASH FLOODING THREATENS.

.DAYS TWO THROUGH SEVEN... FRIDAY THROUGH WEDNESDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

IDZ005>010-MTZ001-003-007-043-211200-
NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS-
OROFINO/GRANGEVILLE REGION-LOWER HELLS CANYON/SALMON RIVER-
WESTERN LEMHI COUNTY-EASTERN LEMHI COUNTY-KOOTENAI/CABINET REGION-
FLATHEAD/MISSION VALLEYS-BUTTE/PINTLAR REGION-BLACKFOOT REGION-
135 PM MDT (1235 PM PDT) THU MAY 20 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL IDAHO AND WESTERN
MONTANA

.DAY ONE... TODAY

A MOIST SYSTEM OVER OUR AREA IS EXPECTED TO PRODUCE SCATTERED SHOWERS
AND THUNDERSTORMS INTO THE EVENING HOURS...SHOWERS POSSIBLY HEAVY AT
TIMES.

THE MAIN CONCERN WOULD BE FOR PONDING AND POSSIBLY FLASH FLOODING...
SMALL DEBRIS/MUD FLOWS IN STEEP CANYONS

.DAYS TWO THROUGH SEVEN... FRIDAY THROUGH WEDNESDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.