Hail in Colorado, May 1, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PUEBLO CO
242 PM MDT TUE MAY 1 2007

.SHORT TERM...
(TONIGHT AND WEDNESDAY)

...RELATIVELY ACTIVE WEATHER PATTERN OVER THE NEXT 24 HOURS...
...POTENTIAL MODERATE WARM RAINFALL OVER SNOW PACK TONIGHT...

CURRENTLY...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES
SHOWED DIRTY RIDGE OVER SOUTHERN AND CENTRAL ROCKIES WITH MINOR
SHORTWAVES RIPPLING THROUGH THE WEAK FLOW. OLD CLOSED LOW WAS OVER
THE CENTRAL PLAINS. THE NEXT SYSTEM TO WATCH WAS ABOUT TO ENTIRE THE
DESERT SOUTHWEST. REGIONAL IR SATELLITE AND RADAR IMAGERY HAD
ISOLATED-NUMEROUS SHOWERS AND THUNDERSTORMS POPPING OVER THE
MOUNTAINS AND ADJACENT LOWER ELEVATIONS AROUND 1100 AM...WHICH IS
ON-TIME FOR SUMMERTIME CONVECTIVE PRECIPITATION. CELLS HAVE BEEN
NEARLY STATIONARY GIVEN THE WEAK STEERING FLOW ALOFT. AIR MASS
PRETTY MOIST CONSIDERING IT IS EARLY MAY. REGIONAL 12Z/01 SOUNDING
OBSERVATIONS HAD 150-200 PERCENT ABOVE NORMAL FOR PRECIPITABLE WATER
INDICES. NOW...THAT IS 0.50 TO 0.70 INCHES...BUT IT IS STILL
RELATIVELY MOIST FOR THIS TIME OF THE YEAR. SURFACE DEW POINTS ARE
NOT TOO BAD EITHER...WITH 20S/30S IN THE MOUNTAINS AND 40S/50S
ACROSS SOUTHEAST CO PLAINS.

TONIGHT...BIG CHALLENGE WITH WHAT WILL REALLY HAPPENED. MIDLEVEL
RIDGE IS KNOCKED DOWN OR SHIFTS EASTWARD WITH THE ADVANCING CLOSED
LOW OVER THE DESERT SOUTHWEST. THE LATE AFTERNOON AND EVENING WILL
CONTINUE TO HAVE ISOLATED - NUMEROUS SHOWERS AND THUNDERSTORMS OVER
MUCH OF SOUTH CENTRAL AND SOUTHEAST CO THANKS TO INSTABILITY...
MOISTURE...HEATING...AND WEAK DISTURBANCES. THE MAIN IMPACT WEATHER
WOULD BE HAIL UP TO 1/2 INCH IN DIAMETER...WIND GUSTS UP TO 45
MPH...MODERATE TO HEAVY RAIN...AND CLOUD TO GROUND LIGHTNING. AFTER
MIDNIGHT...THE CLOSED LOW MOVES THROUGH CENTRAL/SOUTHERN AZ/NM. MUCH
OF THE BETTER SYNOPTIC SCALE ASCENT WOULD BE FOCUSED FURTHER SOUTH
OF SOUTHERN CO. THERE IS HINTS OF WEAK MIDLEVEL ISENTROPIC ASCENT
AND THIS COMBINED WITH MOISTURE AND INSTABILITY IS PROBABLY SETTING
OFF CONVECTIVE BOMBS IN THE WRF AND GFS DATA. HARD TO SAY EXACTLY
WHERE THE PRECIPITATION SHIELD WILL FORM TONIGHT. MY GUT SAYS THE
SYNOPTIC SCALE ASCENT PRECIPITATION SHIELD...MESOSCALE CONVECTIVE
SYSTEM...WILL BE ACROSS NM AND THE REMNANTS WILL DISSIPATE AS IT
MIGRATES NORTHWARD INTO SOUTHERN CO. ACTUALLY...IT WOULDN/T BE
SURPRISED TO SEE THE RADAR NOT SHOWING MUCH ACTIVITY ACROSS SOUTHERN
CO AFTER MIDNIGHT. HOWEVER...THERE IS STILL THE POTENTIAL FOR STEADY
LIGHT TO MODERATE RAINFALL ACROSS THE MOUNTAINS/HIGH VALLEYS
TONIGHT. THIS BRINGS UP SOME IMPACT WEATHER/HYDRO ISSUES GIVEN
RELATIVELY WARM RAINFALL ON SNOW PACK POTENTIAL. THE BEST I CAN TELL
IS THE SNOW PACK LEVEL STARTS AROUND 8K TO 10K FT MSL. PROJECTED
FREEZING AND WET BULB ZERO HEIGHTS ARE PRETTY HIGHT...11K TO 14K FT
MSL...POSSIBLY LOWERING TO AROUND 10K FT MSL LATER TONIGHT. THUS...
THERE IS A POTENTIAL FOR WARM RAINFALL ON MELTING SNOW PACK DURING
THE NIGHT. DEL NORTE AT RIO GRANDE IS 2.5 FEET AWAY FROM FLOOD
STAGE...HOWEVER...THAT PART OF THE RIVER CAN HANDLE A LOT OF WATER.
WGRFC RAN A QUICK MODEL FOR 0.50 INCH OF WATER IN 12 HOURS WITH SNOW
MELT OVER THE BASIN...AND THE DEL NORTE ONLY INCREASED 1000 CFS...
WHICH FALLS SHORT OF BANKFUL. HOWEVER...1-2 INCH RAINFALL OVER A 12
HOUR PERIOD COULD CAUSE PROBLEMS IN LOCAL AREAS.  WILL HOLD OFF
ISSUING A FLOOD WATCH FOR RAIN ON SNOW PACK MELTING...BUT MENTION
HERE AND HAZARDOUS WEATHER OUTLOOK. MOUNTAIN PEAKS COULD SEE 1 TO 4
INCHES OF SNOWFALL TONIGHT AND THIS IS COVERED WELL IN THE DIGITAL
FORECAST DATABASE.

