Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 022320
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
620 PM CDT SAT MAY 2 2015

.SYNOPSIS...
ISSUED AT 236 PM CDT SAT MAY 2 2015

A WEAK UPPER LEVEL DISTURBANCE IS PRODUCING SCATTERED LIGHT RAIN
SHOWERS OVER SOUTH CENTRAL IOWA WHICH HAVE HELD TEMPS DOWN IN THE
50S IN SOME LOCATIONS. MID AND HIGH CLOUDS OVER EASTERN IOWA AND
NORTHWEST ILLINOIS HAVE TAKEN SOME EDGE OFF THE SUNSHINE...THOUGH
TEMPS OVER MOST OF THE AREA HAVE PUSHED WELL UP INTO THE 70S.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 236 PM CDT SAT MAY 2 2015

THE WEAK UPPER LEVEL SYSTEM WILL CONTINUE TO MAKE SLOW PROGRESS
EASTWARD THROUGH THE NIGHT WHILE LOSING DIURNAL SUPPORT AND MOVING
INTO DRIER AIR. THUS POPS AND QPF WILL BOTH BE LOW AS PRECIP
SHOULD BE IN THE FORM OF LIGHT SPRINKLES. CLOUD COVER WILL HOLD
TEMPS UP OVERNIGHT WITH LOWS IN THE 50S.

FOR TOMORROW...THIS SYSTEM WILL BE MOVING EAST WHILE A SECOND
SHORTWAVE TROUGH IS PROGGED TO BEGIN MOVING IN THE AREA LATER IN
THE AFTER IN THE NORTHWEST. SO FOR ALMOST ALL AREAS FOR MOST OF
THE DAY...DRY WEATHER WILL PREVAIL. WE SHOULD HAVE SUFFICIENT
SUNSHINE TO PUSH TEMPS A FEW DEGREES HIGHER THAN TODAY...AND WITH
GOOD MIXING SEE SOME GUSTY WINDS LEADING INTO THE RAIN EVENT
SUNDAY NIGHT.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 236 PM CDT SAT MAY 2 2015

OVERVIEW...THE POLAR UPPER JET WILL BE LOCATED ALONG THE
U.S./CANADIAN BORDER SUNDAY NIGHT AND WILL THEN SHIFT INTO NORTHERN
CANADA THROUGH THE WEEK. UPPER-LEVEL RIDGING BUILDING IN ACROSS THE
CENTRAL U.S. BEHIND THE POLAR JET WILL RESULT IN A SIGNIFICANT
CHANGE TO A MUCH MORE MOIST ATMOSPHERE. MEAN 850-300MB WINDS WILL
SLOWLY VEER FROM WESTERLY TO SOUTHWESTERLY DURING THE EARLY PORTION OF
THE WEEK. PWAT VALUES WILL BE ABOVE AVERAGE DURING THIS TIME.

SUNDAY NIGHT...A LOW PRESSURE SYSTEM OVER SOUTHERN ONTARIO WILL DRAG
A WEAKENING COLD FRONT INTO E IOWA/W ILLINOIS AND BRING A CHANCE FOR
SHOWERS AND THUNDERSTORMS.

RELATIVELY LOW INSTABILITY...MUCAPE OF 500-1000 J/KG...AND LOW 0-6
KM SHEAR SHOULD PRECLUDE ANY SEVERE STORMS.

THE NAM AND GFS BOTH BRING A CONVECTIVELY INDUCED VORT. MAX OUT OF
THE CENTRAL ROCKIES THIS EVENING AND THEN OVER E IOWA/W ILLINOIS SUN
NIGHT. BEST CHANCE FOR SHOWERS/STORMS WILL BE ALONG AND NORTH OF A
LINE FROM IOWA CITY TO FREEPORT WHERE POTENTIAL VORT MAX...ASSUMING
IT EXISTS AS THE MODELS ARE ADVERTISING...TRACKS ALONG THE QUASI-
STATIONARY SFC-850MB BOUNDARY. CHANCES FOR RAIN WILL DECREASE
PRECIPITOUSLY TO THE SOUTH OF THE AFOREMENTIONED LINE.

