Lightning Strike in Iowa, March 6, 2010

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
1135 PM CST SAT MAR 6 2010

...UPDATED AVIATION DISCUSSION...

.SHORT TERM /TONIGHT/...
PRECIP ASSOCIATED WITH NE CLOSED LOW WILL BE PRIMARY CONCERN
TONIGHT.  ALTHOUGH NOTED AND COINCIDENT DPVA...THETA-E ADVECTION AND
FRONTOGENETICAL FORCING AXES APPEAR TO BE ALIGNED WITH CURRENT BAND
OF SHOWERS ACROSS MO/IA/MN...DEEP LAYER QG FORCING MAX IS STILL
UPSTREAM IMMEDIATELY AHEAD OF LOW CORE IN ERN NE.  IT IS NOT
PRODUCING MUCH PRECIP AT THE MOMENT HOWEVER...LIKELY DUE TO LIMITED
MOISTURE IN SW-NE DRY SLOT.  EVEN THOUGH RADAR MOSAIC SHOWS LITTLE
UPSTREAM OUTSIDE OF NEAR LOW CORE...NAM/GFS/ECMWF AND EVEN HIGHER
RESOLUTION DMX WRF/SPC WRF-NMM RUNS ALL BREAK OUT ADDITIONAL PRECIP
JUST AHEAD OF SYSTEM THIS EVENING AS IT REACHES IA.

AM SOMEWHAT SKEPTICAL THAT MODELS ARE OVERDOING PCPN IN THIS
SITUATION AS SOMETIMES OCCURS WITH MATURE CLOSED LOWS...BUT BOTH
NAM/GFS 290-300K LAYERS ROOTED AT BASE OF LOWER STATIC STABILITY
SEEM TO DEPICT REALITY FAIRLY WELL RIGHT NOW AND STILL EXPAND UVM IN
MOISTURE TRANSPORT ZONE LATER THIS EVENING SO HAVE CATEGORICAL POPS
IN MANY LOCATIONS.  ALTHOUGH IA NEVER REALLY GETS INTO WARM SECTOR
WITH SFC LOW PASSAGE JUST TO OUR SOUTH...TEMPS/DEWPOINTS SHOULD
REMAIN JUST WARM ENOUGH TO KEEP PRECIP ALL RAIN.  WEAK MUCAPE AXIS
ALSO GETS INTO SRN IA TOO SO WHILE LITTLE TO NO THUNDER HAS BEEN
OBSERVED RECENTLY HAVE KEEP ISOLD THUNDER WORDING GOING SOUTH.

MOST MODELS...ESPECIALLY HIGHER RESOLUTION NAM/WRF RUNS...ARE BEING
OVERLY INFLUENCED BY SNOWPACK AND NOT REFLECTING CURRENT OBS SO
STAYED WITH WARMER GFS MOS AND EVEN RAISED THAT A FEW DEGREES IN
SPOTS WITH NON-DIURNAL HOURLY TEMP TRACE.

.LONG TERM /SUNDAY THROUGH FRIDAY/...
ALL EYES IN THE LONG TERM FORECAST ARE ON THE STORM SYSTEM SET TO
BRING PRECIPITATION ACROSS THE AREA FOR SEVERAL DAYS NEXT WEEK. THIS
SYSTEM WILL BE COMING ASHORE NEAR THE CALIFORNIA/MEXICO BORDER ON
SUNDAY MORNING...THEN MOVING ACROSS THE SOUTHWESTERN U.S. BEFORE
CURVING NORTHEASTWARD OVER THE MIDWEST AND NEAR IOWA. THIS WILL
PLACE US UNDER DEEP RIDGING FOLLOWED BY SOUTHWESTERLY THEN SOUTHERLY
FLOW ALOFT AS THE SYSTEM APPROACHES. THERE IS UNANIMOUS AGREEMENT
AMONG THE PROGNOSTIC MODELS ON THIS GENERAL EVOLUTION...WHICH IS
CONSISTENT WITH CONCEPTUAL MODELS. HOWEVER...THE DEVIL AS ALWAYS
LIES IN THE DETAILS...AND THE SCENARIO IS COMPLICATED BY A LONGWAVE
TROUGH SET TO COME BARRELING ASHORE IN NORTHERN CALIFORNIA MONDAY
EVENING. AS THIS TROUGH DIGS INTO THE ROCKIES IT WILL LIKELY CLOSE
OFF A 500 MB LOW...AND THIS SYSTEM WILL INTERACT WITH THE FIRST
LARGE GYRE WHICH WILL BE SPINNING SOMEWHERE JUST TO OUR WEST OR
SOUTHWEST AT THE TIME. THE RESULT WILL BE A COALESCENCE OF THE
SYSTEM WHICH WILL CAUSE THE LARGE COMBINED STORM SYSTEM TO LINGER
OVER OUR AREA POTENTIALLY FOR SEVERAL DAYS...PROVIDING A PROLONGED
PERIOD OF PRECIP CHANCES.