WEDNESDAY...CLOSED LOW CONTINUES MOVING EASTWARD ACROSS NM AND INTO
THE SOUTHERN PLAINS. RELATIVELY HIGH MOISTURE CONTENT CONTINUES
ACROSS THE CENTRAL ROCKIES WITH THE POTENTIAL FOR MORE SHOWERS AND
THUNDERSTORMS TO DEVELOP. MIDLEVEL FLOW IS RELATIVELY WEAK...SO
SHOWERS AND THUNDERSTORMS WILL BE MOVING SLOWLY. H7-H5 SPECIFIC
HUMIDITY VALUES AROUND 5 G/KG.  THE MAIN THUNDERSTORM IMPACT WEATHER
SHOULD BE MODERATE TO HEAVY RAIN...HAIL UP TO 1/2 INCH...WIND GUSTS
UP TO 45 MPH...AND CLOUD TO GROUND LIGHTNING. CONSIDERING THERE
SHOULD BE MORE CLOUDS AND THIS AFTERNOON/S TEMPERATURES BARELY GOT
INTO THE 70S...I HAVE COOLED OFF MAXIMUM TEMPERATURES FOR
WEDNESDAY. METZE

.LONG TERM...
(WEDNESDAY NIGHT THROUGH TUESDAY)

...UNSETTLED WEATHER THROUGH THE EXTENDED PERIOD...

TRICKY FORECAST FOR THE EXTENDED PERIOD AS A LONGWAVE TROUGH MOVES
INTO THE WESTERN HALF OF THE COUNTRY.

WED NIGHT...UPPER DISTURBANCE SLIDES ACROSS THE TX AND OK PANHANDLES
AND WEAKENS...WITH EASTERLY FLOW IN THE EVE STILL PRODUCING
CONVECTION FOR THE E PLAINS. ONGOING GRIDS HAD SCATTERED POPS FOR
THE PLAINS...ISOLATED ELSEWHERE AND SAW NO NEED TO ALTER THIS. MILD
TEMPS EXPECTED DUE TO EXTENSIVE CLOUD COVER FOR MUCH OF THE NIGHT.

THURSDAY AND FRIDAY...DIFFICULT DAYS HERE AS THE UPPER LOW DROPS
INTO THE PAC NW. MODELS INDICATE THAT DRIER AIR WILL GET ENTRAINED
IN THE UPPER FLOW ACROSS THE STATE...WITH MUCH OF THE CWA PERHAPS
STAYING DRY. ALSO...LATEST GUIDANCE POINTS TO THU AND FRI HAVING THE
HIGHEST MAX TEMPS THROUGH THE EXTENDED WHICH SEEMS REASONABLE SINCE
AT FIRST GLANCE MUCH OF THE CWA WILL BE IN A DOWNSLOPE SITUATION.
HOWEVER...LOT OF FACTORS TO JUGGLE. FIRST IS THE DRY LINE ALONG THE
CO/KS BORDER. CURRENTLY IT LOOKS AS IF IT WILL ONCE AGAIN RIDE THE
STATE LINE...BUT SOME WAVERING WEST OR EAST IS ALMOST ASSURED. CAPE
CHARTS INDICATE 1000 TO 1500 J/KG BY THU AFTN...ALONG WITH 40 TO 50
KTS BULK SHEAR. SO IF STORMS CAN GET GOING...SEVERE POTENTIAL IS
HIGH. THEN ON FRI...UPPER JET STARTS DIGGING AND SWINGING AROUND THE
SOUTHERN END OF THE TROUGH...ADDING FRONT LEFT QUAD DYNAMICS TO THE
EQUATION. THEREFORE...ADDED ISOLATED POPS MOST AREAS BOTH DAYS WHERE
IT WAS DRY...BUT DID NOT GO HIGHER JUST YET BECAUSE OF UNCERTAINTY.
NEXT CREW CAN ACT UPON THIS IF THERE IS RUN TO RUN CONTINUITY.

