000
FXUS63 KDVN 110918
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
318 AM CST THU MAR 11 2010


.SYNOPSIS...
A LARGE UPPER LOW WITH ADDITIONAL SHORT WAVE TROFS FEEDING INTO IT
IS CENTERED OVER KANSAS CITY THIS MORNING. A LARGE PINWHEEL OF
RAINFALL IS FOUND FROM THE LOWS CENTERS ACROSS IOWA...THEN EXTENDS
AS SHOWERS AND THUNDERSTORMS FROM EASTERN IOWA SOUTH TO ALABAMA. A
DRY SLOT IS OVER FAR SOUTHERN IOWA AND EXTENDS SOUTHWARD OVER
MISSOURI. THIS DRY SLOT IS QUICKLY MOVING NORTH AT THIS TIME...AND
SHOULD SPREAD OVER MUCH OF THE CWA BY 12Z.

&&

.SHORT TERM...TODAY AND TONIGHT...
RAINFALL TODAY IS NO CERTAIN AS WE HAVE THE DRY SLOT MOVING IN
AROUND 12Z IN THE NORTHWEST AND CENTRAL. THEREFORE THE WEST AND
SOUTH MAY BE RAIN FREE THIS MORNING AND POSSIBLY THIS
AFTERNOON...RESULTING IN A DRY AND BREEZY DAY. THE NORTH AND EAST
SHOULD NOT SEE THE DRY SLOT UNTIL AFTER 14Z...AND ARE GOING TO NEED
CATEGORICAL OR LIKELY POPS THIS MORNING. RAINFALL AMOUNTS SHOULD BE
LIGHT SINCE PCPN IS MOVING SO FAST...AND CONVECTION IS FOUND IN
SMALL CELLS WHICH DO NOT COVER MUCH TERRITORY UNDER THEM. IN OTHER
WORDS...ANY HEAVY RAIN WILL BE BRIEF.   MORE OF A CONCERN TODAY WILL
BE FOR SHALLOW MINI SUPERCELL THUNDERSTORMS DURING PEAK HEATING. THE
OCCLUDED FRONT SHOULD BE WORKING THROUGH THE CWA DURING THE 18Z TO
21Z PERIOD...AND PRIOR TO THIS...THE DRY SLOT SHOULD HAVE POTENTIAL
TO BRING ENOUGH SUN TO HEAT UP TEMPS INTO THE UPPER 50S TO LOWER 60S
ALONG AND EAST OF THE MISSISSIPPI RIVER. THE SHALLOW CAPE WILL HAVE
SUFFICIENT SHEAR TO PRODUCE ROTATING UPDRAFTS...AND POSSIBLE HAIL
AND ISOLATED TORNADOES. COVERAGE SHOULD BE LOW...AND CHANCE POPS AT
MOST SEEM WARRANTED. WILL COVER THIS THREAT IN THE HWO TODAY...BUT
IT SHOULD BE NOTED THAT THIS WILL BE A BRIEF WINDOW OF LOW COVERAGE
STORMS IF IT OCCURS.  OTHERWISE...TEMPS SHOULD BE SIMILAR TO
YESTERDAY TODAY...WITH MILD IN THE EAST AND SEASONALLY COOL IN THE
WEST.

TONIGHT...WINDS WILL GRADUALLY LIGHTEN UP...AND WITH THE COLD WET
GROUND...WE MAY YET AGAIN SEE FOG FORM. WE WILL INCLUDE A SMALL
CHANCE FOR AN ISOLATED SHOWER AS WELL WITH THE UPPER LOW SPINNING
VERY CLOSE BY.  LOWS TONIGHT LOOK TO FALL BACK INTO THE UPPER 30S.
..ERVIN..

.LONG TERM...FRIDAY THROUGH WEDNESDAY...
PRIMARY FOCUS IS RAIN CHANCES THROUGH THE WEEKEND AS AREA REMAINS
UNDER THE INFLUENCE OF THE LARGE UPPER LOW TO THE SOUTHEAST.