MONDAY...SFC QUASI-STATIONARY BOUNDARY WILL BE MOVING SOUTHWARD
THROUGH THE DAY AND IS EXPECTED TO FALL APART AS IT ENTERS THE
SOUTHERN FORECAST AREA DURING THE EVENING.

ANOTHER POTENTIAL CONVECTIVE INDUCED PV ANOMALY MAY ORIGINATE...THIS
TIME OVER THE SOUTHERN ROCKIES...AND PROPAGATE OVER THE DVN CWA
PROVIDING SOME LIFT AND A GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS
DURING THE AFTN AND EVENING. THE GREATEST SHOWER/STORM COVERAGE IS
PROBABLY GOING TO OCCUR DURING THE EVENING. MUCAPE AGAIN NEAR 1000
J/KG BUT COULD BE NEAR 1500 J/KG ACROSS THE FAR SOUTHERN CWA.

PWAT VALUES ARE GOING TO BE RELATIVELY HIGH BETWEEN 1.25-1.50 INCHES
BUT THE NAEFS ONLY PLACES THIS IN THE 85TH-90TH PERCENTILE OR NEAR
1.5 STANDARD DEVIATIONS ABOVE THE MEAN FOR THE BEGINNING OF MAY. DO
NOT EXPECT SIGNIFICANT ISSUES WITH FLOODING.

RAINFALL AMOUNTS...500MB WINDS WILL BE NEARLY PARALLEL TO THE SFC-
850MB BOUNDARY WHICH MEANS THE POTENTIAL FOR TRAINING OF
SHOWERS/STORMS IS THERE. MOST AREAS WILL LIKELY RECEIVE BETWEEN 0.25
TO 0.75 INCHES...BUT THERE COULD BE A ZONE OF HIGHER AMOUNTS.

TUESDAY AND WEDNESDAY...A WARM FRONT WILL LIFT INTO THE NORTHERN CWA
TUE AFTN WITH HIGHS NEAR NEAR 70 F ALONG THE FRONT AND IN THE LOWER
80S ACROSS THE SOUTHERN CWA. SCT SHOWERS/STORMS ARE POSSIBLE MAINLY
IN THE MORNING. WEDNESDAY WILL BE WARM AND MOSTLY DRY AS THE
SOUTHERLY FLOW INCREASES AND THE RIDGING CONTINUES TO BUILD.

THURSDAY AND FRIDAY....TEMPS WILL REMAIN IN THE UPPER 70S TO LOWER
80S.AN ORGANIZED UPPER-LEVEL WILL EJECT OUT OF THE CENTRAL ROCKIES
BUT REMAIN WELL TO THE WEST OF THE MIDDLE TO UPPER MISSISSIPPI
VALLEY REGION...OVER NEBRASKA AND THE DAKOTAS.

CHANCES FOR SCT SHOWER/STORMS WILL INCREASE ESPECIALLY DURING PEAK
HEATING TIME. DISTANCE FROM THE CENTER OF THE MID-LEVEL LOW WILL
KEEP SYNOPTIC/QG FORCING RELATIVELY WEAK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 616 PM CDT SAT MAY 2 2015

VFR CONDITIONS TO CONTINUE THE NEXT 24 HOURS. A SERIES OF WEAK UPPER
DISTURBANCES WILL CONTINUE TO PRODUCE MID/HI CLOUDS WITH ISOLATED SHOWERS
ALONG AND SOUTH OF HIGHWAY 34 CORRIDOR THIS EVENING. COVERAGE LIMITED
ENOUGH TO USE VICINITY WORDING AT THE BRL TERMINAL. PARTLY CLOUDY SKIES
OF MID/HI CLOUDS TO CONTINUE THROUGH SUNDAY. SOUTH WINDS OF 5 TO 10
KTS TONIGHT WILL INCREASE AGAIN TO 10 TO 20+ KTS ON SUNDAY.

&&

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

&&

$$

SYNOPSIS...WOLF
SHORT TERM...WOLF
LONG TERM...UTTECH
AVIATION...NICHOLS


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