SATURDAY THROUGH TUESDAY...THE UPPER TROUGH SPLITS...WITH THE
SOUTHERNMOST UPPER LOW DROPPING DOWN ACROSS THE GREAT BASIN EARLY
SAT AND THEN STALL OUT OVER UT AND AZ THROUGH MON...THEN EJECT TO
THE N-NE ON TUE. MODELS ARE POINTING TO A GOOD AMOUNT OF PCPN OVER
AN EXTENDED PERIOD. ONGOING FORECAST HAS A DAILY MENTION OF SHOWERS
AND THUNDERSTORMS THROUGH THE END OF THE EXTENDED... AND THIS LOOKS
TO BE THE BEST SOLUTION AT THIS TIME SINCE ACTUAL AMOUNTS WILL BE
DICTATED BY WHERE THE LOW EVENTUALLY SETS UP. MOORE

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

17/27

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE PUEBLO CO
1151 AM MDT TUE MAY 1 2007

COZ058>089-093>099-021300-
WESTERN MOSQUITO RANGE/EAST LAKE COUNTY ABOVE 11000 FT-
LEADVILLE VICINITY/LAKE COUNTY BELOW 11000 FT-
EASTERN SAWATCH MOUNTAINS ABOVE 11000 FT-
WESTERN CHAFFEE COUNTY BETWEEN 9000 AND 11000 FT-
CENTRAL CHAFFEE COUNTY BELOW 9000 FT-
WESTERN MOSQUITO RANGE/EAST CHAFFEE COUNTY ABOVE 9000 FT-
SAGUACHE COUNTY WEST OF CONTINENTAL DIVIDE BELOW 10000 FT-
SAGUACHE COUNTY EAST OF CONTINENTAL DIVIDE BELOW 10000 FT-
LA GARITA MOUNTAINS ABOVE 10000 FT-
UPPER RIO GRANDE VALLEY/EASTERN SAN JUAN MOUNTAINS BELOW 10000 FT-
EASTERN SAN JUAN MOUNTAINS ABOVE 10000 FT-
DEL NORTE VICINITY/NORTHERN SAN LUIS VALLEY BELOW 8500 FT-
ALAMOSA VICINITY/CENTRAL SAN LUIS VALLEY BELOW 8500 FT-
SOUTHERN SAN LUIS VALLEY-
NORTHERN SANGRE DE CRISTO MOUNTAINS BETWEEN 8500 AND 11000 FT-
NORTHERN SANGRE DE CRISTO MOUNTAINS ABOVE 11000 FEET-
SOUTHERN SANGRE DE CRISTO MOUNTAINS BETWEEN 7500 AND 11000 FT-
SOUTHERN SANGRE DE CRISTO MOUNTAINS ABOVE 11000 FT-
NORTHWESTERN FREMONT COUNTY ABOVE 8500 FT-
WESTERN/CENTRAL FREMONT COUNTY BELOW 8500 FT-
WET MOUNTAIN VALLEY BELOW 8500 FEET-
WET MOUNTAINS BETWEEN 6300 AND 10000 FT-
WET MOUNTAINS ABOVE 10000 FT-
TELLER COUNTY/RAMPART RANGE ABOVE 7500 FT/PIKES PEAK BETWEEN
7500 AND 11000 FT-PIKES PEAK ABOVE 11000 FT-
CANON CITY VICINITY/EASTERN FREMONT COUNTY-
NORTHERN EL PASO COUNTY/MONUMENT RIDGE/RAMPART RANGE BELOW
7500 FT-
COLORADO SPRINGS VICINITY/SOUTHERN EL PASO COUNTY/RAMPART RANGE
BELOW 7400 FT-PUEBLO AND VICINITY/PUEBLO COUNTY BELOW 6300 FT-
WALSENBURG VICINITY/UPPER HUERFANO RIVER BASIN BELOW 7500 FT-
TRINIDAD VICINITY/WESTERN LAS ANIMAS COUNTY BELOW 7500 FT-
CROWLEY COUNTY-LA JUNTA VICINITY/OTERO COUNTY-
EASTERN LAS ANIMAS COUNTY-WESTERN KIOWA COUNTY-
EASTERN KIOWA COUNTY-LAS ANIMAS VICINITY/BENT COUNTY-
LAMAR VICINITY/PROWERS COUNTY-SPRINGFIELD VICINITY/BACA COUNTY-
1151 AM MDT TUE MAY 1 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL...EAST
CENTRAL...SOUTH CENTRAL AND SOUTHEAST COLORADO.