WHILE THERE IS STILL UNCERTAINTY REGARDING THE TRACK AND TIMING OF
THE LARGE LOW DUE TO ITS INTERACTION WITH THE SECONDARY SYSTEM...IT
SEEMS CLEAR THAT THE WARM AIR/MOISTURE ADVECTION EARLY NEXT WEEK
FOLLOWED BY THE PERSISTENT CYCLONE OVERHEAD WILL RESULT IN PRECIP
ACROSS ALL OF THE AREA...WITH THE ONLY QUESTIONS THEN BEING
WHEN...HOW LONG...AND HOW MUCH. PRECIP WILL LIKELY BEGIN MONDAY
NIGHT IN THE SOUTHWEST...ALTHOUGH TIMING MAY BE DELAYED SOMEWHAT BY
SLIGHTLY DRIER LOW LEVEL AIR FILTERING IN FROM HIGH PRESSURE WELL TO
THE EAST. BY TUESDAY MORNING PRECIP SHOULD BE MOVING ACROSS MOST OR
ALL OF OUR COUNTIES...THEN LINGERING FOR SOME TIME. PRECIP CHANCES
ARE A GOOD BET AT LEAST THROUGH THURSDAY...AND THE ECMWF HOLDS US IN
IT THROUGH FRIDAY. IT REMAINS TO BE SEEN HOW MUCH PRECIP WILL BE
STRATIFORM VS CONVECTIVE...WITH CONVECTIVE ELEMENTS MOST LIKELY IN
THE SOUTH WHERE SOME MARGINAL INSTABILITY MAY BE PRESENT AT TIMES.
WITH THIS GENERAL THINKING IN MIND HAVE INCREASE POPS FOR SEVERAL
PERIODS FROM MONDAY NIGHT INTO THURSDAY...WITH CATEGORICAL POPS NOW
PRESENT ON MONDAY NIGHT AND TUESDAY. HESITATE TO PLACE THEM ANY
FURTHER OUT AS BY TUESDAY NIGHT THERE IS MORE UNCERTAINTY REGARDING
POTENTIAL CONVECTIVE ELEMENTS NEAR THE CENTER OF THE LOW...AS WELL
AS THE POSSIBLE PRESENCE AND LOCATION OF A DRY SLOT. IN TERMS OF
PRECIP TYPE WARM AIR WILL RESULT IN MOST OF THE PRECIP FALLING AS
RAIN...HOWEVER THERE COULD BE PERIODS OF LIGHT FREEZING PRECIP OR
SNOW IN THE NORTH/NORTHWEST DURING THE NIGHTTIME HOURS WHEN
TEMPERATURES MAY DIP BELOW FREEZING FOR A FEW HOURS. HAVE INCLUDED A
RAIN/SNOW MIX AT TIMES TO ACCOUNT FOR THIS. PRECIP AMOUNTS STILL TOO
EARLY TO DIAGNOSE...HOWEVER WITH SNOW MELTING RAPIDLY NEXT WEEK AS
TEMPERATURES STAY ABOVE FREEZING ACROSS MOST OF THE AREA THROUGH THE
NIGHT...IT WILL NOT TAKE A LOT OF RAIN ON TOP OF THE SNOW MELT TO
PRODUCE AT LEAST SOME FLOODING ACROSS THE AREA. ESF REMAINS IN
EFFECT FOR THE ENTIRE CWA AND THIS THREAT IS BEING MONITORED CLOSELY.

OTHERWISE...NOT MUCH ELSE TO SPEAK OF IN THE LONG TERM FORECAST. DID
NOT MAKE MUCH CHANGE TO TEMPS EXCEPT TO SHRINK THE DIURNAL RANGE
/I.E. RAISE THE MINS AND LOWER THE MAXES) AROUND TUESDAY/WEDNESDAY
DUE TO THICK CLOUD COVER AND LIKELIHOOD OF WARM AIR PUSHING IN FROM
THE SOUTH EVEN AT NIGHT...DEPENDING ON THE TRACK OF THE SURFACE LOW.

&&

.AVIATION...
07/06Z...CEILINGS AND VSBY VARYING FROM VFR TO MVFR...WITH LOCAL IFR
IN MODERATE SHOWERS CURRENTLY. MAIN BAND OF SHOWERS WILL CONTINUE TO
MOVE NORTHEAST OVER CENTRAL IOWA AND CLEAR OUT OF KFOD AND KDSM
SHORTLY AFT 06Z...BUT LINGER AT KMCW AND KALO TIL CLOSER TO 10Z.
HAVE NOT HAD ANY SIGNS OF THUNDER FOR A FEW HOURS NOW...SO HAVE
REMOVED ANY MENTION FROM TAFS. EXPECT MASS OF IFR CEILINGS TO PUSH
INTO CENTRAL IOWA A COUPLE OF HOURS AFTER THE RAIN ENDS. LOW LEVELS
REMAIN SATURATED THROUGH THE DAY AND INTO SUN NIGHT...SO ALTHOUGH
SOME RISE IN CEILINGS AND VSBY EXPECTED DUE TO HEATING OF THE
DAY...THEY SHOULD COME BACK DOWN AFTER SUNSET.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

SHORT TERM...SMALL
LONG TERM...LEE
AVIATION...MOYER

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
1136 PM CST SAT MAR 6 2010

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-080545-
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN-
WEBSTER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-GREENE-
BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS-POLK-JASPER-
POWESHIEK-CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION-
CLARKE-LUCAS-MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE-
DAVIS-
1136 PM CST SAT MAR 6 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE CHANCES OF ICE JAMS AND FLOODING WILL INCREASE NEXT WEEK.  THE
COMBINATION OF SNOWMELT ASSOCIATED WITH WARMING TEMPERATURES AND
ADDITIONAL RAINFALL TONIGHT AND NEXT WEEK MAY RESULT INITIALLY IN
ICE JAMS AND THEN EXPAND TO INCLUDE MORE GENERAL AND WIDESPREAD
RIVER FLOODING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED...HOWEVER ANY REPORTS OF
FLOODING AND ICE JAMS ARE ENCOURAGED.

SMALL/MOYER