MOST SIGNIFICANT CHANGES THIS MORNING ARE TOWARD WETTER CONDITIONS
FRIDAY NIGHT INTO SAT. 00Z MODELS CONTINUE A TREND THAT APPEARED IN
THE PAST COUPLE RUNS. SHORTWAVE ENERGY FROM THE CURRENT
4 CORNERS UPPER WAVE IS SHOWN ROTATING AROUND BOTTOM OF THE UPPER
LOW...THEN LIFTING N AND THEN NW...RESULTING IN A DEVELOPING SURFACE
LOW THAT CHURNS N-NW FROM KY AND TN FRI...TOWARD CENTRAL IL ON
SATURDAY. THIS RESULTS IN A LARGE CHUNK OF WRAP AROUND AND
DEFORMATION ZONE RAIN DEVELOPING WESTWARD FROM NRN IL INTO EASTERN
IA FRIDAY NIGHT. 00Z ECMWF...GFS...NAM AND UKMET RUNS...WHILE
OFFERING SLIGHTLY DIFFERENT TRACKS AND INTENSITY OF THE SURFACE
LOW...ALL HAVE MORE SIMILAR UPPER LEVEL LOW PLACEMENT AND WIDESPREAD
LIGHT TO MODERATE QPF OVERSPREADING THE FORECAST AREA FRIDAY NIGHT
AND CONTINUING THROUGH SAT. 00Z GEM IS THE ODD MODEL OUT...WITH ITS
00Z RUN DEPARTING FROM PREVIOUS RUNS THAT WERE CLOSER TO CURRENT
MODEL CONSENSUS. WITH DIFFERENT HANDLING OF THE PHASING OF THE UPPER
LOWS...ITS MORE EASTERLY H5 LOW CENTER...AND SURFACE LOW WELL TO THE
SE OVER THE OHIO RIVER VALLEY WOULD KEEP MOST OF THE AREA DRY FRI
NIGHT INTO SAT.

FOLLOWING THE LATEST MODEL CONSENSUS...HAVE RAISED POPS CONSIDERABLY
FRI NIGHT INTO SAT. HAVE RAISED QPF AMOUNTS TO AROUND .2 TO .3 INCH
RANGE FRI NIGHT AND TO AROUND .1 TO .2 INCH RANGE FOR SAT...STAYING
CONSERVATIVE AND CLOSE TO HPC GUIDANCE WITH THIS INITIAL CHANGE.
HOWEVER...THIS WILL NEED TO BE WATCHED CAREFULLY GIVEN THE HYDRO
SITUATION. 00Z MODEL QPF SUGGESTS AMOUNTS AS HIGH AS .75 TO 1.25
OVERNIGHT FRI NIGHT...AND THEN .25 TO .5 RANGE FOR SAT.

CONTINUED DEEP CYCLONIC FLOW AND WRAP AROUND MOISTURE WILL KEEP AT
LEAST LOW CHANCE POPS FOR RAIN GOING THROUGH SUN. TEMPERATURES
SHOULD STAY NEAR PERSISTENCE...AND SEASONABLY MILD THROUGH THE
WEEKEND. MON INTO AT LEAST MON NIGHT STILL LOOK TO BE DRY WITH AT
LEAST A BRIEF PERIOD OF ANTICYCLONIC FLOW AT THE SURFACE AND ALOFT.
NO CHANGES MADE TO FORECAST BEYOND SUNDAY.
..SHEETS..

&&
.AVIATION...
A CHALLENGING FORECAST IS AGAIN IN STORE...AS AN UPPER LOW CREATES
PERIODS OF VFR AND LIFR CONDITIONS OVER THE TAF SITES. AFTER A
PERIOD OF MVFR CIGS AND VISIBILITY IN SHOWERS AND VERY ISOLATED
THUNDERSTORMS THIS MORNING...MLI AND BRL SHOULD BE VFR THROUGH THIS
EVENING. AN ISOLATED SHOWER OR STORM IS POSSIBLE DURING THE
AFTERNOON AT BRL AND MLI...BUT THE DOMINANT CONDITION WILL BE VFR.
FARTHER NORTH...AND CID AND DBQ...FREQUENT LIFR CIGS AND 1/4 MILE
VISIBILITY IS POSSIBLE THROUGH EARLY THIS MORNING...FOLLOWED BY
MAINLY MVFR CIGS AND GOOD VISIBILITY THROUGH THE EVENING. EAST TO
SOUTHEAST WINDS TODAY WILL BECOME LIGHT NORTHEAST TONIGHT. AFTER MID
EVENING...MORE FOG AND STRATUS IS LIKELY AT ALL SITES WITH LIFR
CONDITIONS. ..ERVIN..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.

&&

$$

ERVIN/SHEETS/ERVIN

NWS DVN Office Area Forecast Discussion