.DAY ONE...TODAY AND TONIGHT

ISOLATED TO SCATTERED AFTERNOON THUNDERSTORMS WILL DEVELOP ACROSS
SOUTH CENTRAL AND SOUTHEAST COLORADO TODAY.  THUNDERSTORMS COULD BECOME
STRONG...ESPECIALLY ALONG THE EASTERN SLOPES OF THE SOUTHEAST
MOUNTAINS AND ADJACENT PLAINS AFTER 2 PM...WHERE THUNDERSTORMS WILL
BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL...ALONG WITH WIND
GUSTS UP TO 35 MPH...SMALL HAIL UP TO 1/2 INCH IN DIAMETER...AND
DANGEROUS CLOUD TO GROUND LIGHTNING.  ACROSS THE WESTERN MOUNTAINS
AND HIGH VALLEYS...THE MAIN THREAT FROM THUNDERSTORMS WILL BE WIND
GUSTS UP TO 45 MPH...DANGEROUS CLOUD TO GROUND LIGHTNING...AND BRIEF
RAINFALL.

A WEATHER DISTURBANCE WILL MOVE ACROSS COLORADO TONIGHT...CAUSING
SHOWERS AND THUNDERSTORMS TO BECOME MORE NUMEROUS THIS EVENING...
WITH WIDESPREAD SHOWERS CONTINUING AFTER MIDNIGHT. LOCALLY HEAVY
RAINFALL WILL BE POSSIBLE WITH THE STRONGER STORMS...ESPECIALLY
ALONG THE EASTERN SLOPES OF THE SOUTHEAST MOUNTAINS. LOCAL AREAS
COULD EXPERIENCE PROBLEMS WITH INCREASED RUN OFF AND LOCALIZED
FLOODING UNDER THE HEAVIER AND PERSISTENT SHOWERS.

THERE WILL BE THE POTENTIAL FOR STEADY LIGHT TO MODERATE RAINFALL
ACROSS THE EASTERN SAN JUAN...LA GARITA...AND SOUTHERN SANGRE DE
CRISTO MOUNTAINS TONIGHT. SNOW PACK LEVEL IS AROUND 8000 FEET.
THIS COMBINED WITH FREEZING AND SNOWFALL LEVELS AROUND 10000 FEET
WILL SUPPORT RELATIVELY WARM RAINFALL IN MELTING SNOW PACK. IF
THIS OCCURS...IT WILL FILL UP STREAMS AND RIVERS IN THESE LOCATIONS.
THE RIO GRANDE ACROSS THE EASTERN SAN JUAN MOUNTAINS AND SAN LUIS
VALLEY COULD START TO RISE LATER TONIGHT INTO WEDNESDAY.

NUMEROUS RAIN AND SNOW SHOWERS WILL CONTINUE OVERNIGHT ACROSS THE
WESTERN MOUNTAINS.  SNOW LEVELS WILL DROP TO AROUND 10000 FEET AFTER
MIDNIGHT...WITH 2 TO 5 INCHES OF SNOWFALL POSSIBLE ACROSS THE HIGHER
ELEVATIONS BY EARLY WEDNESDAY MORNING.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED AFTERNOON AND EVENING THUNDERSTORMS WILL DEVELOP
WEDNESDAY OVER THE ENTIRE REGION...AND A FEW STORMS MAY PRODUCE
LOCALLY HEAVY RAIN...MAINLY OVER THE INTERSTATE 25 CORRIDOR AND
EASTERN MOUNTAINS.

ON THURSDAY...ISOLATED THUNDERSTORMS WILL DEVELOP OVER THE EASTERN
MOUNTAINS AND PLAINS...AND A FEW STORMS MAY BECOME STRONG DURING
THE AFTERNOON AND EVENING.

ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE EACH DAY FOR FRIDAY
THROUGH MONDAY. A STRONG UPPER LEVEL STORM MAY STALL OVER SOUTHERN
CALIFORNIA DURING THE WEEKEND...WHICH MAY RESULT IN SOME LOCALLY
HEAVY RAIN ON SUNDAY AND MONDAY.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS WILL NOT BE NEEDED TODAY OR TONIGHT.

METZE